In a first for the UK water industry, British Water has published a code of practice for assessing surface water treatment technologies. The Environment Agency and manufacturers of surface water treatment devices have supported the document, which took over two years to develop.
British Water members ACO Technologies, Hydro International and Polypipe joined with the environmental regulator to sponsor an in-depth study of UK rainfall by research consultancy HR Wallingford. The information was key to the development of a robust product testing protocol.
“Standards are necessary to demonstrate how well proprietary devices used in sustainable drainage systems (SuDS) treat run-off and remove heavy metals from the water cycle. Until now, there was no standard for testing in the UK,” said Marta Perez, Technical Director, British Water.
The voluntary code of practice allows professionals delivering SuDS to apply a risk-based approach to minimising the environmental impact of the diffuse pollution from runoff. Verifying the capture and retention capabilities of different devices for a range of pollutants gives regulators, designers, specifiers and local authorities the information they need to select the most appropriate technology in a given application.
“Conducting tests overseas creates a heavy cost burden which was prohibitive for smaller UK manufacturers looking to sell at home,” added Perez. “This code of practice defines the process necessary to measure the pollutant capture and retention capability of any device entering the UK market.”
The tested devices are typically used to treat runoff from urban and residential hard surfacing such as roads and car parks. Part of the code of practice is aimed at determining three functional requirements of treatment devices:
- Typical pollutant capture efficiency for frequent, sub-annual rainfall events
- Sediment retention capability for up to 1:2 year rainfall events likely to cause washout
- Capability of filter media to retain dissolved pollutants under the influence of de-icing salt
“The tests can be completed by the manufacturer or at a commercial test facility but must be witnessed by an approved independent UKAS-accredited third-party,” said Perez. “British Water is now seeking a partner in the position to install and run testing equipment.”