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The compendium consists of three major sections:

Water Supply Technologies

This section is a comprehensive compilation of relevant water supply technologies that can be implemented in a wide range of contexts from acute emergencies to long-term stabilisation and recovery settings. The technologies are categorised and ordered according to their functional group: Source, Intake, Abstraction, Treatment, Distribution/Transport, and Household Water Treatment and Safe Storage (HWTS).

Users have the choice between three distinct technology overview options:

Compact view (default setting): Simple table matrix of all emergency technologies only showing the name of the technology and sorted according to the functional groups they belong to.
Grid view: A more visual way of presenting all technologies by providing the technical drawings of all technologies in an overview grid.
List view: More detailed overview of all technologies displayed in a list that already provides details of selected technology parameters.

By clicking on a specific technology, the user can access a more in-depth technology information sheet with a description of the basic working principles and design considerations as well as key information regarding applicability, cost implications, space and materials needed, operation and maintenance (O & M) requirements, social and environmental aspects and links to further literature and resources.

Cross-Cutting Issues

This section presents cross-cutting issues and background information that should be considered when making technology and design decisions. It includes requirements for (1) an assessment of the initial situation including the existing institutional and regulatory environment and the rehabilitation and upgrade of existing infrastructure, (2) monitoring and quality control ranging from data flows and information/communication technology to working with sub-contractors, water quality monitoring and water safety and risk management, (3) conceptual aspects such as resilience and preparedness, the exit strategy and handover of infrastructure and specific features of urban settings and (4) design and social considerations such as inclusive and equitable design, hygiene promotion and market-based programming.

Glossary
This section provides concise definitions of all relevant technical terms used throughout the platform.

The eCompendium can be used in very different ways depending on who is using it and for what purpose.

Reference Tool: At its core the eCompendium is a user-friendly compilation of state-of-the-art information on all tried and tested emergency water supply technologies. Hence it can be used as a structured reference tool for WASH practitioners and capacity development institutions to easily find information on specific technologies, cross-cutting issues or key terms used. Basically, a more interactive version of the hard/softcopy publication. 

Filtering of Technologies and Rapid Decision Making: Using the filter bar at the top of the ‘water supply technology’ section can be another potential entry point that allows reducing complexity and pre-selecting only those technologies that are suitable for a specific scenario or context. Based on concrete site settings (like e.g. the phase of emergency for which a technology solution is needed, the application level or the local availability of materials) the number of potentially suitable technologies can be considerably reduced to a more digestible size and makes technology selection easier. The categorisation of technologies used for each of the filters should not be seen as fixed and incontrovertible and may vary under certain local conditions. The categorisation is rather meant to support rapid informed decision making and is a complement to, not a substitute for, sound professional judgement.

Watchlist: Specific technologies of interest can be put on a separate watchlist (by clicking on the asterisk next to each technology) either to safe it for later, for print out or to share and discuss it further with colleagues. The watchlist can be accessed by clicking on the ‘watchlist’ tab on the upper left corner. For each technology a 2-page pdf-document is available for download or print out.

The filter bar at the top of the ‘water supply technologies’ section allows reducing complexity and pre-selecting only those technologies that are suitable for a specific scenario or context. Based on concrete site settings the number of potentially suitable technologies can be considerably reduced to a more digestible size and makes technology selection easier. By clicking on the respective boxes under each of the filters only those technologies will be shown that correspond to the respective boxes. The currently active filters are always shown directly under the filter bar. The active filters can be cleared/deactivated by clicking on the ‘reset filter’ button or by deactivating individual boxes of currently active filters. The categorisation of technologies used in each of the filters should not be seen as fixed and incontrovertible and may vary under certain local site conditions. The categorisation is rather meant to support rapid informed decision making and is a complement to, not a substitute for, sound professional judgement. The available filter options include the following:
 
Response Phase

Indication on appropriateness of water supply technologies according to the three different emergency phases:

• Acute Response: immediately following an emergency
• Stabilisation: transition phase starting after the first weeks of an emergency lasting several months or longer
• Recovery: longer-term approach usually starting after immediate relief interventions aiming to recreate or improve on pre-emergency situation

The allocation of technologies to different emergency phases is mainly based on applicability, speed of implementation and material requirements. It allows giving a first general orientation but may differ in a specific local situation.

