Collecting rainwater is one of the simplest steps towards water resilience, and in the UK it is generally allowed. Short answer: you do not normally need a licence to collect rain from your own roof for your own use. Whether that water is safe to drink is a separate matter.
Do you need a licence?
The Environment Agency has said it does not regulate harvested rainwater as long as its use does not harm the environment. Water abstraction licences are about taking water from rivers, streams and groundwater, not roof runoff caught in a tank. Keep rainwater separate from other sources, and do not let overflow cause pollution or flooding.
What are the rules for plumbing?
- If you connect a rainwater system to a home that also has mains water, water fittings regulations apply to prevent backflow into the mains. Your water company and a qualified plumber can explain what is needed.
- Non-drinking rainwater pipework should be kept fully separate from drinking-water pipework and clearly marked.
- Storage tanks need covers, screens against animals and insects, and a safe overflow.
Can you drink rainwater?
Roof-collected rainwater can carry bird droppings, leaf matter and contaminants, so drinking it normally needs filtration and disinfection (for example an appropriate filter followed by UV treatment), regular maintenance and testing. Private drinking water supplies in England are regulated, with local authorities responsible for risk assessment and sampling for many supplies. Read off-grid drinking water and private supplies.
How much water can you collect?
Litres per year ≈ annual rainfall (mm) × roof area (m²) × collection efficiency
Example (illustrative only): 100 m² of roof, 700 mm of rainfall and a 0.8 runoff factor gives about 56,000 litres a year, or roughly 150 litres a day on average. But annual totals hide the real problem: dry spells. Tank size depends on your daily demand, how long a dry period you must cover and your backup supply.
Sizing the tank
- Estimate daily demand by use: drinking and cooking, washing, toilet flushing, laundry, animals and garden.
- Choose how many dry days you want to cover.
- Multiply demand by dry days, then compare to what your roof can realistically collect.
- Add a backup: a mains connection, a delivery arrangement or a borehole.
Our Water Resilience Planner models demand, collection and storage autonomy in one workbook, and keeps water quantity separate from drinking-water safety.
What does it cost?
Costs depend on tank size, whether it is above or below ground, filtration and pumps, and whether you plumb it into the house. Get quotes rather than trusting one number. The Budget & Cost Planner helps you compare options.
FAQ
Is it legal to collect rainwater in the UK? Generally yes, for your own use from your roof.
Is a water butt enough? A butt is useful for gardens; it is not a household water supply.
Do I need planning permission for a rainwater tank? Small tanks often do not, larger installations or buried tanks may; check locally.
Sources
- Drinking Water Inspectorate: private water supplies, roles and responsibilities
- The Private Water Supplies (England) Regulations 2016
- Environment Agency
Educational information, not plumbing, health or legal advice. Rules differ across the UK; check with your local authority and a qualified professional. Last checked: September 2026.
