How to connect IBC tanks for rainwater collection?

Dear Fellow Permies,

I have just started to set up rainwater catchment system that will collect rainwater from my cabin's roof.

I want to use 6 IBC totes, as shown on this picture:



I need some advise on how to connect the totes to make them function correctly.

Water from the roof will be coming through leaf eater filter and first flush diverter, so I hope it will be pretty clean.

I would like these tanks to work as one big tank, so I assume all have to be connected together.
I would like to avoid making any holes in the tanks.
I want to connect them by adding pipes that connect their outlets with valves at the bottom of each tank, while keeling the upper inlets tightly shut (except where water enters first tank preferably).

I'm not sure how to make the air escape from the tanks when water level rises. Some people add a small pipe that goes higher than a top of the upper tanks, but that requires to make holes either in tank or each lid.

What if water enters the tanks from a bottom? And then overflow serves as air escape route until tanks are full?

Can someone point me to a drawing of similar setup?

Anything esle to take into accont when setting up such system?

Unfortunately I have never seen a setup like yours that doesn't involve new through fittings so the water runs from tank to tank and ends up in one outflow valve.

I use a similar set up but I have installed upper through fittings (boat supply stores have really good ones that don't leak when installed correctly).
Mine fills the top tanks first then fills the lower tanks, they are plumbed similar to a battery bank.

You could do what you want to do without extra holes but you will need the upper tanks set on a rack far enough above the lower bank of tanks to allow pipe to be run.
The air issue will require a vent pipe or two.

Here is my current design, I'm not sure if it will work as intended, but I'm optymistic

Ok, now if you are filling from the bottom how does the water move to the next tank in the line?
for the top tanks you could use the top filler cap connected to the next in line lower outlet valve, this will work for the top row and the bottom row but you also want to get the water to flow from the top tanks to the bottom tanks Yes?

Please follow water flow starting at the word "Inlet".
Water goes down and enters upper tanks through open valves.
When it reaches level determined by "Top water level" it overflows to lower tanks.
When it reaches top water level pipe for lower tanks, all six tanks are full almost to the top.
Air escapes through not fully closed lids.
No holes in a tanks, since all pipes are connected to the bottom outlet of each tank.
Am I missing something?

Edit: in order for it to work, both additional valves marked yellow need to be closed.

Does each tote have it's own shutoff valve? Id suggest it so you can isolate a problem vs losing all the water.

The main concern with your drawing is the lower "slightly loose cap".  Seems like the whole top level will leak out thru it. If the top pipe elevating before going to bottom is the solution, it looks like a siphon to me.

I have a one layer 3 tote set up. If i added another layer i would put the water inlet into a top cap. That inlet would serve as the draft (air exits so water can go in). I would connect all the totes to one line as you have shown. I would have a shutoff at each tote.

You may want to check out this guy's set up or research other ones on YouTube.

My totes have little fittings in the lids so you can put a breather in the lid instead of having an open pipe or loose cap.  As long as there is an air escape or breather in all the lids, you can fill all of them from a connected bottom system.  

I think Wayne's correct on the potential siphon.  I'd suggest a breather or air inlet in the horizontal pipe that leaves the left most upper IBC.  It may have to be rather big to accommodate a sudden stop in the rainfall.

The upper tank set will only get as full as the outlet of the third tank so keep that outlet as high as possible.  

Valves on each IBC is a good idea but it looks like yours came with them so you're already in good shape.  Figuring out which type of threads you have on the IBCs is a pain in the butt.  This guy's video helped me figure mine out.

My only other thoughts are that all 6 at the same level would be a fair bit easier to plumb than stacking them (if you have the room).  Be sure you have a good foundation for them if you stack them.  That's a lot of weight.  Good luck!

I agree with Wayne and Mike on that left pipe going down to the lower level will work as a siphon without a vent in the pipe. I'd make that elbow that goes down from the top level into a "T" and run a piece up to the level of the cap on that tank. This would make that pipe a feed to the lower level and I'd do the same thing for the elbow for the overflow. Otherwise you are looking to dump most of your water once your system hits that full point and it starts to run the overflow. Surface tension of water can do some crazy stuff in piping. Turning those two key elbows into a vented "T" ought to make that setup work rather awesomely.

wayne fajkus wrote:Does each tote have it's own shutoff valve? Id suggest it so you can isolate a problem vs losing all the water.