Application Level
Indication on the different spatial levels and scale for which the technology is most appropriate. It is subdivided into the following levels:

• Household: one unit serving one up to several individual households
• Neighbourhood: one unit serving a few to several hundred households
• City: one unit serving an entire settlement, camp or district

It allows giving a first general orientation but may differ in a specific local situation.

Management Level
Indication where the main responsibility for operation and maintenance (O&M) for a specific technology lies:

• Household: O&M tasks can be managed by the individual household
• Shared: group of users are responsible for O&M by ensuring that a person or a committee is in charge on behalf of all users
• Public: government, institutional or privately run facilities: all O&M tasks are assumed by the entity operating the facility

It allows giving a first general orientation but may differ in a specific local situation.

Local Availability (of Technology and Components)

Indication to what extent a technology and its components/materials are likely to be accessed locally and whether they need to be brought in from outside.

• Low local availability means that most or all technology components must be sourced from outside and are likely not to be available in-country
• Medium local availability means that some materials or components can be obtained easily, though some components maybe more challenging
• High local availability means that the technology or its components can be easily obtained in-country

Technical Complexity
Indication of the technical complexity of each technology, meaning the level of technical expertise needed to implement, operate and maintain the given technology. This can help planning in cases where skills and capacities are limited or temporarily unavailable.

• Low technical complexity means that only minimal technical skills and simple tools are required to implement, operate and maintain or repair a technology, which can be done by non-professionals and artisans
• Medium technical complexity means that certain skills and tools are required for either implementation, O & M or repair. Here, skilled artisans or engineers are required for the design and O & M.
• High technical complexity means that an experienced expert, such as a trained engineer, is required to implement, operate and maintain the technology in a sustainable manner

The categorisation is based on a comparative approach between the different technologies and is not to be considered in absolute terms.
 

Maturity Level
Indication whether or not a technology has been proven and tested in different response phases and if the technology has been established for a sufficient time for the required experience in set up, use and O & M.

• High level of maturity
• Medium level of maturity
• Low level of maturity

Selecting the most appropriate water supply technology(ies) for a specific context is a complex task requiring technical and analytical skills. The selection must be based on an assessment that includes a wide range of data gathered from field-level surveys (see X.1–X.4). The key decision criteria aim to give general guidance in the technology selection process and in the overall design of a water supply system. The same set of decision criteria are featured in each of the technology information
sheets.
 
1.   Response Phase
Indicates for which phase of the response the technologies are appropriate (provided they are to be newly built). Their suitability is characterised for the three response phases: Acute Response, Stabilisation and Recovery. An indication of whether a technology is suitable for a specific response phase is given using asterisks (two asterisks: suitable, one asterisk: less suitable, no asterisk: unsuitable). The level of appropriateness is decided on a comparative basis between the different technologies, mainly based on applicability, speed of implementation and material requirements. It is up to the compendium user to decide on the response phase for their specific situation.
 
2.   Application Level
The application level describes the different spatial levels and scale for which the technology is most appropriate. It is subdivided into the following levels:
Household (one unit serving one up to several individual households),
Neighbourhood (one unit serving a few to several hundred households),
City (one unit serving an entire settlement, camp or district)
An indication of whether a technology is suitable at a specific spatial level is given using asterisks (two asterisks: suitable, one asterisk: less suitable, no asterisk: unsuitable). It is up to the compendium user to decide on the appropriate level for their specific situation.
 
3.   Management Level
The management level describes where the main responsibility for operation and maintenance (O & M) for a specific technology lies:
Household: all O & M related tasks can be managed by the individual household
Shared: group of users places a person or a committee in charge of O & M on behalf of all users
Public: government, institutional or privately-run facilities where all O & M is assumed by the entity operating the facility
An indication regarding the appropriateness of each management level is given using asterisks (two asterisks: well-handled at that level, one asterisk: less suitable, no asterisk: unsuitable).
 
