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Which criteria should I consider to select a water source during an emergency?

#HowTos

This is a question that I've been asked in the field so I wanted to share it with everyone on KnowledgePoint

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Before selecting any water sources, consider the following points:

  • Acceptable yield?

o Demand vs yield

o Seasonal yield

o Future yield

  • Ease / ability to obtain an acceptable quality

  • Proximity to population

  • Time of set up vs urgency

o Technical

o Resource / logistical

  • Impacts of development on:

o Existing users

o Aquifers

o Environment

  • Costs:

o Capital

o Operation and maintenance

o Who pays?

  • Ease of O&M:

o Requirements

o Resource / logistical

o Availability of trained staff

  • Security, socio-political & cultural constraints:

o Security

o Cultural & socio-political issues

o Needs of host vs refugee population

o User preferences

  • Management & legal constraints?

o Management

o Land ownership

Technical options for water sources

For smaller population:

Groundwater and springs are best because:

  • No or little treatment needed (low turbidity = only chlorination)

  • No pumping needed

For larger populations in emergencies:

Disinfection is vital and quantity needs to be reliable.

Often surface water is a better early source until a more sustainable solution is exploited. For all sources seasonality is important.

Surface water:

  • Sometimes there is no choice

  • Quick and easily recharged source

  • Borehole water unacceptable to users (e.g. too saline)

  • Obvious solution

Be careful with:

  • If a body of open water is the only source of water it is likely to be used for many purposes by the community

  • Improvement of source & treatment therefore necessary

  • Sanitary surveys for risk assessment

Some basic things can be done prior to treatment to improve the source:

o Fence off the catchment, or at least prevent certain activities

o Keep people & animals out: bank-mounted devices

o Water is cleaner away from edges: floating intakes

Shallow groundwater:

  • Often shallow sources are available but have not been considered as options

  • Borehole drillers tend to disregard significant shallow aquifers:

o Access is cheaper & quicker than deeper water = good for emergency

o Bacteriological & chemical water quality can be very good = less treatment

o Can be good source for tinkering

o Quantities vary - seasonal

  • During your survey, find out where local people get their water from – these are often shallow sources

  • See if these sources can be upgraded or maximised

Open water can be treated at source by:

o Package treatment kits

o Your own treatment kit made up of bits & pieces

Open water can be treated at collection by:

o Household water treatment

Technical options for transporting water

Water trucking:

  • Provides immediate supply

  • Water source can be borehole with gantry or treated surface water

  • Tankers can vary in size (5,000 litres up to 20,000 litres)

  • Need supervision that number of trips on paper is what actually happened – also that each tanker is full and empties completely

  • Chlorination – for clear water, where would it take place? Chlorination impossible into metallic tankers…

Problems with water trucking:

  • High cost – tends therefore to be short-term option allowing you to find other alternatives

  • Availability/ reliability of tankers

  • Quality of source

Pumps and pipelines:

  • Water is sometimes transported from the source to site in other ways

  • One of ...

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Good list, but really only a rough outline :) In addition for surface water the quality can also vary considerably with the season, and for example we had huge issues with the treatment this year in northern Uganda, due to a huge spike in turbidity after the unset of the rainy season.

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Lots more in this book!

https://wedc-knowledge.lboro.ac.uk/de...

far more than can be fitted into a text box - download it and enjoy...

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