The title grey water harvest is possibly a means of owning a personal type of treatment plant for sewage etc. and all this is done what is called grey water (and rainwater) harvesting. Now who would have thought that you could take all the wastewater that is produced from your sinks, wash basins, and your bath and shower too. This would then be fed to a storage tank, you could take waste as well, however, you would have to make sure that oils and food waste were not washed down the drains. Putney Plumbers can advise on grey water. When it arrives in the tank, the waste sediments out, with the lighter of the scum floating to the top and running down a drain. There is heavier sediment also and this will fall to the bottom of the tank and is every so often flushed away to the soil stack. In the middle of the tank you now have relatively clear water, wholly unsuitable for drinking but fine to flush a toilet. In reality, things are a bit more complicated. For example, you can’t store this water for longer than 26 hours before the risk of bacteria buildup, so the system will need to be flushed automatically before this limit is reached. You also need the back up of mains cold water fed from a tank via an air gap and a weir overflow, and would probably be built into the system, for when grey water is not available. The positive side of these types of systems is that there is no need for a large tank buried in your garden, which means that the complete installation cost would be low. The negative is that you don’t collect as much water there is a risk of foul smells coming from the flush water itself. A Putney Plumber uses safe practices.There is no real reason why you couldn’t combine grey water and rainwater harvesting, so the grey water supplies the water for the toilet and the rainwater used in the garden and perhaps the washing machine.