4.   Objectives/Key Features
This section gives a concise indication of the main features and functions of the specific technologies. It also provides general guidance for the immediate evaluation and classification of technologies and their suitability for an envisioned application or context.
 
5.   Local Availability of Technology and Components
This section indicates to what extent the technology and its components/materials are likely to be accessed locally and whether they need to be brought in from outside. Asterisks are used to indicate the local availability for the given technology (three asterisks: high availability, two asterisks: medium availability, and one asterisk: low or no availability). High local availability means that the technology or its components can be easily obtained in-country. Medium local availability means that some materials or components can be obtained easily, though some components maybe more challenging. Low local availability means that most or all technology components must be sourced from outside and are likely not to be available in-country.
 
6.     Technical Complexity
This section provides an overview of the technical complexity of each technology, meaning the level of technical expertise needed to implement, operate and maintain the given technology. This can help planning in cases where skills and capacities are limited or temporarily unavailable. Asterisks are used to indicate the technical complexity for the given technology (three asterisks: high complexity, two asterisks: medium complexity, and one asterisk: low complexity). Low technical complexity means that only minimal technical skills and simple tools are required to implement, operate and maintain or repair a technology, which can be done by non-professionals and artisans. Medium technical complexity means that certain skills and tools are required for either implementation, O & M or repair. Here, skilled artisans or engineers are required for the design and O & M. High technical complexity means that an experienced expert, such as a trained engineer, is required to implement, operate and maintain the technology in a sustainable manner. The categorisation is based on a comparative approach between the different technologies and is not to be considered in absolute terms.
 
7.   Maturity Level
This section gives an overview of the maturity level of each technology, indicating whether or not the technology has been proven and tested in different response phases and if the technology has been established for a sufficient time for the required experience in set up, use and O & M to exist. Asterisks are used to indicate the maturity level for the given technology (three asterisks: high maturity, two asterisks: medium maturity, and one asterisk: low maturity).
 
8.   Design Considerations
In this section, general and key design considerations are described, including general size and space requirements. This section does not describe the detailed design parameters for complete construction of a technology, but instead provides an idea of the features to consider as well as the main potential pitfalls to be aware of when designing the technology. This section helps the compendium user understand the technical design and complexity of a given technology.
 
9.   Materials
This section lists the different materials and equipment required for the construction, operation and maintenance of a given technology. It indicates whether materials are likely to be locally available or producible (e.g. wood and bricks) or whether materials will need to be imported or require special manufacturing, which will considerably delay implementation during an emergency. The materials section also indicates whether a technology can be prefabricated as a unit to speed up implementation.
 
10. Applicability
Applicability describes the contexts in which a technology is most appropriate. This section indicates the applicability of a technology in terms of type of setting, distinguishing between rural or urban and short-term or long-term settlements. It describes the response phases in which a technology can be implemented and the potential for replicability, scalability and speed of implementation. Other physical considerations of applicability are listed here, including required soil conditions, necessary water availability and groundwater table considerations (including aquifer types and properties). This section also provides information on the robustness (ability to withstand future disasters) of the technology and its susceptibility to climate change as well as the potential for the rehabilitation and/or expansion of already existing facilities.
 
11. Operation and Maintenance (O & M)
Every technology requires O & M, more so if it is used over a prolonged period of time. Therefore, the O & M implications of each technology must be considered during initial planning, especially because many technologies fail due to the lack of appropriate O & M. In this section, the main operation tasks that need to be considered and the maintenance that is required to guarantee long-term operation are listed. This section differentiates between different O & M skills and provides an indication of the frequency of O & M tasks and the time required to operate and maintain a technology. A list of potential misuses and pitfalls to be aware of is also provided.
 
12. Health and Safety
Most water supply technologies have health and safety implications. The health implications or risks described in this section should be considered during planning to reduce health risks in the local community and among personnel and staff. This section also describes overall risk management procedures, which could exclude a technology from potential use if safety cannot be guaranteed. Where relevant, the personal protective equipment needed to guarantee personal safety is listed. This section also provides information on the potential of a technology to reduce the pathogen load in the water (log removal values).
 
