Sanitation means rather more than keeping the sewage out of the water supply. In most villages the only place to 'go' is in the bush. Girls often don't like to go into the bush by day; so they wait uncomfortably for darkness, and then risk being attacked by animals - or by men. Pigs can wait to snuffle up the excrement, which is frightening for small children.
If there are no proper lavatories at school, girls will stay away, and miss out on their education.
The solution is the latrine - ranging from a small hut with a seat over a hole in the ground to the ventilated improved pit (or VIP) latrine.
These perform several functions. First they provide privacy and safety for the users, often close to their homes, rather than hundreds of yards away in the bush. Second they keep the sewage away from water supplies. Third they protect the sewage from flies, which would otherwise settle on it and carry dirt and disease into the houses.
Some latrines are also designed so that the sewage can be composted and later used for fertilizer, as Omar Salima, a farmer in Matamangwe village, Mozambique explains:
"The compost produced has increased our yields and is producing better quality crops. Now we not only have enough food for ourselves but we have extra crops to sell. Maize, lettuce and peppers do best - they don't just wait in the ground, they shoot up just like that! In the past we had to buy artificial fertiliser and we could only afford to open a small field - just three hectares. Now we are able to farm 13 hectares.
I don't use much manufactured fertilizer on my garden - pelletised chicken manure for the potatoes and that's about it. I compost my kitchen waste and use that. The flower patch is 'cottage garden' style - untouched and manages itself.