The distribution of water to affected communities typically involves tanks, pipes and water distribution points.
The Oxfam Water Distribution Manual is practical advice focused on the type of system commonly used in common emergency situations.
In some places that we work, pre-paid water dispensers may be an appropriate solution for improved financial sustainability and equality of access to water. Oxfam have written a technical brief to provide an introduction to this relatively new but very topical technology.
Design of Distribution Systems
There are a series of books by Sanitago Anaralich which are a good starting point for understanding the design of small water systems. You can read one of them for free here: Gravity Flow Water Supply by Sanitago Arnalich.
The following book by Thomas D Jordan on the subject of gravity-flow water systems in Nepal has been a useful reference text for many years. It is not free to access, however. A Handbook of Gravity-Flow Water Systems
Oxfam Water Tanks
Oxfam Supply Centre have produced a one hour video series detailing how to properly install an Oxfam water tank. A variety of water storage solutions are available on the Oxfam Supply Centre.
Design of Water Collection Points
- Water collection points should be designed to avoid standing water around them; in particular, a proper soakaway should be incorporated to the design.
- The tap stand should be no more than 10cm (4”) higher than the tallest locally used water container.
- Ensure that provision is made for people with limited mobility to access water.
- Users should be consulted on tap stand locations but try to ensure the tap stands are located safely and strategically (near to schools, health and feeding centres etc.)
- Low maintenance requirements and the formation of User Management Committees are essential for building local capacity, improving resilience and sustainability.
- Technical calculations and detailed drawings are required before construction begins.
- Pipe design networks should range between the following values:
- Flow rates to faucets 0.1 to 0.3 l/s
- Tap stand residual heads 4 to 12m (depends on faucet type) Velocity in all pipes 0.3 to 1.5 m/s generally. Refer to the guidelines for the exact figures.
- All PVC/PE pipes should have classed pressure ratings with the minimum 6kg/cm2 (higher pipe pressure ratings may be required depending particular design)
- PVC/PE distribution pipes should be buried a minimum of 0.8m (1.5 in sub zero temperatures). When pipes cannot be buried GI pipes should be used.
- All designs that pass through landslide prone areas should have serpentile or progressive joints for quick isolation, diversion or replacement.
- Gravity designs should include appropriate wash out and air purging points where necessary to ensure the correct functioning of the system.