13. Costs
Each technology has costs associated with the construction, O & M and management, including resulting cost implications for other technologies along the water supply chain. Because costs are geographically dependent and cannot be described in absolute numbers, this section presents the main cost elements associated with a technology and a price range where possible, allowing for an initial approximation. While money is often available at the start of an emergency for capital expenditures (CAPEX), this availability usually decreases radically over time. Therefore, the selection of technologies needs to consider how to achieve the lowest possible operational expenditures (OPEX) for long-term solutions (>6 months) and/or establish services that will continue after the acute response phase, such as through the introduction of cost-recovery measures or strengthening of local management capacity.
 
14.   Social and Environmental Considerations
Social considerations are important when deciding on specific water supply technologies, especially at the user level. There are potential cultural taboos, user preferences and habits as well as local capacities that may be challenging, impossible or inappropriate to change. A water supply technology (as well as the water it provides) needs to be accepted/acceptable by the users as well as the personnel operating and maintaining it. Environmental considerations include the impact of the proposed technology choice on the local environment, the broader carbon footprint and its potential to exacerbate or mitigate the impact of climate change.
 
15. Strengths and Weaknesses
This section concisely summarises main strengths and weaknesses and thereby supports the decision-making process. The weaknesses of a technology might indicate that an existing exclusion criterion renders a technology unsuitable for a specific context. Both strengths and weaknesses can effectively inform decisions of users and all involved in the planning and implementation of the water supply system.
 
16. References and Further Readings
This section refers users to relevant publications and further reading materials related to a specific technology including a short description for each listed publication. Users can use the publication list to find additional relevant information (e.g. design guidelines, research papers, case studies) on specific technologies.

Drinking water supply systems can be graphically presented as a sequence of functional groups that can be linked together in various combinations. All components of the system, from the source to consumption, form a part of this sequence and are considered and displayed. The functional groups cluster the technologies that have similar functions. The eCompendium proposes six different functional groups from which technologies can be chosen to build a water supply system or service (of which some may already be in place in a specific context that can potentially be rehabilitated). Each functional group is identified by a distinctive colour; technologies within a given functional group share the same colour code for easy identification. Also, each technology within a functional group is assigned a reference code with a single letter and number.
 
Source (S): refers to the original raw water source and considers whether it provides enough water as well as the energy sources needed to power abstraction, treatment and transportation of the water. Typically, groundwater or surface water resources are exploited, though in areas with sufficient rainfall, rainwater may also be an appropriate complimentary water source. The quantity, quality and location of the source determine the subsequent water treatment and water supply system design. A variety of energy sources is available ranging from gravity (if the water source is elevated) and human power (for abstraction of comparably small water volumes) to traditional (e.g. electricity or diesel) or renewable (e.g. wind and solar) energy sources.
 
Intake (I) refers to the withdrawal system that collects water from the source. For each water source, there may be one or more intake systems available. Some intake systems may act as a reservoir for storing water or provide a certain degree of treatment. Intakes can be classified according to the water source: rainwater, surface water or groundwater intakes. The choice of intake systems depends on a number of factors, including the volume of water needed for the target population, availability of appropriate surfaces, characteristics of the water body, flow and flow characteristics, hydrogeological conditions, water accessibility, availability and the risk of contamination. Properly constructed intake systems should provide convenient and efficient access to water sources as well as protect those sources from contamination and prevent harm to ecosystems.
 
Abstraction (A) refers to the various ways of extracting/abstracting water through a pump. Pumps can be divided into three broad categories, depending on how water moves through the pump: (1) impulse pumps, (2) positive displacement pumps or (3) velocity pumps. A wide variety of pump types are commercially available, each with specific operational advantages. Choosing the most appropriate water abstraction technology depends on a range factors, such as the water source, intake structure, available energy source, elevation, required capacity, O & M requirements, local availability of components and service, socio-cultural and environmental considerations and other infrastructure already in place.
 
Treatment (T) refers to technologies for water treatment, which are generally appropriate for a larger group of users, such as communities, semi-centralised applications in neighbourhoods, and more centralised applications in urban areas. Water treatment technologies can be divided into three groups: (1) pre-treatment with the main objective of reducing raw water turbidity, (2) targeting primarily microbial contaminants and (3) targeting chemical contaminants of various origins, including high salinity. Some technologies can function as a single-step treatment, while others may need to be applied as part of a multi-stage treatment system.
 
