Spring protection

A distribution chamber set up to protect a spring in the village of Butinduyi, Uganda.

Credit: WaterAid / Jim Holmes

Surface springs occur where groundwater emerges at the surface because an impervious layer of ground prevents further seepage downwards.

The rate of flow of water from the spring will vary with the seasons. It is necessary to measure the spring's flow at the end of the dry season to determine its potential reliable yield.

An inspection of the ground upstream of the spring is essential to ascertain that there is no danger of pollution or, if there is, that measures can be taken to prevent it.

A spring source can be used either to supply a gravity scheme or just to provide a single outlet, running continuously, which is set at a sufficient height to allow a bucket or container to be placed below it.

To prevent waste, any flow which is surplus to that required for domestic use can be used to irrigate kitchen gardens.

If the flow from the spring is not sufficient to meet peak demands during the day, a storage tank can be incorporated into the structure of the spring protection.

This enables the flow from the spring over the full 24 hours to be stored, then used throughout the day to meet intermittent demands by means of a tap in the structure.

Methods of spring protection

Many different methods of getting the clear spring water from its source into the bucket or pipeline are described in the textbooks.

The essential matters are to protect the spring water from pollution, and to arrange for it to be delivered at a suitable level so that it falls directly into a container.

The following points should be considered when investigating a potential spring source:

Making sure that the spring is not really a stream which has gone underground and is re-emerging

Making sure that the source and the collecting area are not likely to be polluted by surface runoff

Checking that there are no latrines within 30 metres upstream of the spring

Fencing the area around the spring tank to prevent pollution by children or livestock

Making sure that if the spring is to be connected to a piped water system it is on higher ground than the area to be supplied

Taking care that the spring tank is not built on swampy ground or on land which is subject to erosion or flooding and that the flow from the protected spring itself will not cause erosion or damage

Typical spring flow rates

An intake chamber and valve box on a protected spring.

Credit: WaterAid / Jim Holmes

A flow in excess of 0.1 litres per second is sufficient to fill a 20 litre container in just over 3 minutes, which is an acceptable waiting time. From such a spring a daily useful yield of about 3000 litres can be expected, which is enough water for about 150 people.

If the flow were to be only 0.05 litres per second it could still can be made to supply the same population by incorporating a storage tank of 1 cubic metre capacity.

If the flow were to be 0.5 litres per second or more the source would be suitable to supply multiple outlets or a piped gravity scheme.

Stages in the protection of a spring

The following three diagrams illustrate the stages in the construction of a collecting chamber:

Stage 1. is a plan view, showing:

A cut-off drain to divert surface water
Clearance of vegetation above the eye of the spring
A temporary diversion of the spring water to allow construction of the collection chamber

Stage 2. is a plan view, showing: