Report No DWI0778

GREYWATER AND RAINWATER SYSTEMS: RECOMMENDED UK REQUIREMENTS Final Report 13034/2

DWI0778

Mar 1997

Executive Summary

This report summarises proposed water quality standards and conditions of use for recycled greywater and stored rainwater systems in the UK. The study, on which the conclusions presented here are based, was carried out by BSRIA, during the period October 1996 to February 1997, for the Drinking Water Inspectorate of the Department of the Environment. Full details of the research are contained in BSRIA Final Report 13034/1 dated March 1997, available from BSRIA Publications.

An important constraint on the uptake and use of greywater reuse and stored rainwater systems in the UK is perceived risk to public health. This is particularly so for greywater recycling systems, as there is a possibility that greywater, having been in contact with humans before its reuse, may contain low levels of faecal contaminants. Such concerns have led a number of authorities outside the UK to severely restrict the types of greywater recycling system that are permitted. However, due to recent advances in wastewater treatment technology, experience gained elsewhere, and because public health risks are very application-specific, it is considered unnecessary to impose similarly restrictive regulations on the end-use of recycled water in the UK. Instead, it is proposed that individual systems be tested to an agreed standard, by an accredited test-house, before they can be sold or installed. It is also proposed that water quality criteria appropriate for such systems should be application specific.

Suitable application-specific water quality standards for the UK are proposed in this report, based on relevant standards from the UK and overseas. In addition, the report summarises general requirements for the design, construction, operation and maintenance of UK systems, necessary to protect public health and minimise deleterious effects to plumbing systems and the environment.

The detailed, separate report, referred to above, also provides information on systems currently marketed or under advanced development and includes a comprehensive economic analysis of the application of recycled greywater and stored rainwater systems in five building types, using six generalised system types, two toilet cistern sizes and both new-build and retrofit situations. It also contains details of user acceptability issues, which published reports from overseas and experiences from the limited number of systems already installed in the UK, suggest will not be a problem if systems are designed, installed and operated correctly.

The only factors now limiting the wide-scale use of such products in the UK are perceived lack of economic benefits and water quality assurances. However, the use of greywater and stored rainwater technologies will become increasingly popular as water charges rise; as a recognised system of accreditation, to verify the safety and performance of such systems, is introduced; and, if designers, suppliers, installers and users adhere to the guidelines presented here.

Copies of this report may be available as an Acrobat pdf download under the 'Pre 2000 Reports' heading on the DWI website.