Many people are looking at or actively taking part in some kind of water recycling scheme. Mostly these tend to be personal rainwater systems used to irrigate our gardens. A few more of the ecologically minded people out there may well have implemented rainwater harvesting systems for use within their household systems such as washing machines and toilets. If people are not already at least capturing rain water for irrigation purposes then you really should be. A discussion on Low Carbon Economy byalready exists on the site looking at a number of issues surrounding rainwater harvesting, please take a look.

In Britain although hard to believe if you harvest rainwater depending on the size of your roof and number of people in the house you may have to top up for tank from the mains supply, this obviously isn’t ideal. One way to top up your water harvesting is to utilise your “Grey Water”. “Grey Water” refers to the water used in showers, baths and sinks. This can be then recycled and used in the flushing of toilets quite easily. The questions that have been raised with me are in reference to the ability of any systems to sufficient clean grey water to then add it to the rain water supply. Some systems claim to be able to do this, which obviously provides great benefit to those with rain water harvesting systems already in place. However opinion is split as to whether you really should be mixing grey and rain water in the first place.

A closed grey water system, meaning the water does not enter the overall rainwater system, will dump unused grey water after a certain period of time. This prevents water becoming stagnant, smelling and preventing bacteria from reacting with the biological debris present.

If a grey water system is open then all biological debris will need to be removed (skin, bacteria, hair) before it can be incorporated into the wider system. These pollutants have to be removed to make the water suitable for clothes washing, dishwater water and irrigation. There are a number of questions that are raised in the approach. Some implementers recommend that you don’t mix the grey and rain water for the following reasons:

• Bad smelling water
• Water with high level of bacteria present might not be suitable for washing clothes
• Residue being left in the water tank will need cleaning out more regularly
• Hair from grey water will clog up pumps around the house/appliances

Without chemically and mechanically cleaning the water, there are doubts as to whether or not just gravity alone pushing the grey water through filters can sufficiently clean the water to the required standard. Presently based on the weight of opinion I’ve polled 2 consistent points have come through:

• Yes use grey water as it is a thoroughly useful resource
• Do not mix grey and rain water

Can any suppliers/installers of the grey water filters shed any light on this subject as to previous installations and the capabilities of their products? Are there any homeowners out there that have a similar system in place now?