Process — A solar-powered water pump and filter

The diagram explains how a system driven by solar energy raises water from beneath the ground and purifies it for use.

Overall, the process consists of seven steps and falls into two phases. In the first, electricity generated from sunlight powers a pump that lifts groundwater to a raised tank; in the second, the water runs down through a filter and out of a tap.

To begin with, a solar panel mounted on a pole converts sunlight into electricity. This current passes to a control unit at ground level, from where it is sent down a cable to an electric pump positioned 40 metres below the surface, in a layer of underground water. Once the pump is running, water is drawn up from this layer and rises through a vertical pipe.

At the top of the pipe, the water enters a storage tank that stands on a tower and holds 5,000 litres. From there it flows down by gravity into a filter unit, where it passes through three layers: first gravel, then sand and finally charcoal at the bottom. In the last step, the clean water leaves the base of the filter along a short pipe and is dispensed from a tap.