The main concern with your drawing is the lower "slightly loose cap".  Seems like the whole top level will leak out thru it. If the top pipe elevating before going to bottom is the solution, it looks like a siphon to me.

Put an open "Tee" in the top tube (to allow air in) and it will stop the siphon.

Actually, you could just drill a hole in the tube and get the same effect.  ANything that lets air into the pipe will break the siphon.

wayne fajkus wrote:Does each tote have it's own shutoff valve? Id suggest it so you can isolate a problem vs losing all the water.

The main concern with your drawing is the lower "slightly loose cap".  Seems like the whole top level will leak out thru it. If the top pipe elevating before going to bottom is the solution, it looks like a siphon to me.

Yes, there is a nice ball valve in each tote.

The top will not leak through the lids, since water will never go higher than the levele of the pipe marked "top water level".

Good point with the siphon guys, thanks for that, I need to check it out. Either a T or an elevated narrow pipe is not a problem to add.

This system will not have a pump, so stacking tanks gives a little bit more water pressure. I have n room for six in a row anyway.
The tanks will act as a thermal mass as well, if you look at the picture you will see that they are located under a roof attached to the house (a kind of roofed veranda). This space will be converted into a "greenhouse" attached to the house. It will heat the house in winter and thermal mass on the tanks is supposed to help with that.
The tanks stand on a solid ground, so weight of stacked tanks is not an issue I hope.

I use a lot of these tanks, but you need to check the pricing against a single bigger thank.
I am responding since I see many problems with the set as you have described.
As mentioned having them above each other is looking for trouble, each will weight 1000kg which is about 1/2 ton in Imperial measurements.
In my opinion, 6 on the ground, with a net work of 2 inch, 50mm,pipes connected via the ball valves is best.
By having the water enter one opening via a screen it is kept simple.
An hidden cost may be the adaptors for the ball valves, some are simple, some are difficult and expensive.
So its best to check what you actually have, since there is too much variation to make any suggestions on my part.
By having the single system connecting the tanks, filling and draining is made easier.

Well, I have the tanks already, as well as IBC to 50 mm connectors, it has been a fraction of the cost of a bigger tank at least in my part of the world. Each tank has its own ball valve already, so I just need three more for this setup. As I have said before, there is no option to fit six tanks in a single row and to be honest I do not see how stacking them is looking for trouble, since they are designed to be stacked for transport and storage. Each (when full) will weight approxmately 1050 kg (a bit over 1 ton), which is not that much, especially when as in this case the tanks are on a solid foundation. What kind of trouble you mean? Risk of tank flipping over? Risk of leaks?

Hi Richard, I had another thought on your system.  You are stacking them to get more water pressure.  That reminded me to look at the yellow valves in your drawing and the overflow.  

You will have higher pressure if you open the upper yellow valve and use up that water.  But the lower tanks will not have higher pressure since they are separated from the upper tank by the anti-siphon system we just convinced you to do.  I guess that doesn't matter because the pressure would drop anyway once the upper tanks are empty.

I am sure someone on youtube has done a set-up that is very similar to what you want to do.  I'd just poke around there for a while to see if something looks good.

A couple more thoughts...  If you could make a watertight connection at the top of the three lower tanks (in the lids) and plumb an air vent that rises up 4' to be above the "maximum water level" of the upper tanks, you should be able to then fill all 6 tanks and have them hydraulically connected and then have the full pressure of the upper tanks as you empty the lower tanks.  Once the uppers are empty, you'd be down to the natural pressure of the lower tanks but at least you'd only have one outlet to worry about.  

