Folks living off grid should definitely be collecting rainwater. Even if you live in dry climates, harvesting rainwater should be done.  Rainwater can be used for a multitude of things: the garden, livestock, flushing the toilet, and more.

However, untreated and unfiltered rainwater should not be used for drinking because it has contaminants in it. But is it possible to boil rainwater to make it safe to drink?

Boiling rainwater is not sufficient by itself to make rainwater safe for drinking. Boiling only kills disease and germs present in the water, it will not remove chemicals or dust particles, which are possible because of environmental pollution or residue on the roof. You will need further filtration in order to make your collected rainwater safe for drinking.

In an emergency situation, boiling water can be sufficient for short periods of time, but prolonged ingestion of boiled water without further filtration can be harmful. Letʻs read on to find out why.

Related: Why take the time and energy to boil water when you can just run it thru a water filter, like a Berkey Water Filter. The Berkey is what all other filters are compared to, so why not get the real thing. Equipped to filter rainwater without the need to boil, it is a great way to ensure clean drinking water at home.

Berkey Water Filter

Why Is Boiling Rainwater Not Enough?

Think, just for a moment about how you collect your rainwater – you probably direct it off your roof, right? The same roof where birds can leave droppings, dust accumulates and smoke or other environmental pollutants can easily collect. 

Sure, boiling water can kill the bacteria present in the bird poop, but it cannot remove the dust or residue from smoke or chemicals your neighbor sprayed on their field. 

If you use another type of rainwater collection, like a rain barrel funnel, remember that rain, although it is natural, is not ‘pure’. The water cycle of precipitation, evaporation, and condensation sucks up pollutants in the air, and the droplets of water that make up rain may carry particles of pesticides, dust, smoke and more. 

A recent study just released by a team of researchers at Stockholm University and ETH Zurich found that rainwater is unsafe to drink globally because of “forever” chemicals in the water.

Boiling your water will not eliminate these contaminants.

Just because the water looks clean and is safe for washing laundry or flushing your toilet does not mean that it is safe for you to put directly into your body. That’s why the rainwater you collect should not just be boiled to remove germs parasites, but treated and filtered, too.

Learn more about how we make our rainwater drinkable by checking out this post.

What Contaminates Rainwater?

Germs and Parasites

There are any number of diseases you can get from drinking untreated rainwater:

  • Amoebas, parasites and protozoans 
  • E Coli, salmonella 
  • Giardia
  • Bacterial pneumonia (legionella)
  • And Clostridium which can lead to botulism.

This is not an exhaustive list, but have I scared you enough, yet?

The good news, however, is that these diseases and parasites can be destroyed through boiling. This is where boiling rainwater might actually make a difference. But, keep reading to learn why there is more you need to do before drinking your collected rainwater.

Toxins and Chemicals

Industrial-strength chemicals and man-made gasses or powders, like fire-retardants (especially if you live in California or Texas and have had to recently battle wildfires), remain in the atmosphere and can incorporate with rain. 

They don’t easily go away, that’s why these substances (known as poly-fluoroalkyl substances) have been nicknamed “forever chemicals”.

You don’t want to drink this stuff, and no amount of boiling will remove it from your water, either.

The good news is there are some methods that do remove these nasty chemicals from water: filters that use activated carbon and ion exchange, or a reverse osmosis system.

My Favorite Water Filter For Chemicals

To ensure your water is free from chemicals, there is nothing better than running it through a Berkey Water Purifier before drinking it.

The Berkey passes all the tests, proven to remove heavy metals, chlorine, poly-fluoroalkyl substances and more! 

My family used one for years before upgrading to a fancier whole house filter.  The Berkey lives up to its reputation, they really are a great way to ensure you and your family clean drinking water.

Debris and dirt

Finally, debris and dirt can enter your rainwater simply from running over your dusty roof before it hits your catchment system. You might have dead leaves or other natural debris in your gutters, too.

Here is where a ‘first flush’ diversion system and a filter really help.

Even if you never intend to drink your rainwater, you should still utilize a first flush system because it ensures that the water reaching your collection system is cleaner, overall.

The first wash of rain off your roof is going to catch all the dust, pollen, bits of leaves and dead bugs off your roof. You do not want this in your rain barrels, so make sure you flush it away and start collecting water in your catchment system after this is diverted.

What Else You Can Do To Ensure Clean Water

Make sure your roof is made out of appropriate materials (a galvanized metal roof is ideal for rainwater collection, whereas a zinc roof, or a shingle asphalt roof is not recommended).

Use filters on your gutters to prevent debris or small critters from entering your water.

Regularly check and maintain the pipes and lines utilized for your rainwater collection system to ensure there are no vulnerable places where contaminants might enter.

Set up a first-flush system to divert that initial wash of water off your roof and collect the consecutive, cleaner rainwater that follows after.

Even if you won’t be using your rainwater for domestic purposes, you should still treat your rainwater to prevent bacterial growth. Treat your water with chlorine, iodine or a carbon filter. You could also use a UV light to clean your rainwater.

And, I cannot emphasize this enough: store your rainwater in appropriate containers.  You can take every precaution to treat and decontaminate your rainwater, but if you don’t store it in the right container with the appropriate materials, it will all be wasted.

You want containers made out of concrete, galvanized steel, fiberglass or high-quality plastic for your water tank.

Learn how to set your system up right, check out this post that goes into detail on how to set up your own rainwater harvesting system.

Final Thoughts

Boiling rainwater is not enough to make it safe to drink. Boiling only kills germs and pathogens present in your water, it cannot address chemicals. 

You need to filter and treat your rainwater, with either reverse osmosis, a UV light, chlorine, activated carbon or a mix of these treatments in order to make your rainwater safe for consumption.