Cost of Rainwater Harvesting System
across the UK

# Rainwater Harvesting System Accreditation Guide

Several UK trade bodies and regulatory schemes govern rainwater harvesting installations, each offering different levels of assurance. The British Standards Institution (BSI) sets out BS 8515:2009, the standard for rainwater harvesting system design and installation, which establishes best practice for safety, performance and water quality. The Microgeneration Certification Scheme (MCS) certifies installers and products for small-scale renewable technologies, though rainwater harvesting typically falls outside its scope unless combined with other renewable systems. The Water Regulations Advisory Scheme (WRAS) approval is essential, as it confirms that systems comply with the Water Supply (Water Quality) Regulations 2016 and won't contaminate mains water supplies. Additionally, many professional installers hold membership with bodies like the Chartered Institution of Building Services Engineers (CIBSE) or are registered with the Institute of Plumbing and Heating Engineering (IPHE), both of which require continuing professional development and adherence to codes of practice.

To verify a provider's accreditation, ask for their specific certifications and check them against the trade body's official register—most bodies maintain searchable databases on their websites where you can confirm membership status and any conditions attached. Request evidence of WRAS approval, which is particularly important for protecting your water supply and maintaining insurance validity. Ask whether the installer has professional indemnity insurance and guarantees in writing, and check online reviews and complaint records with the relevant trade bodies. This verification matters because it protects you legally and practically; an unaccredited installer might undersize your system, fail to isolate it properly from mains water, or leave you without recourse if problems arise. Accreditation also ensures the system is designed to capture, filter and store rainwater safely, meeting water quality standards and reducing contamination risks.