C. Water supply

Different types of water

Potentially, three types of water may be available:

SURFACE WATERS: STREAMS, RIVERS, LAKES, PONDS, RESERVOIRS (DAMS)

- It is generally heavily polluted particularly during the rainy season.
- Its quantity varies with the season.
- It generally needs complex treatment before use. Nevertheless, certain catchment methods allow a significant improvement of water quality: shallow wells dug close to river banks, river bed filters, infiltration galleries.

GROUNDWATERS: WELLS, BOREHOLES, SPRINGS

- Deep groundwater (boreholes, deep wells, certain springs):

· Generally clear and of good bacteriological quality (filtered by percolation
through rocks).
· Sometimes containing substances rendering it undrinkable because of its taste or because of toxicity.
· Not generally subject to much seasonal variation in quality or quantity.

- Shallow groundwater (wells a few metres deep, certain springs, groundwater near water courses):

· The higher the water table, the lower the bacteriological quality tends to be (water from less than 3 metres deep should be treated like surface water).
· Subject to seasonal variation in quantity.

RAINWATER

- In non-industrialised regions, rainwater is relatively pure and may be consumed without treatment as long as it is collected with certain precautions, ie on a clean surface (tin roof, tent, plastic sheeting) and the first flow of water is rejected.

- Although rainwater rarely provides a regular supply, it may sometimes be a useful temporary or complementary supply (it may be a good alternative to heavily polluted surface water during the rainy season).

Warning !!!

- The exclusive consumption of rainwater without a complementary intake of essential minerals (such as iodine) causes problems in the long term.

- Rainwater dissolves the metal in which it is stored. Do not use containers or pipes made of copper, zinc or lead: clay, cement or plastic containers are suitable.

In practice there is rarely a choice between these different sources of water, particularly in emergency situations.

When settlement begins, surface water (the most polluted or the most easily polluted) is often the only supply available. It is therefore imperative to concentrate on the problem of water as top priority.

Sometimes, at first, supply by water tanker is the only solution. Other solutions should quickly be planned: drilling, digging wells, moving the camp, etc. (specialist advice will usually be needed).

Sometimes a piped supply from an urban area may be possible.

Priorities

What are the priorities in terms of water supply, when dealing with a concentrated population?

Before anything else:

- Find out where and how the people go to collect water and where they defecate.

Then:

- Designate defecation areas far away from water points.
- Distribute water containers if necessary (very important).
- Take specific steps to protect water points.
- Determine the amount of water available.
- If necessary, set up a water rationing system.

Finally:

- If necessary, increase the output of the water points or look for additional sources of supply.
- Create a reserve water stock.
- Improve measures to protect water points.
- If possible, set up a system whereby water is pumped into reservoirs before being distributed.
- Check water quality if necessary.
- Possibly, install a treatment system.

WATER POINT PROTECTION MEASURES

All the protection measures aim at preventing the introduction of fl genes into the water (either directly, or indirectly by run-off or dirty soil falling into the water, etc.).

- Protection of water courses

Organize the use of the water course according to environmental health considerations. The point used for collecting water should be upstream of all other uses.

Note: surface water is always difficult to protect (there may be a village upstream). As soon as possible, use other sources (wells, springs, boreholes), or at least, pump the water so that people and animals do not have direct access to the water course.

- Well protection

Immediately (and this does not require any particular materials or skills):

· Employ a watchman to monitor access to the well.
· Surround the well with a fence against animals. If it is used to water animals, make a channel to take water to a trough situated outside the protective fence.
· Forbid the use of personal water containers: one rope with a single container should be provided for this use.
· Install a winch or similar system so that the bucket and rope are not laid on the ground and so that people do not lean over the well.
· Keep sources of pollution such as latrines at least 30 metres away from the well and downhilI from it if there is a slope (caution: in certain hard and fissured rocks, 30 metres is not enough).

As soon as possible:

· Make the improvements needed to prevent infiltration of run-off (make the upper part watertight to at least 3 metres depth, install an apron, a concrete slab on the head wall, and drainage of the surroundings, etc.).
· Cover the well and install a handpump or a self-priming motorpump (plan for maintenance and the supply of spare parts).

- Spring protection

Immediately:

· Install a system which prevents water from standing at the spring (collect the running water with a split bamboo, for instance).
· Erect a protective barrier around the spring (10 metres above it).
· Dig a drainage channel 10 metres above the spring to avoid it being polluted by run-off.

As soon as possible:

· Build a spring box.

Certain measures for the protection of water points can, and should, be taken during the very first days. Others require particular materials, equipment and skills, and should only be envisaged at a later stage, though as quickly as possible.

Do not wait to be able to solve the whole problem before starting work; every step taken is an improvement.

Note:

Fl pollution of water may occur at any stage between its origin and its consumption. For example, for water from a well there may be:

- pollution of the water table,
- pollution of the water inside the well (from soil, run-off, etc.)
- pollution during transport (from dirty containers, dirty fingers, etc.),
- pollution during storage in the home (from insects, dust, people taking water with dirty recipients, etc.).

Consumption of clean water can only be achieved by action at all levels, with a global programme of water point protection, excrete control and health education which is a long term programme).

Pollution at the source or during collective transport is nevertheless more dangerous than pollution in the home, because it affects the whole population at once and consequently encourages large scale epidemics.

CONTAINERS FOR TRANSPORT AND STORAGE

If the displaced people have not been able to bring enough containers with them they cannot use the water which is provided for them.

Each family should have containers with a total capacity of 40 litres as a minimum.

If the people do not have enough containers, it is vital to distribute them as a top priority.

Containers with small openings (like jerrycans) with a cap are the most suitable because they are used by pouring the water and not by dipping into it (which risks contaminating it each time).

Cooking oil is often distributed in such cans, and they can be re-used.

Traditional clay containers may be suitable as long as they are covered to prevent contamination by dust and insects.