Latrine Technology

What type of loos are being built?

It’s really important that latrines are appropriate for the people who will be using them and the context in which they live. Ours is not a one-loo-fits-all approach.

So our partners spend time talking with communities to help them choose the right design. Latrines need to be built in the right place too, so they don’t contaminate water sources, and we make sure that materials and methods are as environmentally sensitive as possible too.

These are the basic latrine options, where water for flushing is not available:

The simple pit latrine

This is the cheapest and most basic form of ‘improved sanitation’. A pit at least 1.5 metres deep is covered with a cover, slab or floor with a hole in it. The hole is covered with a lid to contain smells and flies, and the latrine is covered with a shelter. When the pit is full to within 0.5 metres of the hole, it is topped up with soil. Then, a new pit is dug and the slab and shelter can be reused.

The ventilated improved pit (VIP) latrine

This is a variation on the simple pit latrine but features a vertical ventilation pipe to remove bad smells. There’s no cover to the hole, to allow a flow of fresh air through the latrine, but the pipe has a mesh cover to keep out flies.

The twin-pit ventilated latrine

This is a variation on the ventilated pit. Two pits with squat holes are dug side by side and the shelter covers both holes. Only one pit is used at a time so the other squat hole is closed. Once one pit is full, it’s sealed and, after a year, its contents can be used as manure (see below). The ventilation pipe is moved to whichever pit is in use.

Where water for flushing is available, there are even more options:

The pour flush latrine

These latrines have a special pan cast in a cover slab above the pit, which provides a ‘water seal’ to contain bad smells. The pit can be directly below the hole or ‘offset’ so that, for example, the latrine can be inside the home and the pit outside. Offset pits require a pipe to be fitted between pan and pit – and need more water to flush. It’s also possible to have two pits so that, when one is full, the other can be used.

Composting latrines and humanure

The composting latrine

This latrine differs from others because the pit is watertight and ash or vegetable matter are added to the pit after each use. After a few months, if the moisture content and chemical balance are properly controlled, the pit contents make good soil fertiliser for agriculture.

It can take time for people to come round to the idea of using ‘humanure’, and we use village champions and demonstrator household to promote the concept. Where we are already using composting latrines (eg in Uganda and the Democratic Republic of Congo), they bring many benefits, in addition to a ready supply of fertiliser. The pits are used cyclically, with some sealed for decomposition while others are opened, so they can be shallower. That means they are easier to dig and there’s less chance of contaminating the water table.

Greening latrines

Being environmentally sensitive is very important to us. Using concrete is not our preferred option for lining pits – but sometimes it is unavoidable. It is used in areas where the soil is unstable (and the pit would collapse without it) or where pits need to be particularly robust, such as in school blocks where cubicles and their pits are close together and are emptied regularly.