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Guidance from Building Regulations: Mains Water Supply

Guidance from Building Regulations: Mains Water Supply


At Coastal Drains, we are passionate about what we do and we want our customers to be as informed about their drainage systems as possible. This includes covering bases such as the Building Regulations on mains water supply, and what every property should legally have available in terms of clean, running water for any kind of use. We’ve put together a guide to help this, so that customers with any questions on mains water supplies can find out more.

Read on to find out everything you need to know about the Building Regulations and what it says on mains water supplies, or get in touch with us if you’ve been having trouble with your own drainage system. We can be there in no time at all to make sure the problem is taken care of, using the latest equipment and offering you the most budget-friendly price possible.

What is Says in Building Regulations About Mains Water Connections

In terms of the Building Regulations, mains water supply is covered under Part G. Each part of the Approved Document covers a different water-related topic, each of which help to satisfy the requirements of the Building Regulations. These range from cold water supply and sanitation to hot water safety and water efficiency, and provide both owners and contractors with full guidance on what needs to be covered whenever a property is renovated or a new building structure is put together. Overall, the document is composed of six parts, with two amendments that came into effect in 2016.

Approved Document G of the Building Regulations covers:

  • G1: Cold water supply; meaning there must be a suitable drinking water supply, as well as water for cooking, washing and bathing purposes. There must also be water available in any room with a sanitary convenience that has a flushing device (i.e. a toilet).
  • G2: Water efficiency; meaning the amount of wasted water should be minimised where possible.
  • G3: Hot water supply and systems; meaning a property should have a suitable installation that safely supplies hot water for bathrooms and kitchens.
  • G4: Sanitary conveniences and washing facilities; meaning every property should provide occupants with adequate sanitary facilities, including conveniences such as toilets, and spaces suitable for washing hands. These should also be separate from any kitchen or space where food is prepared.
  • G5: Bathrooms; meaning every building should provide a bathroom that contains a washbasin and either a fixed bath or shower.
  • G6: Food preparation areas, meaning a suitable sink should always be provided in areas that are going to be used for cooking.

Appendix A: Water Efficiency Calculator for New Dwellings

This addition to the Building Regulations on mains water supply adds a method of assessing the level of “potable” (drinking) water consumption in a new house. The appendix was added in order to ensure compliance with the water performance targets set out in the Building Regulations. However, it is only to be used as a guide, as it cannot predict how much actual water will be used daily by a property once it has occupants. 

It should also be noted that this calculator is not to be used as a design tool for water supplies or drainage systems for properties.

Appendix B: Wholesome Water

Wholesome water refers to water that complies with the regulations made under Section 67 of the Water Industry Act 1991. This means that the water is safe and fit to use for drinking, cooking or washing without any danger to human health, in terms of biological, chemical and physical quality (it has safe levels of bacteria, minerals and is the right colour, flavour and odour). This appendix ensures that the public water supply is controlled by legislation, and that it undergoes regular testing to prevent loss of quality during transmission and storage.

Any private water supply provided to a property must go through similar testing and is subject to similar requirements. As such, it can also be considered wholesome.

Within a property, water systems are subject to the Water Regulations, which ensures that the water does not become contaminated once it has left the mains supply.

What are the Water Regulations?

Once you have had water supplied to a property, it is covered under the Water Regulations. These by-laws set out a series of legal requirements for the design, installation, maintenance and operation of plumbing and drainage systems, water fittings and all appliances which use water in a home or business. The regulations also have an important role in safeguarding water supplies, protecting the health of the public and promoting efficient water usage. 

The by-laws apply to every type of property that has been supplied with water by its local water services, or is due to be supplied with water by them. They also apply from the point the water enters the property’s underground pipe (this is usually at the stop tap found at the boundary) and travels through to the drainage system, fittings and appliances.

The Water Regulations do not apply if a property’s water supply is private, and is never taken from local water companies. However, the regulations would apply if a property received a top-up supply from a local authority. The by-laws are also separately regulated by national parliaments, so each country within the UK will have its own guidelines for you to follow, depending on if you are in England, Scotland or Wales.

For More Information About Your Mains Water Supply

Responsibility for your mains water supply will normally fall to your local water authority, as it sits outside your property boundary. If there is ever any trouble with the pipe that serves your home or business, you’ll need to contact them in order to have it unblocked, repaired, or even replaced if the damage is too great for a simple fix. 

This may leave you wondering what to do if the problem is located within your property boundary, or if you don’t know where the issue is in the pipe system. However, there is no need to worry, because Coastal Drains is here to help. We pride ourselves on our expertise in all matters relating to your drainage system and we will be able to send out a fully trained and qualified engineer to inspect any issue, before they provide the solution that sees your drains flowing as they should.

We’re available to take any call or email 24 hours a day, 7 days a week, so there is never a bad time to contact us if you need us right away. Get in touch when you discover a problem with your drains and let us show you what we can do to get your property and your daily routine back to normal.