IBC - Large downpipe diverter or big overflow?

[SomewhatClueless]

Last summer we got a cheap IBC tank for rainwater collection (for veg garden watering). I did a "quick and dirty" hookup as soon as it arrived, so as to not waste the opportunity of a massive downpour due that day. We simply placed the IBC next to an existing water butt fed from a house guttering down-pipe diverter, then fed a short garden hose from the butt outlet tap into the bottom of the IBC tank via the main opening. I’ve attached a (very) basic sketch of this in case I described it poorly.

This worked last year, but I'm aware I was wasting a lot of potential water during brief downpours, as it was limited to the rate the water butt could supply through the standard garden hose (which I guess was even slower than how quickly the diverter could fill the butt).

The butt & tank are now dry, so this is the opportunity to do it properly/better. We'd like to re-use the water butt elsewhere and have the IBC tank fed directly from the downpipe, probably to be daisy chained to a second IBC in the near future. I realise the best way to get maximum flow of rainwater would be to simply have a downpipe go directly (via some sort of leaf catcher/grill) into the top of the IBC tank. The problem that gives me though, is how would I have an overflow that could take excess water away at the same rate?

I was thinking a compromise might be to upgrade the (very narrow) down-pipe diverter to something larger that could take more from the downpipe, while also removing the need for an overflow? The problem is, there doesn't seem to be such a thing. All the downpipe diverters appear to be much the same size, as I guess that's fine for a water butt. Does what I'm looking for exist? If not, any suggestions on how to handle the overflow (that would need to go back to the drain at the bottom of the downpipe?

 

[scbk]

I just run the downpipe/gutter straight into the ibc, not got any sort of leaf catcher/mesh.

Never bothered with an overflow, but you could drill a hole in the top of the ibc and fit a tank connector, you would lose a little capacity though

Toolstation

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If you connecting a 2nd ibc next to it you might want to daisy chain them via the main tap on the bottom, that way they will both fill and discharge at the same time.

 

[scbk]

Oh and if it's a clear ibc you need to wrap it in black plastic to keep the sun off the water

 

[SomewhatClueless]

I just run the downpipe/gutter straight into the ibc, not got any sort of leaf catcher/mesh.

Never bothered with an overflow, but you could drill a hole in the top of the ibc and fit a tank connector, you would lose a little capacity though

Toolstation

www.toolstation.com

If you connecting a 2nd ibc next to it you might want to daisy chain them via the main tap on the bottom, that way they will both fill and discharge at the same time.

Thanks. This will be from a pretty big roof area (bungalow), so I'm thinking if I didn't have an overflow, in a downpour (when it's already full) I'd be having a large amount of water spilling all round the tank, and that felt like not a great thing right next to my house! I guess that's not caused you an issue, or are you running this from a relatively modest roof area maybe?

I was also thinking that linking them from the main/bottom tap would seem sensible, though my partner is less convinced as she points out if one of them (or the connecting pipe) has any sort of leak, we'd lose all the water from both of them! This sounds like an opportunity for some sort of level monitoring/automation to me though!

Oh and if it's a clear ibc you need to wrap it in black plastic to keep the sun off the water

Yeah, it is clear and we started with it "naked", and then shocked by how much algae suddenly appeared! Then got a cheap cover from eBay - made a massive difference.

 

[scbk]

Thanks. This will be from a pretty big roof area (bungalow), so I'm thinking if I didn't have an overflow, in a downpour (when it's already full) I'd be having a large amount of water spilling all round the tank, and that felt like not a great thing right next to my house! I guess that's not caused you an issue, or are you running this from a relatively modest roof area maybe?

I've not got much rainwater collection on the house, it's mainly outbuildings, some are big, some are small. The main thing is trying to get water storage where you need to use it in the garden.
If that water wasn't being stored it would just be soaking into the ground anyway, but yes you might want it away from the house. You could even run an over flow to an area that you want well watered, maybe a pond, or plants in a greenhouse

If you're using a hose for watering, 3/4" gives you more flow than 1/2"

Reinforced PVC Water Hose 3/4" x 30m | Toolstation

Heavy duty high tensile polyester cord reinforcement 30m water hose. 3/4" diameter.

www.toolstation.com

Try and use quarter turn taps that are full bore and straight through with no bends





If you want to cover another ibc you can use black dpm, take it out the cage and wrap it like a giant present, then put it back in the cage

 

[StephenStephen]

You could do some back of envelope calcs on how full the tank will get.
(roughly a metre of rain falls annually, so each square metre of roof will theoretically fill your tank, but of course it'll only be a proportion of that because you'll be using the water many times a year)
You may well find that it is rarely full, and a hosepipe overflow as near the top as possible is sufficient.

 

[John D v2.0]

You'd be surprised how much water can go down a short length of standard hose pipe, even with only 20cm head. But of course if it's a decent size roof and the level is close to the overflow/top you will lose some.
Another tip I think hasn't been mentioned is you can keep the same level in multiple tanks by filling a short hose completely ( feed it into a bucket of water from one end then thumb over the ends) and then put each end to the bottom of a tank.
As long as the ends both stay under water it will equalise. The engineering bricks with holes in are quite good for weighting the ends.
Good luck, sounds like an interesting project!

 

[Trouble1980]

I have a similar issue. Recently got a black IBC to hold rainwater. I had to 2 x 220 butts in series connected to the down pipe of the garage.
I was going to try to connect the IBC to the downpipe. But now I'm considering leaving the first butt connected to the down pipe and diverter and then putting the IBC in place of the second Water butt....so that the down pipe will fill the first butt , overflow to the IBC and then when full the diverter will send the water to to the drain. There will need to be some changes in the levels of the first butt and diverter but I think it should work.

I'm raising the IBC high enough to get a watering can under the tap. then I'll get the butt lined up with the IBC and drill the IBC and connect using the connection pipe to the old water butt. Then adjust the divert to the right level on the down pipe. I have a full length of down pipe ready as replacement. I'm looking at getting a second IBC to connect on again.....

Anyone done anything like this?

Trouble

 

[Mr Chibs]

If I understand correctly, water from downpipe is going into 220L butt, then you will fit a pipe from 90% full level to IBC, then onto IBC2, IBC2 will have overflow to drain.

If this is right, you could just use a section of 32mm MDPE pipe or smaller, drill a hole into butt/tank and feed the IBC tanks from the butt.
Only issue will be reaching the back of the fittings to tighten it up.

If you have the Butt higher and run pipework, into the cap of the IBC's you could just use plumbing pipe with tee's and bends.

Something like this:

Link to IBC image

Any help? PS, I'll be doing something like this soon.