standing in the rain with your mouth open

is one way to drink rainwater.  Catching and filtering  it is another…

…first a disclaimer: I am no licensed plumber. He ran for the hills when we tried to hire him, so this is what I figured out on my own. I am not saying this is the best way, just what I did.

Drinking rainwater can make you pretty sick if you do it wrong, so do your homework…

Of course, groundwater can have all kinds of stuff in it, too, especially with groundwater drawdown.  That was the case here: the well water was brown, so they wanted the supply to run through the same filters. Normally you would tie in the main supply after the rainwater is filtered, as in the RMS schematic below.


Either way, filter and drink at your own risk.

Let’s start with the fun part, plumbing code!

A google search will get you excellent info from, TCEQ, CDC and other reputable sources. Just be sure to check with your local plumbing code regarding rainwater integration. If they aren’t any, and you can’t get a licensed plumber to do the job, which is what happened to us, the best we could do was exceed the current closest standards. (We also had a licensed plumber check over this setup, and approved.)

For potable plumbing, choices were copper, pex or CPVC. I used CPVC here.

I worked with CPVC before, had not yet worked with pex. (Since then, I converted the main lines under this cabin to pex and retrofitted my basement to heat my house with solar hot water, but that’s another post!)

Also notice the unions, and the handles mounted on the board. This is to have the option of removal since this cabin is not used in winter and the filter panel could then be easily removed and used in another location.

Originally I was going to buy a Water Organizing Module (W.O.M.) from, because they know what they are doing.

Problem was:

  • the size (I had a very small space to work with),
  • the price (about $3,000) and
  • it uses all regular PVC, or at least it looks like it.

I have a ton of respect for them, and I based this overall layout on this. Why? They use rainwater 4 times before letting it go down the drain. Get Mike’s book “Water from the Sky” and prepare to have your mind blown.

Oh yeah, rainwater harvesting just might be illegal where you live. If so, I didn’t see anything 😉 And we may have a storage solution for you.

More codes are being written and accepted for bringing rainwater into your home, because it’s kind of stupid not to. Besides the volumes of blah blah technical (but very important) data, a couple main requirements are: 1. a back flow preventer and 2. an air gap.

“…Although there are other ways to meet the requirement, most designs will:

    •   use a filter (usually a cartridge or membrane filter) that is capable of removing at least 99 percent of the particles that are 3.0 microns or larger in diameter;
    •   include a disinfection system (such as chlorine, ozone, or ultraviolet light) that is capable of inactivating (or killing) at least 99.99 percent of the viruses that might be present in the untreated water; and
    •   be large enough to treat an adequate quantity of water to meet your customers’ maximum daily demands at any time of the year.”- (from Texas Commission on Environmental Quality RG-445, Rainwater as Public Water Supply)

Whether you collect rainwater in rain benches, rain barrels, IBC totes or a garden shed, reducing runoff is only half the benefit. The fun part is using it.

Pressurized water from Rain Benches shooting all over

Pressurized unfiltered rainwater shooting all over

Most rainwater can be simply used for irrigation. Luckily, plants don’t care. They might even appreciate any added “fertilizer” in it.

But if rain or snow melt is your only supply, or if you want the option to have clean rainwater when your current water supply is interrupted, here are what I understand are the best ways to do it, from the simplest homemade DIY to the more commercial products on the market, not necessarily in that order..

The Perfect Water Filter

The best filters will recreate mother nature, which uses plants and earth.  Oh sure, we do our worst trying to add everything from pesticides to pharmaceuticals to arsenic from fracking, but water from a well that has been filtered through plant roots and soil “should” be safely drinkable.  Of course, in the event that it isn’t, it’s nice to have a backup.  (scroll down to #6 for one of the simplest – and still perfectly safe – DIY methods)
In any case, the best advice when starting off is to get your rainwater as clean as possible before it even gets to your drinking water reservoir. Ideally you will have separate water storage for irrigation and for drinking water, and here are the essentials:

1. Roof and Gutters

In a perfect world, you have the ideal roof for harvesting rain:  metal.

If you live in a perfect world, well congratulations! You get to happily skip on down to #2.

If, however, you are like me and 92.4% of homeowners out there, you have an asphalt shingle roof.AsphaltTea

The last thing you want to sip on after a hard day’s work is a tall glass of hot asphalt tea.

