Water Efficiency and Reuse
Rainwater, Maintenance and Environmental Protection · Plumbing
Saving water starts with the fittings and leaks already in a home and goes as far as reusing rain and bath water. This topic covers both, and the safeguards reuse needs.
Flushing and washing take most of a home's water. Dual-flush WCs, aerated taps and flow-limited showers cut use, and a water meter that moves while nothing runs is a quick sign of a leak.
In England, new homes are designed to a figure of 125 litres per person per day, or 110 litres where a planning condition sets it; Wales designs new homes to 110 litres. The figure comes from the fittings chosen, not from how residents behave.
Harvested rainwater and greywater are not drinking water. In England and Wales the water undertaker is told before a reuse system is installed, the mains top-up is protected by an air gap, and the pipework is marked so nobody joins it to the drinking supply.
Save first, then reuse safely
Updated
How to reason about the system
Fix leaks and choose efficient fittings before reaching for reuse. Where rainwater or greywater is reused, treat it as a separate, non-drinking supply: a protected mains top-up, marked pipework and no link to the drinking water.
Questions to take further
- Do I need permission for rainwater harvesting?
- In England and Wales the water undertaker is given notice before a harvesting system is installed, and it can attach conditions. A water butt filled from a downpipe and emptied by hand is not connected to the plumbing, so it needs no notice.
Sources
- GOV.UK: Approved Document G (water efficiency) — Guidance for England on the water efficiency figure for new dwellings and the two ways of showing it is met; guidance is not itself the legislation.
- Water Regs UK: notification — When the water undertaker must be told before plumbing work, including a new rainwater harvesting system, and how consent works.
- Water Regs UK: backflow protection — Contamination risks and why protection must match the fluid category and conditions.
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Lessons on the plumbing path
- Using less water
- Water efficiency in new homes
- Rainwater harvesting
- Greywater and marking supplies
Terms to know
Before you start: some plumbing work is regulated or notifiable
Some water fittings work needs notice to, and consent from, the water supplier before it starts. Check the rules where you live.
Gas work is for competent workers covered by a Gas Safe registered business in Great Britain. Northern Ireland has separate gas regulations. Do not work on gas pipes or appliances yourself.
In England, installing an unvented hot-water system over 15 litres is notifiable building work: use a competent installer registered with a competent-person scheme, or tell building control before work starts. Leave this work to a suitably skilled person.
Wales, Scotland and Northern Ireland have their own water and building rules; check which apply before work starts. Electrical connections belong with an electrician.
This guide does not qualify you or make you competent, approved or registered for plumbing, gas or unvented work.