Can you drink rainwater? What's in it, and what it takes to drink it

By The Downspout · Posted Nov 11, 2026 · 5 min read

Not without treatment. Rain picks up dust and chemicals in the air, then bird droppings, germs and metals from your roof and barrel. Boiling kills the germs but doesn't remove chemicals. Drink tap or bottled water, give rainwater to flowers and trees, and in an emergency boil or disinfect it first.

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Rain starts out fairly clean.^[1] The trouble is the trip: through the air, across your roof and into a barrel. Here is what each step adds.

Is rain clean when it falls?

Not quite. On the way down, rain picks up dust, smoke and other particles in the air.^[2]

It also picks up PFAS, a family of chemicals that barely break down, often called forever chemicals. A 2022 review of rain samples from around the world found one of them, PFOA, above a strict US health advisory everywhere it was measured. Even rain on the Tibetan Plateau, far from cities, carried about 14 times the advisory level.^[3]

That 2022 advisory was very strict. The limit EPA later set for water systems is 1,000 times higher: 4 parts per trillion.^[3]^[4] Even so, the Tibetan rain, the lowest reading in the review, was well under that limit.

Our take: PFAS in rain is a real warning about how far these chemicals have spread. But for a glass of water from your barrel, the bigger risk is closer to home: your roof.

What do your roof and barrel add?

Whatever sits on it. Bird droppings, dirt and germs wash into the gutters with the rain, most of all when it rains after several dry days.^[2] Roofing, gutters, pipes and tanks can add metals such as lead and copper.^[2]

When researchers tested 38 rain barrels around Philadelphia, more than 60% of samples held bacteria that signal animal or human waste. Lead turned up in almost 9 of every 10 barrels, at levels the researchers judged low risk for gardening.^[5]

The roof material matters too. Rain off wood, asphalt and tar shingle roofs may only be fit for watering plants, according to Virginia Tech's extension service.^[1]

Then the barrel adds its own. Sludge settles on the bottom, germs can live in the stored water, and mosquitoes breed in it if the openings aren't screened.^[6]

Steep asphalt shingle roof ridge with inspection steps looking over trees and neighboring yards under a blue sky. — An asphalt shingle roof. Whatever lands up here washes into the gutters with the next rain.

Does boiling make rainwater drinkable?

It kills bacteria, viruses and parasites. It does not remove metals or most other chemicals.^[7] If you need to boil rainwater:

Let cloudy water settle, then pour it through a clean cloth, paper towel or coffee filter.^[7]
Bring it to a rolling boil for at least 1 minute, longer at high elevations.^[7]
Let it cool, then store it in a clean container with a cover.^[7]

No way to boil? Regular unscented bleach kills germs too. The drops per gallon are in our emergency water guide.

Can a filter make it drinkable?

Not one filter alone. Homes that drink rain use a chain of steps, each for a different problem.^[1]

Screens and a first flush diverter. The diverter sends the first, dirtiest roof water away before it reaches the tank.^[1]^[2]
Fine filters that catch dust too small to see. A common setup is a 5 micron filter, then a 3 micron carbon filter.^[1] A micron is a thousandth of a millimeter.
Disinfection with UV light, ozone or chlorine, to kill germs. Chlorine alone does not kill the parasites Giardia and Cryptosporidium, so these systems add a 1 micron filter.^[1]
Regular lab tests for germs and chemicals. Your health department can tell you which ones.^[2]

Don't some people drink it every day?

Yes. Bermuda and the US Virgin Islands require new buildings to supply their own water, and rain is used for drinking there.^[1] In Australia, New South Wales Health says a well-kept tank can give good drinking water, and that clear rainwater with little taste or smell is probably safe for most people. It also says people with weak immune systems should ask their doctor first. Even so, NSW Health tells people in towns and cities to drink tap water, which is usually filtered and disinfected.^[6]

US health officials are more cautious. CDC says to use tap or bottled water for drinking, cooking, brushing teeth, rinsing produce and even watering plants you plan to eat.^[2]

Our take: if you have tap water, drink it, and give the rain to your flowers and trees. If rain has to be your supply, build it as a drinking water system, with treatment, testing and the permits your area requires.

What about in an emergency?

Rain is one of the sources CDC says can be made drinkable in an emergency, by treating it to kill germs.^[8] Boil or disinfect it first, as above. Skip any water that may hold fuel or other toxic chemicals. Treatment can't fix that.^[8]

Keep rainwater out of your stored drinking water. Mixing it in can contaminate the clean water.^[2] Water you stored ahead of time, or bottled water, is the better choice.^[7]

Wherever you live, your health department can tell you which tests and local rules apply to drinking rainwater.^[2]

In Sonoma County

In California, a drinking water rain system needs a permit. The state plumbing code has also said it can't connect directly to city or well water, and its filters must be certified to a standard called NSF/ANSI 53.^[9] For permit details, see are rain barrels legal in California?
Test at a certified lab. Sonoma County Environmental Health lists state-certified labs in and near the county. Ask staff which tests fit rainwater: (707) 565-6565.^[10]
Other water at home: see is your Sonoma County water safe to drink.

What it means for you

Store drinking water now, so rain is your backup, not your plan. Start with how to store water for an emergency.
Got a barrel already? Here is what to do with it this winter.

Photos by Devan Hemmings unless noted.

Sources

Checked 2026-11-11. Rules and programs change. If something here is out of date, the source above wins. Spot an error? See our corrections policy.