Can You Drink Rainwater? Is It Safe? What UK Households Should Know

May 30

4 min read

Updated: 2 days ago

Last reviewed: September 2026

Quick answer Can you drink rainwater, and is it safe? Not without treatment. Rain falling through clean air is fairly pure, but by the time it has run off a roof, through gutters and into a butt or tank, it can carry bird and animal droppings, bacteria, leaves, dust and metals. A 2022 study from Stockholm University also found that rainwater almost everywhere on Earth contains PFAS ("forever chemicals") above some drinking-water guideline levels. Harvested rainwater is excellent for gardens and toilets. Drinking it safely needs filtration, disinfection and regular testing — and it then counts as a private water supply.

Using harvested rainwater? A bacteria screen can flag whether droppings or other contamination are getting into your tank.

Get the E. coli Test

Is rainwater safe to drink? Where the contamination comes from

Stage	What can get in
The air	Dust, pollen, pollution, PFAS
The roof	Bird and animal droppings, moss, leaves, and whatever the roof is made of (older roofs and flashings can shed metals)
Gutters and downpipes	Rotting leaves, sediment, insects, dead animals
The water butt or tank	Algae and bacteria (especially in warm weather), mosquito larvae, sediment

Droppings are the most important item on that list. Food Standards Scotland lists "insects, bird droppings, and dust" among rooftop contaminants, and cites a Canadian study that "found total coliforms in 31% and faecal coliforms in 13% of 360 rainwater storage samples".

What about "forever chemicals" in rain?

In a study published in August 2022 in Environmental Science & Technology, researchers at Stockholm University led by Professor Ian Cousins compiled rainwater measurements from around the world since 2010. They found PFAS in rain even in Antarctica and on the Tibetan plateau, at levels above the then-new, much stricter US EPA health advisories for drinking water.

What that means in practice:

It doesn't mean touching rain is dangerous.
It does mean rainwater isn't the "pure" water people assume.
Harvested rainwater doesn't get the treatment mains water does. For public supplies, the Drinking Water Inspectorate says water companies take "specific actions such as additional treatment and/or blending with other sources to reduce PFAS prior to supply". If you plan to drink rainwater, get specialist advice on PFAS treatment.

For how UK tap water compares, see Is UK Tap Water Safe to Drink?, which covers the 2026 PFAS data.

Good uses for harvested rainwater

Rainwater harvesting makes a lot of sense in the UK, especially with hosepipe bans in dry summers (nine water companies had bans in August 2026). Safe, sensible uses:

watering gardens and vegetable beds (water the soil rather than the leaves of crops you'll eat raw),
flushing toilets,
washing cars and outdoor areas,
in some systems, washing machines.

Label any rainwater tap clearly as not for drinking, and keep rainwater pipes completely separate from mains pipes — they must never be connected.

How to make rainwater safe to drink

Some off-grid homes do use rainwater for drinking. If you're considering it, treat it as a serious private water supply:

Collect well: a clean roof, fine gutter guards, and a "first-flush" diverter that throws away the dirtiest first part of each rainfall.
Store well: a sealed, opaque tank with a tight lid and screened vents.
Treat it: sediment filtration, then disinfection (usually UV), plus carbon or other specialist treatment for chemicals.
Test it: a full laboratory analysis before use, then regular bacteria tests — see E. coli or Coliforms in Your Water Test?
Involve the council: as a drinking water source, it falls under private water supply rules. See Private Water Supply Maintenance.

In an emergency or when camping

If rainwater is the only water available:

collect it directly in a clean container, not from a roof or gutter,
let any sediment settle, then pour off the clear water,
bring it to a full rolling boil and let it cool.

Boiling kills germs: the DWI says it means "any bacteria or viruses that were in your water are killed or deactivated". It won't deal with chemicals such as nitrate: North Norfolk council notes that "Boiling the tap water will not reduce nitrate levels."

Test your water

If rainwater is part of your household supply, test it regularly.

E. coli Test

Complete Drinking Water Test Kit

SustainWater home tests are screening tools. If a result is unexpected, or a health, legal or money decision depends on it, confirm it with an accredited laboratory.

Frequently asked questions

Is rainwater clean? Is it cleaner than tap water? Not by drinking-water standards. Rain picks up dust, pollution and PFAS on the way down, and roofs and gutters add more. UK mains water is treated and tested to strict standards; rainwater collected from a roof has had neither.

Can I drink water from my water butt? No. Water butts are fine for the garden, but the water sits warm and uncovered and picks up droppings and debris from the roof.

Can I give rainwater to pets or chickens? Many people do, but the same contamination risks apply. Fresh, clean water is safest.

Does boiling rainwater make it safe? Boiling kills bacteria and parasites, but it doesn't remove PFAS, metals or other chemicals.

Can I test my rainwater? Yes. A bacteria test can flag whether droppings or other contamination are getting in; a lab analysis gives the full picture. See How to Test Water Quality at Home.