The British Code of Practice for Rainwater Harvesting systems (BS 8515) that was in force since 2009 was superseded in 2018 by BS EN 16941-1:2018. For professionals in the architectural, design and construction industries as well as suppliers of rainwater harvesting systems, appreciating its thrust and recommendations is a must. Failure to adopt it at planning and design stages could easily result in breaches and see planning applications being rejected for possibly minor details.
What is it all about?
It relates to on-site non-potable water systems where the capture and recycling of rainwater is used as an alternative to using mains water. This is generally for non-potable applications such as vehicle washing, irrigation systems, flushing toilets, laundry, sprinkler systems and other uses where the water is not ingested.
BS EN 16941-1:2018 Rainwater Harvesting Systems is a recommended Code of Practice that sets out to deliver consistent installation standards and water quality. It covers these aspects of industry practices for non-potable systems:
- Ongoing care and maintenance of the system
- Risk management
- Recommendations to systems suppliers
What are the most significant sections that I need to know about?
From a practical point of view, the design and installation activities receive the highest proportion of attention, which makes sense;
Design – Designing a rainwater harvesting system for a building is quite a complex activity, which surprises many who are approaching it for the first time. It requires factors and calculations to be considered such as:
- The application and number of users (e.g. vehicle washing V toilet flushing in an office block)
- The rainfall profile of the part of the country (e.g. Manchester V East Anglia)
- The nature and surface area of the collection surface
- The volume and location of storage tanks – usually underground
- Pumping requirements based on the application and number of users
- Any characteristics of the site
- Satisfactorily balance yield V demand
- Cater for the demand profile (peak periods)
- Calculate flow rates
- Overflow handling
- Backup fill from mains should supply become exhausted
Storage tanks must prevent microbial and algae growth and avoid stagnation or conditions where Legionella could develop.
Installation – The main thrust of the guidelines surrounding installation is the critical need to keep non-potable supplies separate and distinct from drinking water. Not only are separate circuits and pipes required but there must be no possibility whatsoever of cross contamination. Very clear labelling is also stressed as being important, both of pipework and of outlets.
The regulations complement those sections of the Building Regulations that specify how mains drinking water supplies should be connected to a building.
Get in touch
When considering a rainwater harvesting system to enhance the attractiveness of your next project or development, it pays to consult first with the experts. We at Rainharvesting Systems have a wealth of experience in all aspects of design and installation, including understanding what pumping, storage and filtration systems are most suitable for a given application. Please contact us for a free initial consultation to discuss your proposed project.