Recently, I helped a friend design and install his rainwater harvesting system. This was made much easier by my recent experience in Tucson, Arizona. The water harvesting certification from Watershed Management Group was filled to the brim with knowledge, and math. But I digress…
Rainwater Harvesting System:
So, my friend Mike contacts me and asks if I would talk rainwater harvesting with him. You can guess what I said, I’m sure. Several hours, beers, and napkins later we came to this. 5 IBC totes (he wanted to use these because of future plans for a deck above) several hundred feel of 3″ PVC pipe, some 4″ PVC, and a 6″ PVC length for building the most awesome first flush ever! More on what a first flush is later…
Any container for water, be it, a cistern, rain barrel, or IBC tote, needs to be light proof. Meaning, no light can get into it. This is because if light does get in, you are guaranteed the very unrewarding job of cleaning up algae from the container. With these, we decided to go with 6mm thick plastic. We first removed the IBC totes from the cages and then wrapped them up nice and neatish.
Something to note, if you ever decide to do this, is the need to cut the top tabs that hold the cage to the plastic. Otherwise, no mastery of wrapping will save you.
The three photos above are examples of a first flush system. The water from the gutters goes to a Rain Head. This has a mesh that catches most large debris, such as leaves. From there, it goes down to the capped pipes. When these fill up, it then goes to the IBC totes. That is the first flush! Your roof collects a fair amount of contaminants, such as dirt, bird droppings, and such. When it first rains the first flush catches this dirty water and there for “flushes” the roof.
The two images on the left show what a wet system looks like. Basically, the water leaves the first flush and goes into the collection pipe. This, however, is lower than the top of the tanks. What happens is the pipe fills and the water rises up, or levels, on the other side. Permitting it to go into the tank. Not the easiest thing to explain, I know.
The vertical pipe on the left of the first image, and the vertical one on the right of the second, are the other end of the wet system collection pipes from the previous images.
Here, you also see the smaller 2″ pipes that connect all the IBC totes together and where the water will, eventually, be released to the landscape. We decided to use “no hubs”, the black couplers with clamps, so as to be able to detach and service all the parts.
All in all, this was a really fun project and the IBC totes have a total capacity of 13750 gallons. Which will last this landscape through the dry season and then some.
Till next time…
Hi, loved the article and have a similar system. I want to seal my pvc, where it goes into the tote so that when my totes fill up, over flow will go down the drainage system. Do you have a solution?
Thank you so much!
Cheers,
John
Hi John,
There are many ways to set these kinds of systems up and even more variables that would change the designs. Not knowing how your system is setup, I’m going to make some guesses:
If you don’t get very large downpours in your area, then I would suggest just using the bottom drains as the input, output, and overflow. So you have a 2″ pipe connected to the CamLock fitting going up over the height of the IBC totes, then dropping to your overflow location (drainage).
If you do get heavy rains, then using only the 2″ pipes will backup the flow of water and it will come out where you don’t want. Places such as vents, or your rain heads (if you are using them), or it may even back up all the way to the top of your downspouts. So you would need to use 4″ holes at the top as inputs and overflows in order to be able to capture as much of the rain as possible.
What I don’t recommend, since these are pretty thin plastic, is cutting into them to attach pipes directly to the walls. This works great in more traditional (thicker walled) cisterns. Best to use the CamLock at the bottom or the 4″ cap at the top. They both have their complications and adapters are always needed. Let me know if I understood you correctly and if I can further help! Always happy to talk about sustainable practices…
Hey Sergio,
Found this while searching for information on ibc tote rainwater systems and it explained things really well. In your last photo, is the overflow system visible? I was able to figure out the rest but once the tanks are full I can’t see where the excess would go?
Thank you!
Hi Jeremy! Sorry for the long time it took to reply… The overflow is on the right most IBC tank’s top. The others have the input coming in from the top and the 2″
pipes sending the water to the other tanks, but on the last one it’s the overflow. Hope that helps and let me know if you have any further questions.
Hi Sergio, how well will black plastic film hold against sun/UV? I am planning to instal 20 IBC totes on central coast of CA. Have 2 barns (4,000 + 2,000 sf) with metal corrugated roof and large gutters.