How I Built A Stand-Alone Rainwater Catchment System

Hans Quistorff wrote:Face the high side toward the sun and inclose it with clear roofing and you also have a greenhouse to start plants in in the spring.

Corey Schmidt wrote:i often use these equations to calculate catchment:

Corey Schmidt wrote:Looks great! Is it that you made watertight connections from the 3" pvc to the tanks so the water can back up and flow to the next one?
what is the general location of this project?

Sarah Gabriel wrote:great design! thanks for sharing. have you installed a sand filter or first flush diverter?

Wayne Conrad wrote:From my experience, I would suggest placing the water tanks underneath the shed roof. When placed in the sun, the water stored will very rapidly grow algie which will turn it green and cause an odor. I paint the outside of mine to block sunlight, however it still happens. I am in the southern USA, so we do have summer temperatures in the upper 90's regularly.
I have two tanks that are under a roof cover, plus are painted, and I still have to treat them with a small amount of bleach from time to time to kill the algie under control.  

Rudy Valvano wrote:

Corey Schmidt wrote:i often use these equations to calculate catchment:


Nice. I was wondering that from the other side of the equation. Please check my math but it needs 10 inches of rain to fill those 3 tanks.

Good for isolated areas with regular rain or expensive municipal water. Of course that depends on water usage and cost over the life of the structure.


I'm still not sure how to post with quotes. I'll get it some day.

We already have one container almost full in just a few days! This isn't an isolated area, but nobody actually lives on this farm so municipal water wasn't available as an option, unless we used our neighbor's water :/

miles rose wrote:
We already have one container almost full in just a few days! This isn't an isolated area, but nobody actually lives on this farm so municipal water wasn't available as an option, unless we used our neighbor's water :/

Dan Robinson wrote:How do you handle overflow when there's lots of rain and the tanks are all full?

Rudy Valvano wrote:

miles rose wrote:
We already have one container almost full in just a few days! This isn't an isolated area, but nobody actually lives on this farm so municipal water wasn't available as an option, unless we used our neighbor's water :/

That's good news. I learn a lot from results like this.
I should have said "Stand-Alone" instead of "Isolated". Hope I didn't come across as too negative.

Vincent Shelberry wrote:Man your's is nice. I want to grow watermelons and need more water, so may build one just like it!

If you're real, REAL cheap like me, you build it out of pallets
I did buy some wood for the top, but a little curb shopping in suburbia could have also yielded some free lumber to use for the roof, I'm sure.
I converted the inside of mine to a shed to store gardening tools resources...but I'm really liking the greenhouse idea too.

Olga Booker wrote:This is a great design, I like it a lot.  As for the algae mentioned above, maybe growing a climbing plant or two over the containers might do the trick?   It did work well for us, we have covered ours with a kiwi plant, makes great shade in the summer and in the winter, when the leaves fall off, it is no longer an issue, the winter sun does not provide that much heat.  Anyway, it was just an idea. By the way, last year, we did manage to harvest 20kg of kiwis from that plant alone!

Wayne Conrad wrote: I have two tanks that are under a roof cover, plus are painted, and I still have to treat them with a small amount of bleach from time to time to kill the algie under control.  

Gary Lee wrote:Here's one I built two years ago to irrigate garden and a few small fruit trees. Algae is starting to build up on the inside of the tanks so I do need to clear that and paint the tanks. Basically I catch rain off 1/2 front slope of the roof and 1/2 back slope of the roof. Runoff goes into two rain barrels, drains into a 4" pipe buried underground, goes to a small pump sump and is then pumped behind the workshop into a 4-tank IBC setup. The rain barrels are just buffers so that, if a hard rain dumps more water than the sump pump can handle, it temporarily fills the barrels instead of overflowing onto the ground.

The four tanks hold a total of 1100 gallons and I capture 600 gallons for each inch of rainfall. So two inches will fill the tanks from bone dry. The four tanks are daisy chained together with 1-1/2 pvc, which allows them to fill equally. The pipes have to be drained in the winter or a freeze will crack them.

Debris is filtered from the pipes by dropping them through a kitchen strainer and a paint strainer, before entering the tanks, and the irrigation pump pushes water through a 50-micron filter so that no debris will clog the drip tubes and emitters that water the plants. Been working great for two grow seasons. I plan to add at least two more tanks this year because there were a couple of times last year that I ran them dry and had to irrigate from our well water. If you use a pump instead of gravity-feed the irrigation, you have to add a check valve on the inlet side of the pump, otherwise the pump will create back pressure and blow bubbles in the tanks or blow out a pipe. Found that out the hard way.

John C Daley wrote:The link in my signature takes you to a detailed distillation of the Benefits of rainfall collection.
In Australia I have IBC,s collecting water which I pump across to a 20,000L tank.
It sits in full sunlight and has never had algae.
From memory algae needs nutrients to establish and grow, so what source of nutrients would be around if you have algae?
bird poo is one.
I always run a first flush filter and I wonder if that is why I dont have a problem?