ShingleSaverTake heart, there’s still hope.

If you ever saw “The Garbage Warrior,” you know Mike Reynolds.   I asked Mike at a seminar, “What’s a guy to do with a shingle roof?” He said, “Coat it with acrylic.”  So that’s what we did.

Acrylic roof coating; lots of brands out there- I used a product on this roof called ShingleSaver.
  • You roll it on with a long paint roller and pans. (I am in no way affiliated with it, just used it that’s all)
  • It isn’t cheap, but it coats your shingles and keeps a large majority of those little crumbs and chemicals from running right straight into your drinking water, or on your veggie garden for that matter.
  • I found some for $27/gallon at a local hardware store, and here is a better deal (works out to $20/gallon) for a similar product: (disclaimer: I might make $0.37 or so if anyone buys this, but that’s only if I did it right…) Anvil ROOF-TEC Acrylic White Elastomeric Roof Coating 5 Gallon

Screen Shot 2016-04-07 at 1.48.03 PMA gutter guard and a diverter with a filter

would both be good moves to keep that incoming water as clean as possible as long as those filters are cleaned periodically. Even the self-cleaning ones should be checked. (ok I am totally affiliated with this lady who came up with the Saving Rain diverter. She’s my mom. She is also the greatest, and she’s legally blind from a condition called Blepharospasm. Help her out here!) diverter cost about $40

2. First Flush Filter

This is basically a leaky tank; it takes out the worst of the runoff, that first 10 or 20 gallons of rain that washes all the crap off your roof or gutters.  After it fills with swill, the clean(er) rainwater you want to keep is then redirected into the water storage device of your choice.

I used a series of 3 first flush filters, 1 from a kit (cost about $30) and 2 homemade using PVC, for this project.

After the rain is done, the first flush slowly “leaks” out and is ready to take the “first flush” out of the next rain.

3. Settling Tank for Irrigation

This can be a barrel, a tank, a rain bench, whatever, and if your first flush is adequate, it’s not absolutely necessary. In the picture below (source:, you see how the first tank has the most sediment.  That’s what you want..

Important notes on the above graphic: The incoming water comes in at the bottom, not falling in which would stir up all the sediment on the bottom every time it rains.

Also, all of these tanks feed to the same pump. If separated for use, the left would be better for irrigation and the last on the right will be the cleanest for drinking.
One best practice for drinking rainwater is using a floating suction filter to pull water from the middle of the tank, not from the surface and not from right off the bottom. The idea is that the cleanest water in any given tank is just below the surface.
Shown: WISY fine filter – cost about $190

4. Drinking Rainwater Tank

  • Food grade (FDA approved material), either glass (ideal, but not likely), stainless steel, fiberglass, coated concrete or plastic lined (most economical).
  • Not allow any sunlight to reach the water, as this will grow algae.
  • Disinfect it with a bleach solution periodically, for elimination or maintenance
  • Completely sealed so not to allow insects or pests to reach the water reservoir
Again, the cleaner the rainwater is before it enters, the less to filter coming out (hint: this lowers maintenance).

5. Final stage Drinking Filters and Pumps

courtesy of rainwater management services

A simple option is a gravity filter (see #6 next), but I needed to tie it into the supply because the well water is pretty unreliable.

The filters are pretty important to get right, so I leaned more toward over-filtering than under, with either a UV filter (if you use a pump for pressure and have ample power supply for the UV light), or a Doulton ceramic filter.  If you can use both, go for it. Better safe than sorry!

I have used both types on different projects, and I like the Doulton Rio 2000 6 candle ceramic – with a clear standard housing so you can see when it needs to be cleaned.  You can clean the candles over and over, which is nice. Just be careful. They will shatter if you drop them.

Here’s a link to the Doulton Rio 2000 6 candle:

I used this housing, too– I like to use clear so we can see when it needs cleaning):

And don’t forget to get the mounting bracket (not included) and bolts or screws to mount the filter to the bracket and bracket to the wall! (yes, I had to get some)

Here’s a link to the Sterilite 12v UV filter I first used:

or here is a 120V version:

This is where it gets tricky, because in order for the UV or ceramic filter to be super effective and last a long long time, you want to take as many particles as possible out of the water.  This can be done with replaceable 5 micron, then 1 micron or smaller sediment and carbon block 10″ filters (the standard size available), but I’d rather use a series of Rusco “spin down” mesh filters, which are easily cleanable and therefore do not require replacing any cartridges.  These are used in the Earthship system, from 500 to 1000 mesh (15 micron).

