Turning Rainwater Into Drinking Water: 3 Ways To Do It

There’s nothing better for an off-grid homesteader than knowing that they can have all the water they could ever want just by installing a few water tanks to harvest the rain.  The only problem is, can rainwater be filtered for drinking?

Rainwater can be filtered for drinking as long as you have a clean catchment surface and you use a proper filter.  Water for the whole house can be filtered using a uv filter or quantum filtration system or you can use a gravity filter such as a Berkey Water Filter just for your drinking water.

If you are interested in converting your harvested rainwater into something drinkable, this article will dive deeper into all that you need to know on how to do it.  I felt a true sense of freedom when I finally put in filters to make my water drinkable.  I have all that I could ever want and no one else can touch it.

Clean Water Begins With Best Practices

A lot goes into a typical water system to ensure that the water is clean and safe to drink.  You are the water company now and that burden lays with you.  It is best that you make sure that every part of your system is as clean as possible and constructed with the proper materials.

A filter only goes so far.  If the water you are starting off with is green and filled with debris, you are going to have a tough time turning it into drinking water.  It’s important to make sure you have a clean catchment surface and some pre filters along the way.

Best Roof Material for Rainwater Collection

There are many ways to build a roof, with asphalt shingles, terracotta tiles, thatch, but none of those are suited for being used to harvest rainwater.  All of them leach either chemicals or natural tannins that make the water almost impossible to filter efficiently.

Pre-painted, corrugated metal roofing is the only roofing found to be clean enough to harvest rainwater for drinking.  It offers up the cleanest catchment surface possible, with little to no leaching as long as the roofing is kept in good shape.

Pairing the roofing with a galvanized steel seamless gutter will help you go even further in ensuring pristine water in your catchment tank.  Seamless gutters make it possible for the water to travel freely out of the gutters and into the downspouts without any “dams” in between.

Plastic gutters from home depot are OK, but the do use a raised coupling to connect different gutter sections and it is there that debris, algae and pathogens tend to collect.  Sure enough after the next rainfall, they’ll all end up in your water tank.

To keep the roof and gutter material in good shape for continual clean water harvesting, it is advisable to pressure wash and clean out the gutters every 6 months.  Before washing down the roof, make sure you disconnect the downspouts so all of that debris doesn’t end up in the tank.

3 Way To Make Rainwater Drinkable x
3 Way To Make Rainwater Drinkable

Leaf Guards and Prefilters

Before the rainwater from the roof even gets into your water tank, you should have a couple of pre filters installed.  I like to use a leaf guard and panty hose or paint strainer.  These prefilters serve as an additional measure towards ensuring that only clean, debris free water enters the tank.

A leaf guard is a device that is installed on each downspout of the gutter system.  Essentially, it is a slanted screen that diverts large debris out of the downspout but still lets clean water continue through.  The leaf guard acts like a course filter.

Right wear the inlet pipe lets out into the water tank, I like to install panty hose over the pipe end.  This panty hose catches even finer debris that the leaf guard missed.  It is surprisingly good at its job.  All I have to do is replace it every month and it is able to do its job.

Best Tank Types To Store Water For Drinking

Almost any water tank will do for harvesting rainwater.  All throughout East Hawai’i where rainwater catchment is common practice, most people use a tank with a vinyl liner.  These tanks are able to store very clean water, but there is some worry of leaching from the vinyl in some circles.

The best tank to store water would be a galvanized water tank.  Galvanized metal has been tested to be very safe when it comes to the possibility of contamination through leaching.  However, these tend to be very expensive.  There are tradeoffs with anything.

Any water tank is better than no water tank, just make sure that it is fully enclosed or covered in some way.  We still have a few filters for the water to run through before it reaches our water glass.

Related: Does A Rainwater Tank Need A Pump?

3 Different Ways To Filter Rainwater For Drinking

Filtering your rainwater into drinking water has never been easier.  There are many systems out there that do a fantastic job for very little price.  It was a game changer when we finally got one of our own.  No more trips to the county water spigots filling up 5 gallon bottles.  Drinking water now flows right out of the tap.

UV Filtration Systems

A UV Filtration System treats unsafe water containing pathogens and bacteria with a germicidal ultraviolet light.  The UV wavelength scrambles the DNA of the live organisms, making them unable to reproduce and cause you to be ill.