Distribution/Transport (D) refers to technologies for delivering water from the source, pumping station or water treatment plant to the user. These are either communal distribution systems with varying complexity, scale and types of connections or privately adopted solutions. Distribution/Transport also includes water storage technologies that can play a significant role within the distribution system as well as at the Intake (I) and during Treatment (T).
 
Household Water Treatment and Safe Storage (H) refers to household water treatment and safe storage technologies used as single-stage water treatment alternatives when centralised or community scale treatment is not available or the quality of produced water does not meet the applicable standards. Should contamination occur during transport between the point of abstraction/collection and the point of use, household water treatment is a viable option to remedy this and includes the safe storage of water within the household.

Drinking water supply systems can be graphically presented as a sequence of functional groups that can be linked together in various combinations. All components of the system, from the source to consumption, form a part of this sequence and are considered and displayed. The six functional groups are represented by colour-coded columns as follows: Source, Intake, Abstraction, Treatment, Distribution/Transport, Household Water Treatment and Safe Storage.
 
Before exploitation can begin, the water source must be identified. In the acute phase of an emergency, the chosen water source may not be ideal (such as in terms of water quality) but may still be chosen due to other advantages (such as proximity and/or accessibility). As the emergency stabilises, more time may become available for developing sustainable alternative sources (e.g. a Groundwater source [S.5] requiring less ongoing treatment or a Spring [S.6] amenable to gravity flow rather than pumping).
 
The intake chosen depends, for example, on the time available to build it, and thus in the acute response phase, the choice of intake is often limited to those that can be developed quickly, such as a River or Lake Intake [I.3], or where existing Wells [I.7] or Boreholes [I.8] can be commandeered. Again, as the emergency progresses, additional time availability may allow the construction of other intakes more suited to the ongoing situation.
 
The water will need to be abstracted from the intake via an energy source. During the acute phase of a response, this often means some kind of pump (see [A.1]–[A.9]) that is powered by Electricity [S.11] or Diesel [S.12], although these may be replaced with more sustainable alternatives over time, such as Gravity [S.7] or Solar Energy [S.10].
 
Following abstraction, the water will usually need treatment prior to distribution. The level and complexity of the required treatment largely depends on the water quality and the standards and indicators to be reached, though this is also dependent on the stage of the emergency response. For example, in the acute phase, the priority is always to reduce microbiological contamination immediately, as this has the highest short-term health impact. Over time, other treatment methods can be added to address additional sources of contamination that have long-term health impacts (e.g. fluoride). In the acute response, prefabricated, packaged water treatment plants are very useful, as they are designed to treat turbid or contaminated surface water in large volumes. They also tend to use treatment methods such as (Assisted) Sedimentation with or without Filtration ([T.4], [T.5]) that are effective reducing significant amounts of chemicals that may have long-term health impacts. Over time, more sustainable treatment options that take longer to set up can be designed. For example, Slow Sand Filters [T.9] dramatically reduce the chemical requirements in water treatment, thus reducing running costs.
 
Subsequently, treated water will need to be both transported from the source to the vicinity of the users (such as using trucks or pipes to transport water to storage tanks) and from the storage tanks to the users (such as using pipes and jerrycans). In the acute response, it is common to rely more on short-term solutions such as Water Trucking [D.3] to transport water to Flexible Bladder [D.5], which in turn are connected to Tap Stands (see [D.]). However, solutions like water trucking are very expensive and bladder tanks are not robust in the longer term. Hence other transport/distribution systems that are less expensive, more sustainable, and more convenient should be deployed as soon as possible. These include pipelines using gravity or solar pumping, tanks with larger volumes made from more robust materials (see [D.6]) and distribution systems that bring water closer to, or even into, the household (see [D.7], [D.8]).
 
