Greywater is waste water from baths, showers, and so on which can be used to water plants and wash cars amongst other things. In almost all homes this expensively treated water goes straight down the drain and into the sewerage system to be expensively treated again. At the same time there are currently hosepipe bans across many regions in the UK and water usage meters are being fitted to many homes.

Saving and recycling greywater is a cheap and easy way to save energy and save money. In conjunction with rainwater collection, and a simple irrigation system gardens, greehouses, and polytunnels can be watered entirely from recycled water.

Collecting Greywater

The simplest way of collecting greywater is to simply an equal tees waste pipe splitter (pictured above) into the bathroom wastepipe before it joins the sewer pipe. All water from showers, baths, and the sink can therefore be diverted to your greywater storage vessel.

This is by no means a perfect scheme though. For example, if you clean the bath out with chemical cleaners, they will be washed down and into your greywater tank. Small amounts of bleach will do no harm, but if large amounts of harsh chemicals build up in the greywater tank together with soap and shampoo etc, the collected water will not be good for the garden.

Therefore an ideal system will give you a way to decide whether the water going down the plug hole should be sent to greywater storage, or straight down to the sewers (or septic tank). If you are putting chemicals down the plug, if your greywater storage vessel is full, or in a hard frost all waste water should be sent to sewerage rather than being collected. This is achieved using a greywater diverter valve.

Greywater Diverter Valves – Interior Plumbed

Pictured above is an example of a great three-way greywater diverter valve available in the USA for $49. This device (Jandy Never Lube Three Port Valve), a fairly typical robust greywater diverter valve has three ports – one through which the waste water enters, one which is connected to a pipe going to sewerage, and one which goes to greywater storage. A simple manual switch is fitted which is simply rotated to select between sewerage and storage. Such a diverter valve should last a lifetime.

Pictured below is the Never Lube Three Port Valve fitted in a typical home plumbing system.

Greywater Diverter Valves – Exterior Plumbed

Pictured below is the Water Two greywater diverter valve (designed in England by Water Two UK LTD. This simple device – available in the UK for under £30 is fitted to the bathroom waste pipe outside the home just before it meets the main (sewerage) down pipe. Pull cords are fitted to control the device – pull one cord down to send all waste water to the down pipe, pull the other cord to send it to greywater storage.

Diverted water is sent down a standard hose pipe to the greywater storage vessel – water butt or tank. Installation should take a fairly incompetent DIYer under an hour.
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Ideally the collected water should be passed through a suitable greywater filter before it is stored. A couple of tablespoons of chlorine bleach per gallon of stored water will disinfect it and prevent it from stagnating.