This is actually my second try at harvesting rain water.  The first time was at my previous property and it did not turn out so well for one main reason…

It is critical that you keep your tank completely sealed!


I made the mistake of cutting a hole through the tank lid so I could easily use a “calming” foot and fill the tank from the bottom.  No matter how hard I tried, I could never seal around the 3″ PVC going through that hole.

Always use threaded or glued fittings in your system and do everything you can to keep the water in the tank fresh.  That means away from sunlight.

If you look on the internet you will find all kinds of systems ranging from total off-grid harvesting to a rain barrel under a gutter downspout.  What I’m showing here is nothing special just what works for me.


One thing you need to know if you intend to drink rainwater is that a quality final filter is a must.  In a SHTF scenario I only trust Lifesaver products or boiling.

For everyday use I have a Travel Berkey to take that last bit of mineral taste out of our already excellent well water, but I would never fill a Berkey from our pond and drink from it with peace of mind like I would with the Lifesaver Jerry Can.

I’ve had the Berkey filters fail miserably (de-lamented) and the design allows for weep-by into the second chamber if not properly sealed which can be hard to assure as they are delicate.

Save up and get the Lifesaver Jerry Can, it’s worth the investment.  See my other post Got Water? for more details.


  1. Provide gardening water during normal times.
  2. Provide animal-potable water during SHTF for farm animals.
  3. Provide an alternate water source for whole house when well is down.  System needs to be pressurized (via 12vdc RV Pump) but not potable, just clean enough to take showers and flush toilets to septic.
  4. Provide a pre-filter for human-potable water using the Lifesaver Jerry Can as the final stage in the house.

Lookup how to size your first flush correctly for roof surface area.  Mine is a bit small for this roof having been sized for a previous one.  Someday I might add another or larger chamber, but for now I just let the system run with the spin-down dump valve open to clean it up before water sending through the filter into the tank.


  1. A tin roof (3-tab is a no-go!),
  2. Leaf eater, not needed here but was at last location.  $28.99
  3. First Flush Diverter section.  $29.99
  4. Rusco 1-1/2-250-F Polyester Screened Spin-Down Filter System  $76.82
  5. Rusco Sun Shield- Spin Down 1.5″ & Sediment Trapper 1.5″ SS1.5  $16.66
  6. 1″ pool chlorine tabs for pre-treatment and storage longevity.  $28.46
  7. 1100gal tank.  $500 on sale at Coastal
  8. Skimmer intake float (cleanest water is 4″ below surface).  $159.99
  9. Overflow trap kit that returns water to drain if tank is full, also keeps bugs, mice, etc. out when not full.  $147.95  (My first setup used the calming inlet in this kit, I chose to skip it this time around.)


The key is to get your water stored in the cleanest condition you can from the start.  The crazy cost of the floating intake setup blew me away, but it’s a critical part of the system IMO and it’s worth doing it right.

The trap overflow allows the tank to be sealed against spiders and other crawlies that might walk up your overflow pipe, but your need to be sure water is inside this even during the dry months or you will have spiders, etc. in the tank.  You need to put some screen mesh over the exit of the overflow pipe (as well as the tank lid breather) to prevent amphibians from climbing in.

The first day of rain I opened the lid of the tank to find a small frog inside.  I had already sealed the lid breather port with mesh, so his only point of entry was the overflow pipe.  He obviously was not deterred by the water trap.  Lucky for me, he decided to sit nicely by the lid and let me pull him out without fuss. 🙂

Adding a piece of plastic screen door material between fittings should prevent this from happening again.


20181005_101425The spin-down filter is new to this system and I now consider it mandatory IMO, even with the first flush, it captures a lot of junk.  It also allows you to put a 1″ chlorine tablet in the bottom which will sterilize the water as it flows through, making the rain water more suitable to drink for farm animals without further filtration.

The chlorine is not mandatory, but as long as I have it I will use it.

Don’t cheap out!  Buy a real water tank of > 1000 gal, not a 250 gal tote that had soda syrup (sure it wasn’t silicon?), etc, in it.  I worked at a plant that sold their silicon totes for $5.00 to employees, one of them sold them for water tanks and said they were “food grade” so buyer beware!

Paint your PVC (especially valve handles) for extra UV protection.  If you get a spin-down, buy the neoprene cover or put a sock on it for the same reason.

20181006_0920071You might consider leaving some PVC fittings (on the un-pressured side) unglued so you can take it apart without cutting it up if can ever see a need to move.

On the first flush unit, I made the mistake of gluing into the factory “Tee”,  which is a specialty item.  I was lucky and had just enough to cut and glue the 3″ to 1.5″ reducer on one time.  The 1.5″ coming out of it is not glued this time, leaving options for a future expansion of relocation.

Clean the system after each rain!

20181006_093429I learned the hard way to add a screen to catch the float ball and inline filter of the “first flush” tube.

First time I cleaned it the ball rolled out and went straight into the hole and 5-8 ft down the drain out of sight.

A wet vac saved the day on that one.

That’s the system in a nutshell, nothing too elaborate but it works for me.  Hope you have gotten some ideas from the post and good luck with your own system.

Feel free to link to yours or add comments, suggestions below.

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