This is not meant to be a trick question because the answer is No… but why is that?
Collecting rainwater is not regulated in the slightest but what you do with it afterwards most certainly is if you intend to pipe it into a building or make it available for public consumption.
The critical aspect is that it must be clearly labelled as non-potable and must never, ever be allowed to backflow into the public mains water system to safeguard drinking water supplies.
Characteristics Of Rainwater vs Public Mains Drinking Water
Rainwater is essentially untreated water. That means it almost certainly contains contaminants or microbial agents, and possibly pathogens. Even rain that falls straight from the clouds will more than likely pick up particles of dust or fungus that float in the atmosphere. As rainwater harvesting usually collects water from rooftop surface areas, it is typically contaminated with bird and rodent droppings as well as dirt and dust blown by the wind. In short, it is not clean water and far from drinking water quality. It can easily be filtered to remove most physical impurities but would need to be treated in some way; e.g. ultraviolet light, or chlorination to destroy bacteria and pathogens.
What Are The Recommended Or Permitted Uses For Harvested Rainwater?
It may safely be used for purposes where there is no risk of contaminants endangering public health. That includes applications such as vehicle washing, toilet flushing (27% of domestic water consumption is flushed down the toilet), gardening and irrigation, washing machines and general outdoor washing such as cleaning pathways. Rainwater is also widely used in farming. However, it is not suitable for dishwashers, showers or bathing unless treated.
What Are The UK Regulations & Guidelines That Govern Usage Of Harvested Rainwater?
There are three sets of laws or guidelines that need to be taken into account when planning a project that supplies harvested rainwater for consumption.
1) Water Supply (Water Fittings) Regulations
Each UK country has its own laws pertaining to water supply. They apply to every premises to which the public mains water supply is connected and are enforced by the 26 UK water companies. The primary thrust is to prevent contamination and they cover the design, installation, operation and maintenance of appliances that consume water, plumbing, fittings and also consumption levels. Essentially, everything to do with using the water supply from the point of connection to the mains. Find out more on the Water Regulations Advisory Scheme (WRAS) website, which is a limited company that has all the water suppliers as shareholders.
2) The Building Regulations
These govern all aspects of construction. The relevant sections relating to water are:
Part G – Sanitation, hot water safety and water efficiency
Part H – Drainage and Waste Disposal
Find out more on the National Building Specification (NBS) website.
3) British Standards BS EN 16941-1:2018 Rainwater Harvesting Systems Code Of Practice
A set of recommendations (not legislation) aimed at the rainwater harvesting industry covering designing, installing, testing and maintaining these systems. It applies to supplies of non-potable water only in public, industrial, commercial and domestic buildings.
They can be purchased on the British Standards Institution (BSI) website:
BS EN 16941-1:2018
Title: On-site non-potable water systems. Systems for the use of rainwater.
Speak To Us
As a professional engaged in, or supporting, the construction industry, you need to be aware of the above regulations and standards. Always seek the advice of experts in the rainwater harvesting industry such as us at Rainharvesting Systems, the UK’s oldest systems supplier.