If the overflow was connected to the upper outlet of the upper left tank, it may give you maximum water storage.  You'd probably want to add a siphon breaking "tee" at the top of that overflow as well.  Here's a very crude sketch of the idea:

Thanks Mike, I have spent some time on youtube before bothering you guys. And I know that the vent idea you suggest above is widely used. However, in order to implement it you have to rise upper tanks about two inches above lower ones, in order to make a room for an elbow and jhalf inch pipe that serves as air outlet. THis is due to a fact that when tanks fill up they "swell", the lid goes up and the air pipe is being crushed.
Rising upper tanks and placing them on planks makes all construction less stable - the bottoms of the cage of my tanks have such shape that when when stacked they cannot move sideways, unless lifted. Yu are losing that fonction when you rise upper tanks. I could use a flexible hose instead, but it makes all system more prone to leaks.
I will think more about it though, thanks for a drawing.
By the way, when the upper tanks are empty, I can always use a solar sump pump to move water "upstairs" from lower tanks ...

That's a shame about the swelling, Mike's system seems to provide the pressure of the upper tanks throughout the system, solve the problem of venting, and do so with the least amount of pipe, joints, bends (therefore points of failure) and the least complication. It's an elegant solution.

What if the air pipes weren't pliable? Instead of hose could you use little 1/2inch pipe? If so it looks like you would have room for a short pipe, elbow pipe out between totes, then another elbow to bring it vertical.. The pic didn't show if your tanks have standard vented 150mm thread lids or no.

Maybe I'm underestimating the extent of the 'swell'?

Are you going to have a pump for the collected rainwater, or will everything be gravity fed? If you are doing gravity fed, I would suggest using cider blocks to raise all the tanks to the same elevation.

Cody DeBaun wrote:That's a shame about the swelling, Mike's system seems to provide the pressure of the upper tanks throughout the system, solve the problem of venting, and do so with the least amount of pipe, joints, bends (therefore points of failure) and the least complication. It's an elegant solution.

What if the air pipes weren't pliable? Instead of hose could you use little 1/2inch pipe? If so it looks like you would have room for a short pipe, elbow pipe out between totes, then another elbow to bring it vertical.. The pic didn't show if your tanks have standard vented 150mm thread lids or no.

Maybe I'm underestimating the extent of the 'swell'?

The most comprehensihe youtube video playlist on this topic (link was posted above) contains a film that addresses just that - air pipes being crushed by swelling tanks. So even for 1/2 inch pipe the upper tanks have to be raised. My lids are 150 mm but they do not have any vents.

John Wolfram wrote:Are you going to have a pump for the collected rainwater, or will everything be gravity fed? If you are doing gravity fed, I would suggest using cider blocks to raise all the tanks to the same elevation.

I would love to raise the tanks on cinder blocks, but tere is not enough space for that between the top of the tanks and the roof, just enoug to fit 50 mm pipes and elbows.

I want mostly to use gravity but I do not exclude possibility to use solar powered pump as well. In a future I might build a "water tower" - a single IBC tank placed 5-6 meters above the ground to have at least 0.5 atmosphere of pressure. Then, I will be able to keep it full by pumping water from these 6 tanks with a cheap solar sump pump when required. But this is not a part of a current project yet.

Richard Gorny wrote: I know that the vent idea you suggest above is widely used. However, in order to implement it you have to rise upper tanks about two inches above lower ones, in order to make a room for an elbow and jhalf inch pipe that serves as air outlet. THis is due to a fact that when tanks fill up they "swell", the lid goes up and the air pipe is being crushed.

If there really isn't any room above the lids to plumb a vent, how about drilling into the side or top of the tank in a convenient place and installing a bulkhead fitting.  Something like THIS?

Mike Jay wrote:

Richard Gorny wrote: I know that the vent idea you suggest above is widely used. However, in order to implement it you have to rise upper tanks about two inches above lower ones, in order to make a room for an elbow and jhalf inch pipe that serves as air outlet. THis is due to a fact that when tanks fill up they "swell", the lid goes up and the air pipe is being crushed.

this

If there really isn't any room above the lids to plumb a vent, how about drilling into the side or top of the tank in a convenient place and installing a bulkhead fitting.  Something like THIS?

Yes, this is of course possible, but I would like to explore all other options before drilling any hole in a tank.

