Why does the toilet roof need replacing?

We built the toilets with the Alavanyo Dzogbedze community in 2019. They are well used – with people coming & going throughout the day. A recent survey found that at least 326 people and children are using the toilets, preventing diseases and providing dignity. But, unfortunately, the roofing on the female side has pretty much disintegrated.

Destroyed roof


We used aluminium sheeting for the roof to keep the cubicles cooler, the shiny aluminium reflects the sunlight. It should have been strong, rust free and lasted for years, in all weathers. But we didn’t consider the chemical reaction of the gasses in urine.

When urine decomposes it produces ammonia gas. At night, there is condensation on the underside of the roofing sheets which dissolves the ammonia, creating ammonium hydroxide. This ammonium hydroxide reacts with the aluminium to produce aluminium hydroxide, which is soluble. When the aluminium sheet on the roof turns into aluminium hydroxide it dissolves the roofing sheet and is washed away by the rain. In short: the urine dissolves the aluminium sheets.

The men’s side of the toilet block was not corroded at all. As we know, is far easier for men to wee, discretely in public, so they tend to only use the toilets for defecting. Whereas women need the privacy provided by toilets every time they need to go.

Good news

Removing the old roof

The good news is, now we have identified this, we have replaced the roofing. This time with galvanised iron sheeting which should last for many years. We will, of course, keep checking if our hypothesis is correct.

New roof


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