A UV Filtration system can be used to treat the water of an entire house.  It does not filter out coarse debris, prefilters are necessary for that, but it does a great job at killing pathogens.

It utilizes a ballast that acts as the power control center and a specialized UV bulb inside of a housing.  The prefiltered water is exposed to the light, killing off any pathogens and then continues on to the home.

The drawbacks of this system is that it does take power to operate, making it a little more challenging for those 100% on solar.  It is also necessary to change an expensive light bulb every year.  

Quantum Filtration

This is what I have on my house and I have to say, I am a fan.  After one year of using this filter to turn our rainwater into drinking water, I am happy to say no one has gotten sick.  We have even had it tested on numerous occasions and it comes out with passing marks every time.

The Pulsar Quantum Water Filter developed by US Water Systems utilizes an advanced technology using a positively charged surface on the filter media that attracts the electrons in the pathogens, which are destroyed when they come in contact with the dynamic Activated Silica ceramic surface.  Death on a quantum level.

These filters are very easy to install with some basic plumbing knowledge and require no electricity to operate, making them perfect for the off grid homesteader.

Before these filters came along, I never thought I’d be able to filter my rainwater into drinking water.  I’ll tell you, it sure is nice not having to worry about accidentally drinking the water while taking a shower. 

Be sure to check out this filtration system for your drinking water needs.

Quantum Disinfection vs. UV Disinfection

Instantly Kills 99.99% of bacteria
Adds nothing to the waterAdds nothing to the water
No power needed
No chemicals addedNo chemicals added
Disinfects 24/7/365
Low Maintenance

Related: Clarify Quantum Disinfection: Turn Rainwater Into Drinking Water

Passive Gravity Fed Filters

For those of you looking for a simple, plug and play solution that takes no skills what so ever, there is still hope for you.  There are several passive gravity fed filters that work much like your home Brita water system that you may already be familiar with.  

Just pour the water in the top and let it filter down.

The best name brand in this market is the Berkey Water Filter.  These filters are able to eliminate 99.99% of any harmful bacteria that may be in the water as well as particulates.  They are easy to setup and require no power to operate.

There are some downsides to this system though.  You have to regularly fill them with water that needs to get filtered.  This can be difficult because they are designed to be paced on the countertop, which can make the top of the unit so high that you would need a stool to reach the top.

It is also hard to know when to refill them due to their height.  It is also unclear how often you need to change the filters.  For the price, I’d choose to go with the Pulsar Quantum Disinfection and just treat the whole house.

Keeping Water Fresh During Dry Periods

There are times when it doesn’t rain for long periods of time.  If water is left sitting for too long with out being replaced, it can become stagnant and smelly leading to some foul tasting water.  These problems are simple to over come using one of the 2 methods mentioned below.

Chemical Treatment

One simple option to treat water that has to sit for too long is to add some bleach 1x per month.  Bleach keeps the water free from algae, mosquito larvae and other pathogens and just keeps it clear over all.

Since we have filters installed to filter our rainwater to drinking water, adding bleach is considered safe because it is commonly filtered out along with any bacteria during the filtration process.

All it takes is a cup full of bleach for every 2000 gallons of water or so and your water should stay safe through the longest of droughts.

Related: Keeping Water Clean In A Rain Barrel: The Essential Guide


If you are not comfortable with adding chemicals into your drinking water to keep it fresh, you could try using some form of aeration.

Aeration helps oxygenate the water and keep it moving, lessening the stagnant, smelly water that is common when it sits for a longer period of time.  It may not help with eliminating mosquito larvae or bacteria from forming.  Bleach really is the best for that.

Hopefully the rains don’t hold off for too long though.  It’s always nice to get fresh rainwater in there for your drinking water needs.

However you decide to filter your rainwater, I hope I was able to help answer some questions that you may have.  If you have more, feel free to drop me a line at anytime.  I’d love to help you out any way I can.  

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Sean Jennings

Sean has been living simply Off-Grid in Hawai'i for over 18 years. He lives debt free on Hawai'i Island with his family and over 40 chickens. When he's not tinkering around the homestead, he's off exploring the shorelines for fish & surf.

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