flush it all away - to where?People are so funny. They're embarrassed about 'bodily functions' so there are lots of cute or coy ways of talking about places for getting rid of the body's waste products; names like ladies, gents, mens' room, little girls' room, powder room, public conveniences, the john, heads, the bog, the loo. I'm sure there are many more. But they all mean one thing: a place to get rid of rather smelly waste. Dumped, flushed — out of sight, out of mind. Phew!

Urine and faeces are the polite names for the liquid and solid wastes that come out of every body, but there are many more, mostly rude!

But in nature, there's no such thing as waste. The stuff people flush down toilets could all be used as fertiliser for growing food. But mostly, it just gets thrown away into rivers, lakes and the sea, making more pollution.

All this flushing causes another problem. Toilets use a lot of good quality water. Many countries don't have enough water so flushing toilets are a big problem. There are other types of toilet which use little or no water and also produce good quality compost &mdash: food for plants. But most people don't like them because they are used to flushing and think that any alternative must be smelly and disgusting. While that used to be true, it isn't any more.
Yukky or not?
Waste from toilets is called 'sewage'. Some of this is used as an excellent fertiliser for crops, but only after careful processing to break down any harmful organisms it might contain. But much of it isn't used because it's cheaper not to bother. And some can't be used because of heavy metal contamination from industry. So sewage often gets dumped into rivers and the sea in a raw or partially treated state.
Sewage causes obvious smelly pollution while swamping the rivers and seas with far too much nutrient. Nutrient is food for plants but too much of it can kill off almost everything in the water, especially fish and corals. It can also cause microscopic plants called algae to grow into massive blooms which cover everything in often-poisonous slime. This type of pollution has a special name: eutrophication.

What amazes me is that people throw most of this natural plant fertiliser away and then spend vast amounts making artificial fertilisers. Places like Nauru Island have been destroyed by phosphate fertiliser mining. And artificial nitrogen fertilisers need energy on a vast scale. The energy comes from fossil fuels... which then pollute the atmosphere and cause climate change.

Nauru is a small island in the southwest Pacific Ocean. It was once covered in a thick layer of phosphate rock, built up over thousands of years from decayed oceanic microorganisms and bird droppings. This has all been stripped bare by mining because this rock is a valuable fertiliser for farming. The result is a parched bare rock moonscape with no soil so no vegetation, and serious problems for the people who live there.
Fixing nitrogen
Plants need nitrogen (chemical symbol N) to grow well. They also need phosphorus (chemical symbol P; from phosphate rock) and potassium (chemical symbol K). So artificial fertilisers are a mixture of the three: NPK. The nitrogen for the NPK fertilisers comes from the air &mdash: free, you might think &mdash: but there's a huge energy price to pay for changing it from nitrogen gas into the nitrate needed for plant fertiliser. Some plants &mdash: legumes like clover, peas and beans &mdash: can 'fix' their own nitrogen using the sun's energy so they don't need artificial nitrates. Organic farmers grow a lot of legumes for most of their nitrogen needs.

So people pay twice: first, to throw away body 'wastes'. Then they pay again to make fertiliser by using stuff which will run out in a few years. Crazy, isn't it?