Drinking water must be stored safely in the household, and users can perform additional treatments within the household if necessary. Historically, certain household-level water technologies have been useful in the acute response before centralised treatment is set up or where it is not possible, e.g. the use of Coagulant-Flocculant Sachets [H.8]. In some acute situations where the population is already familiar with a particular household water treatment product, these can be included as part of the first non-food item distributions in the acute phase to help address water quality, especially in dispersed populations. Overall, many of these household-level water treatment systems are also good long-term solutions where centralised water treatment is not reliable and where pilot interventions can be done prior to scaling up, potentially using local markets to do so.
 
Some humanitarian WASH organisations also use package systems consisting of several technologies from the functional groups presented above that are usually flown in, are immediately deployable and allow for a safe provision of water from the source to the user in a variety of contexts. These systems are usually only used in the acute response before context-specific, long-term solutions can be identified and set up or existing systems can be rehabilitated.
 
It is important to note that it is not always necessary for water to pass through all functional groups to reach a consumer. In some systems, treatment is excluded due to the high quality of the source water. Water can also be supplied by gravity to avoid the need for pumping.
 
There are multiple factors that influence an initial decision about which technologies to choose in an emergency. In reality, some experience is required to choose the most suitable technologies for the respective response phase, and it is not possible to be too prescriptive about this. The following steps provide some guidance to determine appropriate water supply technology options for specific contexts:
 

• Assessment of the initial situation (see [X.1] – [X.4]), including the identification and accessibility of available water sources with sufficient yields, the practices, preferences and water demand of the user groups to be served, the geographical conditions, the existing infrastructure and services in the area and the institutional and regulatory environment.
• Identification of technologies that may be appropriate for each of the functional groups based on the technology overview and the more detailed descriptions from the Technology Information Sheets. In the Treatment (T) functional group, multiple technologies may be applicable depending on potential contamination of the available water resource(s). Parts of a water supply system may already exist that can be integrated.
• Combine technologies logically to build several appropriate water supply systems.
• Compare the systems and iteratively change individual technologies based on considerations such as user/community priorities, time pressure

Common categories used to distinguish between the different response phases are: (1) acute response, (2) stabilisation and (3) recovery. The identification of these broad phases is helpful when planning assistance, though the division should be viewed as theoretical and simplified, as it is modelled after singular disaster events.
 
Acute Response: This refers to humanitarian relief interventions that are implemented immediately following natural disasters, conflicts, epidemics/pandemics, or a further degradation of a protracted crisis situation. It usually covers the first hours and days up to the first few weeks or months, where effective short-term measures are applied to quickly alleviate the emergency situation until more permanent or durable solutions can be found. An initial (rapid) assessment (see [X.1] – [X.4]) is needed to identify priority needs and to get a better understanding of the contextual and technical aspects as well as the institutional and actor landscape. The purpose of interventions in the acute response phase is to secure and ensure the survival of the affected population, guided by the principles of humanity, neutrality, impartiality and independence. It must also be considered that in certain emergencies, the affected people are often much more vulnerable to disease due to non-existing or inadequate WASH facilities and an inability to maintain good hygiene. Therefore, essential water-supply related services needed at this stage include the provision of sufficient supplies of clean water for drinking, personal hygiene and cooking, primarily on a communal level, and ensuring a safe environment while preventing contamination of water sources. Where applicable, the preferred intervention is the quick rehabilitation or reinforcement of existing water supply infrastructure (alongside short-term rapid emergency water supplies, if needed) and the provision of tools and equipment to ensure basic O & M services. To ensure that the entire affected population has safe and adequate access to water supply services and that services are appropriate, relevant water authorities and local first responders need to be involved from the onset, and it must be ensured that there is an equitable participation of men, women, children and marginalised and vulnerable groups in planning, decision-making and local management (see [X.15], [X.16]). Intervention at this stage in an emergency is largely provided by local resources, as it takes time for external support agencies to mobilise. However, local resources are often unprepared for such events, meaning those affected have to largely deal with the emergency themselves.
 
