I recently took my daughter to a children's party on a city farm near us. Amongst other attractions was a compost toilet where, as you would imagine, you can contribute in your own special way to a compost heap which then presumably gets used to fertilise some crop somewhere.

It's a good idea, and not a new one. The Chinese have used compost toilets for centuries, and in Hunza, the beautiful valley of longevity in Pakistan, they are an essential part of the whole cycle of health and sustainability. Composting human waste is an efficient, eco-friendly way to put back into the soil what you take out, enriching it with minerals and other fertilising nutrients and avoiding the whole sewage issue.

If you find the idea unsavoury, just remember that all matter is simply a re-arrangement of atoms from some other previously-existing matter, which will one day become part of another arrangement. The atoms in my left toe were probably once part of a dinosaur's ear for all I know, and after I'm gone they'll be part of a cloud, or something. Likewise, food becomes human waste, which becomes compost, which becomes plants, which become food. At least it does when you have a compost toilet.

A quick search on the internet reveals that there is a wide range of these useful devices available to those of us in the West who may have similar leanings to those canny Hunzakuts and Chinese. In terms of creating a hygienic end-product, modern compost toilets fall between two stools – although hopefully the same fate does not befall the user – hot or low temperature, so that pathogens are either heated enough or left long enough to be broken down. Either way, what you are left with doesn't smell and you only have to empty it once a year.

Compost toilets used on a wide scale could help with the growing problem of what to do with all the sewage we produce, because they protect groundwater from contamination, save vast quantities of water, reduce the need for infrastructure, and produce environmentally sound fertilizer – all important assets given the current state of our planet. Why aren't we all using them, I wonder? I'd like to think that, where the problem of sewage is concerned, the future's in the can.