National Recycle Week – Day 2
Today, on this dry and sunny day, I’m thinking about water.
Water is one resource that gets naturally recycled: clouds drop rain on the earth, which gets soaked up by the soil, used by plants or flows into lakes or the ocean, before some of it evaporates to form clouds again. Round and round it goes, sometimes being stored, sometimes being created (all living things make water when they respire, and it’s released during combustion) and sometimes being used as a building block (plants use water along with carbon dioxide in photosynthesis to create carbohydrates). This global cycle carries on unnoticed for the most part, although humans do interfere with it, for example by extracting water stored underground or by channelling it so that it flows quickly through the landscape and doesn’t soak into the earth.
Humans also, however, pollute it. We use it to wash away waste, thus requiring some sort of treatment before it can safely be returned to the environment. So, we need sewage treatment plants and tailings pools and filters and all sorts of other ways of cleaning up the water we have used. Sometimes we also make it warm and then discharge it directly into the environment, thus upsetting the natural systems in the area (this is known as ‘thermal pollution’ and is a particular problem with power plants and industries that use water for cooling)), at least in part because warmer water contains lower levels of dissolved oxygen.
On a more personal scale, it’s interesting to consider the water we use in our own homes. In most cases, there’s not a lot of cycling goes on in this context, but we can be much more efficient with our water use and make sure that we contaminate as little of it as possible. Generally in domestic situations, our biggest source of contamination is sewage – every time you flush the toilet, you send 5-10 litres of polluted water down the drain, and that water will have to be processed (thus using energy) before it is safe to release back into our rivers and seas.
The best thing we can do as individuals is to reduce our water use, using our water as many times as possible before sending it out of our homes. Grey water – such as what comes out of the washing machine – can be used again to water plants or wash the car, thus doubling up on use and reducing the amount that needs to come out of the mains (which will save you money too if your water is metered). Chez Snail, we collect lots of rainwater for use around the house and garden and this means that, wherever possible, we are not using the processed water that comes out of the taps for jobs that don’t require it. For example, all the concrete that has been mixed during our building work has used rainwater… after all, it made no difference if it was a bit gritty or contained some algae.
It’s even possible to build your own little gray water treatment plant at home if you wish. I have a book entitled Toolbox for Sustainable City Living that provides detailed instructions on building a wetland out of three recycled bathtubs to filter washing machine waste water… it’s not the answer for all of us, but if you live in a city and want to process your water for re-use there are options. Chez Snail we will continue to water the plants with our used washing-up water and flush the toilet with rain water and grey water and in these ways we will help mother nature in her grand recycling operation.