Instability iwas my main concern, if the base cannot change its composition if it gets wet from a leak or similar, then you should not have an issue. So concrete would be best.
But I have seen the ground move because its got wet.
The other issue is the complication you seem to be making.

Why store them inside anyway?
Here in Australia we would keep them outside as a norm?

John C Daley wrote: Instability iwas my main concern, if the base cannot change its composition if it gets wet from a leak or similar, then you should not have an issue. So concrete would be best.
But I have seen the ground move because its got wet.
The other issue is the complication you seem to be making.

Why store them inside anyway?
Here in Australia we would keep them outside as a norm?

Here in Poland, we have up to -30 degrees Celsius in winters, so outside they have to be emptied in November and stay empty until April, unused for 5-6 months. Moreover, as I have said above, tanks full of water will serve as a thermal mass in a greenhouse.

I cannot imagine how to live with -30 deg C. Its madness in my mind.
How is it possible

John C Daley wrote:I cannot imagine how to live with -30 deg C. Its madness in my mind.
How is it possible

Pretty easy actually, just have to dress properly.

Yesterday I had a chance to work on my rainwater catchment system again. I have cut old pipes and I have installed rani heads (Leaf Catcher) and first flush diverters.

Regarding tanks, I have decided to follow Mike Jay's advice from above. The majority of pipes are in place now, I need to add an outlet valve, air vents for lower tanks and to connect inlet pipe to the first flush T section. I'm lacking some parts for that, so it will take some time to get them, but as soon as they arrive, it will be finished quickly.

Then, the next step will be filling the tanks and checking for leaks.

Richard Gorny wrote:Here is my current design, I'm not sure if it will work as intended, but I'm optymistic

My friends had a system hooked up like this and the lower tanks would bulge. We fixed this by putting an anti-backflow valve in between the upper and lower connections. The upper tanks fill first then overflow into the lower and the take off side has the valve right before the T connection. This allows water to be drained from both banks. The higher pressure means the uppers drain first but it works.

Good luck,

Jason

It doesn't seem reasonable to be spending so much money on all of the fitting I see involved both in the above postings.....and also in the suggested video.


All that is needed is one tank with fittings and then siphon lines from one tank to other tanks.

One inch black poly works well. 3/4, 1/2 or even old sections of garden hose would work well too. I store about 5,000 gallons this way but I do have two tanks not in the siphon system. One is 1,100 gal and the other is 1,000.

To get water from the siphon system you can have a faucet on the bottom of the main tank for low pressure water.

To get pressure water I siphon from the main tank to a 55 gallon barrel and then pump with a small sump pump.

The 55 gallon is also convenient for mixing urine into the irrigation water. I have a tee at the top of a 5ft. piece of 3/4 pvc and one end directs back into the 55gal with a valve and a nozzle for jet agitation.

John C Daley wrote: As mentioned having them above each other is looking for trouble, each will weight 1000kg which is about 1/2 ton in Imperial measurements.

These tanks are DESIGNED to be stacked while containing fluids that are often much heavier than water.  I get these for about $30-$40 ea that previously contained concrete colorant, that stuff is nearly twice as dense as water and they are typically stored at least two layers high.

The only real issue would be to make sure whatever floor you have can support the weight.

Richard Gorny wrote:Yesterday I had a chance to work on my rainwater catchment system again. I have cut old pipes and I have installed rani heads (Leaf Catcher) and first flush diverters.

Regarding tanks, I have decided to follow Mike Jay's advice from above. The majority of pipes are in place now, I need to add an outlet valve, air vents for lower tanks and to connect inlet pipe to the first flush T section. I'm lacking some parts for that, so it will take some time to get them, but as soon as they arrive, it will be finished quickly.

Then, the next step will be filling the tanks and checking for leaks.

Hi Richard- know this is an old post, curious if your system working well? have a 2 stack system I'm working on as well. Any words of wisdom?

Scott McMillan wrote:

Hi Richard- know this is an old post, curious if your system working well? have a 2 stack system I'm working on as well. Any words of wisdom?

