Scheme Summary

This is a pilot study into the recycling of grey water and rain water at Perranporth. 8 houses have varying combinations of water recycling and storage, and 10 houses have standard installations and are used as controls.

Scheme Details

Grey water recycling

Statistically we use a similar amount of water for washing as we do for flushing the toilet. Based on this information a duplicate waste water and supply system is installed to collect the waste water from the bath and wash hand basin and recycle it for use in flushing the toilets.

Any discrepancy is made up by the mains water connection or rain water in a combined system. The system used here is the Pressure Butt and this is manufactured by Water Dynamics Limited. Waste water is stored in the Pressure Butt, which is external, then treated and filtered before being pumped up to a typical storage tank in the roof space.

Rainwater recycling
The rainwater is collected in either an underground or above ground storage tank and then pumped through a series of filters and an ultra-violet treatment system to an additional storage tank in the roof space. This provides non-potable water for all hot water usage and flushing of toilets.

The table below shows the actual installations:

Plot no. Greywater
Above ground
House type
1 Yes - Yes No 3B5P(K)
2 Yes Yes (C) Yes No 2B4P(J)
4 No Yes No Yes 3B5P(K)
5 Yes Yes* No No 3B5P(K)
6 No Yes No Yes 1B2P(B)
7 No Yes Yes No 2B4P(J)
8 Yes No N/A N/A 3B5P(K)

The systems were demonstrated fully to housing staff and the management team prior to handover, with a subsequent separate demonstration for incoming tenants. The systems themselves require little tenant involvement and maintenance should be included within the annual maintenance of boilers.

Each system is separately metered, readings being taken monthly. In order for an accurate picture of usage to be built up it is intended that tenants provide information and unusual occurrence such as holidays that may affect the water usage.

Cost Implications

The typical cost for the Pressure Butt system is approximately £2,400 and the rainwater recycling system ranges from £2,800 to £4,850 depending on its size and the method of storage used. The overall cost of installing the systems and metering and maintenance for 24 months is £25,000.

The payback period, depending on South West Water charges and usage is anticipated to be between 9 and 16 years.

Devon & Cornwall Housing Association's opinion

"So far, keeping my fingers crossed, the systems have been used by the tenants without any problems but a full review will be carried out in May of next year". Phil Spencer - Development Operations Manager.

Contact: Phil Spencer,
Devon & Cornwall Housing Association Ltd,
The Mount,
Paris Street,
Exeter, Devon
EX1 2JZ.
Tel: 01392 52566
Fax: 01392 52425