Toilets, Toilets everywhere, but not one has to stink!
You've heard Samuel Taylor Coleridge's "Rhyme of the Ancient Mariner", paraphrased as "Water, water everywhere, but not a drop to drink". And you are probably aware that in most parts of the world the contamination of drinking water and other fresh water supplies has a lot to do with toilets. Poorly designed toilets. Poorly discharged toilets. Poorly treated toilet wastes.