Stabilisation: The stabilisation or transition phase usually starts after the first weeks/months of an emergency and can last to around half a year or longer. The main focus, apart from increasing service coverage, is the incremental upgrade and improvement of temporary emergency structures that would have been installed during the acute phase or the replacement of temporary technologies with more robust long-term solutions. This phase includes the establishment of community-supported structures with a strong focus on the entire WASH system, the gradual involvement of water utility structures where applicable, and the consideration of water safety and risk management measures (see [X.7], [X.8]). In this phase, water and energy sources should be reconsidered after accounting for environmental factors and long-term sustainability, particularly where groundwater is used as the major water source or where the water supply relies on water trucking. Water supply hardware solutions should be based on appropriate technologies and designs, ideally using locally available materials. A detailed assessment is required to respond adequately within a given local context and to increase the long-term acceptance of the planned interventions (see [X.1] – [X.4]). Emphasis should be given to aspects such as taste, odour and colour of the supplied water, as these will affect acceptance, as well as to hygiene-related issues that imply certain levels of behaviour change (see [X.16]). The scope of using market-based approaches (see [X.17]) should also be examined. As in the acute phase, the equitable participation of men, women, children and marginalised and vulnerable groups in planning, decision-making and local management is key to ensuring the entire affected population has safe and adequate access to water supply services and that services are appropriate. During the stabilisation phase, relevant resilience and disaster risk reduction measures should be pre-emptively considered, particularly if another disaster is likely to happen (see [X.10]).
 
Recovery: The recovery phase, sometimes referred to as the rehabilitation phase, aims to recreate or improve on the pre-emergency situation of the affected population by gradually incorporating development principles. This phase usually starts after or even during relief interventions (usually >6 months) and can be seen as a continuation of already executed relief efforts. Overall, it can prepare the ground for subsequent development interventions and gradual handing over to medium- to long-term partners. Depending on local needs, the general timeframe for recovery and rehabilitation interventions is usually between six months to three years, though difficult situations may need up to five years or more, such as in conflict-affected areas. Recovery and rehabilitation interventions are characterised by the active participation of local partners and authorities in the planning and decision making to build local capacities and contribute to the sustainability of the interventions. The scope of using market-based approaches (see. [X.17]) or introducing tariff systems for water use in the long-term should be further examined here. Water supply recovery interventions can take diverse forms and depend on local conditions as well as the actual needs of the affected population. Beyond the technical implementation of a water supply system, these interventions include significant efforts to strengthen WASH service structures and systems and promote markets for water services. In long-lasting camp situations that may develop into permanent settlements, interventions might include upgrading the existing emergency water supply infrastructure. Recovery interventions also include long-term capacity development and training, including working with relevant local authorities and development partners. Stronger collaboration with local governments, utilities, civil society, private sector and the handing over of responsibilities are also paramount. This necessitates the increased participation of involved stakeholders in planning and decision-making early on. Where possible, recovery interventions should consider that the investments made may provide a foundation for further expansion of WASH facilities and services. In addition, recovery interventions may include relevant resilience and disaster risk reduction measures (see [X.10]). Recovery interventions should include a clear transition or exit strategy (see [X.11]), including hand-over to local governments, communities or service providers to ensure that the service levels created can be maintained.

Emergencies can arise from a range of scenarios and can be either acute and time-limited or chronic and protracted in nature. The scenarios leading to emergencies can be broadly categorised as follows:

Emergencies Triggered by Natural or Technological Hazards: Earthquakes, volcanic eruptions, landslides, floods, storms, droughts, temperature extremes and disease epidemics/ pandemics (e.g. Cholera, Ebola or Covid-19) are natural hazards that can cause humanitarian disasters claiming many lives and causing economic losses and environmental and infrastructure damage. However, humanitarian disasters only occur if a hazard strikes where populations are vulnerable to the specific hazard. The growing world population, continuing global urbanisation and changes in land use can further increase vulnerability to natural and technological hazards, such as dam failures and chemical or nuclear accidents. Such emergencies often result in a deterioration of environmental health conditions, particularly regarding access to basic WASH services. Infrastructure such as schools, roads, hospitals and water and sanitation facilities are often directly affected, reducing access to clean water, sanitation and relevant hygiene practices like handwashing, which increases the risk of water- and sanitation-related diseases.