Hi Scott,
The system is working excellent, but I have encountered three issues:
- too much organic matter entering tanks, despite first flush filter: this is due to enormous amount of pine pollen (I'm in a middle of a forest) that passes by screen and the filter. It can be solved by increasing the volume of the first flush filter and installing screens on your gutters (not so much for pollen, but for leaves)
- upper tanks are easy to clean inside, but if you ever want to clean lower ones, you have to disassemble the system
- too low pressure to gravity feed drip irrigation, when water level in tanks is low: I have installed very small solar powered pump that solved this issue.
Not a big deal all three, I'm still happy with.

Richard Gorny wrote:

Scott McMillan wrote:

Hi Richard- know this is an old post, curious if your system working well? have a 2 stack system I'm working on as well. Any words of wisdom?

Hi Scott,
The system is working excellent, but I have encountered three issues:
- too much organic matter entering tanks, despite first flush filter: this is due to enormous amount of pine pollen (I'm in a middle of a forest) that passes by screen and the filter. It can be solved by increasing the volume of the first flush filter and installing screens on your gutters (not so much for pollen, but for leaves)
- upper tanks are easy to clean inside, but if you ever want to clean lower ones, you have to disassemble the system
- too low pressure to gravity feed drip irrigation, when water level in tanks is low: I have installed very small solar powered pump that solved this issue.
Not a big deal all three, I'm still happy with.

Many thanks for the reply and the insight! curious on the final piping method- looks like you were able to plumb it where all tanks work in unison as opposed to valve separating the upper and lower tanks? ideally I would like for the whole stack to work together to one outlet, this was the only post I could find with a 2 stack program.

Scott McMillan wrote:
Many thanks for the reply and the insight! curious on the final piping method- looks like you were able to plumb it where all tanks work in unison as opposed to valve separating the upper and lower tanks? ideally I would like for the whole stack to work together to one outlet, this was the only post I could find with a 2 stack program.

Yes, all my tanks are connected, with all their valves open they work as one. There is also a single outlet. Water enters the lower horizontal pipe and enters lower tanks through open valves. In the same time water rises in the vertical pipe that connects lower and upper horizontal ones. If you close lowet tanks valves, you can fill only upper ones, but I actually do not use that option.

You can see more details here, starting at 2:45

Hi Richard,

Many thanks for your insight on this- most of the work is about complete. here is the layout I did. hopefully last question since you've had yours in operation. did you do any additional sealing other than using the O ring to the lower tank lids with the vents? any issues with leaking since these fill past the cap?
Just a potential for the upper to drain out if not a real tight assembly? can't appreciate your help enough, no other assembly quite like it I could find!

Hi Scott,

I did not use any additional sealing in my setup.
So far, I had three incidents:

- after some time, when tanks were full, water pressure has dislocated lower right elbow and water started to leave the system forcibly. I have heard the noise, put elbow back in place and tied the junction with hay string to keep it better in place

- very heavy inflow of stormwater has disconnected overflow pipe from its socket. I have placed a heavy object on top of that junction to keep it in place

- I have stumbled upon water outlet valve, removing it from its socket, I have put it back in place.

One of the reasons for doing it all this way is that I want to be able to disassemble this system easily if a need arises (cleaning, broken pipe/tank, etc.) therefore I do not use any sealant and glues. If you want to make it more sturdy and secure, use silicone glue for aquariums perhaps.

Hello Richard and Scott,

Great job on building such wonderful systems. It is still unclear to me how you vented the lower totes in your systems. Please provide some clarity on your approach.

Thanks

Hi Vern,

1. I have made a hole in the top of the IBC tank
2. I glued 1/2 inch elbow to the hole
3. I glued a short piece of 1/2 inch pipe to the elbow
4. I glued another elbow to the pipe
5. I glued a long piece of 1/2 ich pipe to the elbow. This pipe is vertical and ends about 5 inches above the top of the upper IBC tank.
6. I have secured this pipe to the upper IBC tank
7. I have put a gauze on top of the pipe, secured with rubber band. It lets air our but stops bugs from getting in.

Hi Richard,

Thank you for the fast and thorough reply. This approach allows the tanks to remain in their most stable position by not requiring the upper totes to be raised. Great solution.