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.
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