Conflicts: This refers to societally caused emergency situations such as political conflicts, armed confrontations, and civil wars. Many displaced people (internally displaced and/or refugees) have to be housed in camps, temporary shelters, or host communities, where access to clean water, sanitation, and hygiene items needs to be guaranteed at very short notice and often must be maintained over long periods. Most displaced persons are usually absorbed by host communities. This can overburden the existing water supply (and sanitation) infrastructure, making it difficult to identify and quantify actual needs and potentially requiring upgrades to existing infrastructure. Due to conflict dynamics and because population displacement can occur (and dynamically change) over a longer period of time, it is often difficult to plan how long shelters and corresponding water supply infrastructure must remain in place. This required operational time can vary from a few weeks or months to several years or even decades. The majority of refugee camps are becoming increasingly longer term (10 years or more) that often develop into continuous urban settlements. Hence, all technologies implemented in such settings should be viewed through the lens of long-term sustainability. An adequate water supply source is generally the main criteria for siting a camp or displaced population. However, refugee camps are often constructed in water scarce environments, so it is important to make the decision to move people to water or bring water to people early on in the response. In many situations, settlement solutions are considered a short -term intervention, as it is politically undesirable to consider more permanent settlement options. Local authorities might oppose activities that are seen to make the water or sanitation infrastructure in a temporary settlement more permanent or better developed for fear of having long-term responsibility for the displaced population. This is further complicated if the conditions in the camp might become better than those in local settlements, which can create tension between the local and refugee populations. Such cases should be seen as opportunities to improve water supply services for both host and refugee communities.

Fragile States and Protracted Crises: Fragile states and countries in protracted crises are becoming increasingly more common. States can be considered fragile when they are unwilling or unable to meet their basic functions. For the affected population, safety may be at risk if basic social services are not provided or are only poorly functioning. Weak government structures or lack of government responsibility for ensuring basic services can increase poverty, inequality and social distrust and can potentially develop into a humanitarian emergency. Protracted crisis situations are characterised by recurrent disasters and/or conflicts, prolonged food crises, deterioration of the health status of people, breakdown of livelihoods and insufficient institutional capacity to react to crises. In these environments, a significant proportion of the population is acutely vulnerable to premature death or illness. The provision of basic water supply services is often neglected, and external support using conventional government channels can lead to highly unsatisfactory experiences. Under these conditions, it may be necessary to explore complementary and alternative means of service provision, basing it mainly on non- and sub-state actors at a relatively decentralised level. Water supply technologies should be selected that can withstand theft (as far as possible) and have the fewest external inputs as possible (e.g. fuel or chemicals).

(High-) Risk Countries Continuously Affected by Disasters and Climate Change: Climate change and the increased likelihood of associated natural hazards is an enormous challenge for many countries. The risk that natural events become a disaster is largely determined by the vulnerability of the society, the susceptibility of its ecological or socio-economic systems and the impact of climate change both on occasional extreme events (e.g. heavy rains causing floods or landslides) and on gradual climatic changes (e.g. temporal shift of the rainy seasons). Climate change also exacerbates problematic situations in countries that are already suffering from disasters. In addition to the immediate emergency response that may be required, it also needs a stronger focus from development actors to consider adequate preventative and disaster risk reduction (see X.10) measures. Existing water supply infrastructure may need adaptations or more appropriate and robust water supply systems may need to be introduced to increase resilience and help communities cope with climate-induced recurrent extreme weather events (e.g. raised water points for flood-prone areas or bigger storage tanks to withstand longer dry seasons). It may also include preparedness measures such as capacity development, equipment stockpiling and surge roster development. In addition, water supply systems may need to be prepared to serve climate change refugees.

Disasters can often be a mix of several categories (e.g. fragile or conflict-affected states hit by a natural disaster), which makes response targeting more difficult (e.g. targeting only those affected by the natural disaster vs. those affected by more chronic conditions). In addition, disaster and crisis scenarios can be further differentiated into sudden onset disasters (e.g. earthquakes or conflicts) and slow-onset disasters (e.g. droughts that may lead to a prolonged food crisis or fragile contexts that lead to the deterioration of services over time). Depending on the type of crisis, population and infrastructure may also be affected very differently. While some disasters may lead to massive population movements with implications for strong public health measures, others may only affect the infrastructure, which would shift the response focus to repairs and respective improvements.