**Update: this filter panel was actually updated to switch the UV filter out with a ceramic filter, so no more draining the battery bank running the UV light!** see pic below…


NOTE: I have since replaced some of the CPVC with flexible tubing per the pump manufacturer – so everything doesn’t pick up its good vibrations..

Also, if you are off grid and using a UV filter, do this:

Put both the UV filter and the pump on a switch, so you do not have pressure, or water, unless you turn both on.
Yes, it is a hassle compared to just always having water pressure, but the alternative is you drain your power supply and then you have nothing!

And come on, you’re living off grid and you have filtered, pressurized, free drinking water. It’s not so bad to flip a switch.

Speaking of pressurized, if you’re looking for a good pump for constant water pressure, I have used a couple with success. The first, a Wayne 1/2hp transfer pump, is cast iron and is the longest running that I have installed, since 2009 and has weathered freezing every winter.
Link to this pump on Amazon:

The second is a Shurflo ‘Revolution’ pump, 12v – this is a standard RV pump and the one that I used on the island. (You can hear it running in the video above)

I haven’t had any problems other someone busted the pre-filter off with the threads so I had to replace it, but the price is right. Link to this pump on Amazon:SHURflo 4008-101-E65 3.0 Revolution Water Pump

Shurflo also makes a 115v pump, that I have not used yet but it looks like the folks over at Earthship Biotecture are currently using.  Those guys have been at this a long time, so I put a lot of stock in what they are doing.  I have met Michael Reynolds and read all of his books; the guy is absolutely brilliant.
Here is a link to that pump on Amazon:

One final note on disinfection and the recommendation of adding chlorine to maintain safe drinking, straight from TCEQ:

  • Ultraviolet light (UV) is extremely effective against Cryptosporidium, but high doses are required to inactivate some viral pathogens. In addition, UV systems do not maintain a disinfectant residual in your plumbing system.
  • Free chlorine is very effective against viruses but is virtually ineffective against Cryptosporidium. In addition, it is easy to maintain and measure a free chlorine residual in your plumbing system.

So if you want your rainwater to taste like city water supply, and more importantly to wipe out any viruses, here is a link to an LSU law site for adding chlorine to purify water:

That’s pretty much it, now don’t waste it, i.e. try not to water your lawn or plants with drinking water, or flushing the toilet for that matter.

…Sure, unless Scruffy drinks from the toilet on a regular basis, but Scruffy also drinks from mud puddles.  Even running wash water through a sand, gravel, or planted biofilter will clean it up immensely. But that’s another post…

What if it doesn’t rain?

Drink A/C condensate and make a solar still! And for Pete’s sake stop watering plants with drinking water. Use your wash water (grey water) instead – but that’s another topic…

For now, Google “Laundry to Landscape” and follow Art’s plans.  Genius.  Simple.

6.  And for simple DIY Drinking Water How-To… Look No Further

Straight out of one of the oldest homesteading books out there, this slow sand filter design is the basis of many commercial filters available now, and goes back to recreating nature, or at least trying..

There are many great how-to posts out there for simple filters, some using a cut off plastic bottle. Remember, generally the more filter media the better, and the time factor of developing the natural beneficial bacteria layer is important. Again you are trying to recreate the natural filtration of the ground, where the top layer with plants and living microorganisms (establish over time) greatly purify water as it filters down into the groundwater. For an in depth look at this biological filtration layer:

Along those lines, there is an even simpler way to disinfect water for drinking called the SODIS (“solar disinfection”) method.

It has been scientifically proven that if you sit a clear bottle of water in the sun for 6 hours, it’ll be drinkable.

Check it out here:

So… there’s my 6 cents!

I hope this helps a little to see what some guy did on an island (sorry no, not Gilligan). If you have any questions about how I did anything else in this system that I haven’t explained here, shoot me any questions over at our contact page here:  Hey, Scott!

Happy Rainwater Harvesting!

Peace, Love, Irrigation…


 (Editor’s note: This has been updated and added to the original post from April 16, 2015, in order to provide more complete information. Hope it helps!)