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How to build a rainwater tank system from IBCs?


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When we built the basement, we needed to run a set of external stairs up to ground level.

 

Rather than have these awkwardly appear in the garden, we built a 3x4 m box around them with the plan to put IBCs in the bottom for rainwater harvesting and to run a deck over the top and create a mezzanine level deck. it is west facing so should be a shaded sun spot in the evening.

 

All the roof rainwater is currently piped through this area in 110mm pipe on its way to a soakaway. 

 

I now need to buy 4 1000l IBCs and plumb them together to allow the rain water to enter the top (via some kind of filter) and have excess water go to the soakaway.

 

I've made electrical provision for a submerged pump which will be connected to an outside tap.

 

It's now time to order the tanks and figure out how to plumb them together. 

 

Looking to buy here but quite clueless on the fittings and sundries I will need but beyond that I'm pretty clueless!

 

Help please :)

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You can often get second hand IBC tanks much cheaper than new. Around here they go for about £60.

 

Often the second hand ones have had some kind of toxic chemical in them - but for what you are planning that wouldn't matter too much after a rinse out.

 

I know its supposed to be easy to connect a bunch of IBC tanks together so they act like a single store (though I'm clueless about the details on that!). You have to be careful about relative levels between them though.

 

Are the IBC tanks going to be burried / underground? You have to give them some help if so as they aren't designed to take much inwards pressure and can collapse.

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They will live in this big concrete box so will be quite safe, they're not strong enough to be buried directly in the ground.

 

I plan to have them in a 2x2 configuration. There's 1.5m between the floor and deck (which will stat just underneath the light well window) so some room to manouvre. The incoming rain pipe is just over 1m off the floor.

 

IMG_1167.JPG

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Depends where you are but I have sourced 5 for £130 delivered (Sheffield) that have been used for food use and steam cleaned.

 

IBCs have standard fittings which is a 63mm coarse thread - you can get these with a 25mm MDPE adapter already on them, and then with 2 tees between them you can connect all 4 together for about £40 of fittings and pipe.

 

You will need a calmed inlet on the first one - I would put an ordinary 110mm low back P trap on the inlet and then take an overflow from an opposite one around 100mm below the tank top - you can do this with a flanged outlet (check Koi Carp suppliers for cheap ones..) and then the flow will be through a couple of the tanks. 

 

There is enough capacity on 25mm MDPE to take a lot of rainfall so don't worry about connecting with anything bigger than 25mm (unless you have some 32mm lying around...) 

 

Put the pump in the tank with no connections ie not the one with the inlet or overflow, and a simple 10" 5 micron filter between the pump outlet and the tap  will mean you keep most of the crud out of the tap/hose.

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Thanks all - I'm in Maidenhead, Berks.

 

I have quite a bit of spare 32mm MPDE as you can see in the pic so can use that to make connections and can probably scrounge some 25mm also.

 

Regarding incoming filters - that IBC firm offer two types of filter, vertical and horizontal (as this will be for garden use, I'm not going to get too fussy on the degree of the filtration).

 

Might get away with the cheaper vertical one if I could get a tighter 90 bend on the incoming 110mm pipe, failing that, the more expensive horizontal one would work where the rain pipe comes in. Either way, will probably move  the pipe closer to the wall to maximise space for the tanks.

 

 

 

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If you have 32mm then use that...!

 

Those vertical filters are the wrong type, they are for downpipes. The horizontal one will work but its silly money - you can get them from Germany for about E85 or pick this sort up 

 

http://www.ebay.co.uk/itm/IBC-Rainwater-filter-Cover-filter-Lid-DN-225-Arch-89-DN-70-Reduction-DN-50-/112406930727?hash=item1a2bf9a527:g:n9QAAOSwYHxWPgJs

 

 

IBC to 32mm are cheap enough - the ones with the tees fitted can catch on some of the deeper tanks 

 

http://www.ebay.co.uk/itm/IBC-ADAPTER-S60X6-2-Coarse-Thread-to-32-mm-Straight-MDPE-Compression-Fitting-/291687238158?hash=item43e9ea0a0e:g:3CcAAOSwll1WxKUe

 

 

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That's great Peter. So the filter you show above goes straight into the top of the IBC?

 

Looks like it would need cleaned out pretty regularly, unless I'm missing something. The expensive one I highlighted above looked to be self cleaning to a degree as the debris would get flushed back into the soak-away pipe. Will look for a cheaper alternative.

 

This looks like the right kind of MPDE T to join the four tanks together at the bottom (one T per pair of tanks and then join the Ts together, all on 32mm MPDE).

 

Just need to think how how to assemble it all, wondering how to get the P trap in the first IBC.

 

Where did you get your IBCs from originally?

 

 

 

 

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3 hours ago, Bitpipe said:

 

That's great Peter. So the filter you show above goes straight into the top of the IBC?

 

Looks like it would need cleaned out pretty regularly, unless I'm missing something. The expensive one I highlighted above looked to be self cleaning to a degree as the debris would get flushed back into the soak-away pipe. Will look for a cheaper alternative.

 

 

Correct although with a deck you could easily enable that ..!

 

Dont forget the self cleaning ones dump the crud into your soak away -  ideally you stop the big stuff at the gutter, smaller at the downpipe and the last bits at the tank

 

 

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3 hours ago, Bitpipe said:

Just need to think how how to assemble it all, wondering how to get the P trap in the first IBC.

 

Errr if you go with the big filter sock then the calming inlet is irrelevant. 

 

Tank 1 will be cloudy, tank 2 will be the better (overflow) tank 3 and 4 will be clearer as they should only get moved a little by water coming in and out of the 32mm connector. 

 

My tanks came off eBay from a place in Sheffield - sore subject as they are sat on a friends yard as the skip is still in the way so I can't get them in the ground ......  

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26 minutes ago, PeterW said:

 

Errr if you go with the big filter sock then the calming inlet is irrelevant. 

 

Tank 1 will be cloudy, tank 2 will be the better (overflow) tank 3 and 4 will be clearer as they should only get moved a little by water coming in and out of the 32mm connector. 

 

My tanks came off eBay from a place in Sheffield - sore subject as they are sat on a friends yard as the skip is still in the way so I can't get them in the ground ......  

 

Ah, I get it now.

 

The soakaway is a 5m deep, 2m wide concrete ringed structure so not that worried about it having leaves etc. No real way to intercept the rainwater now until it hits that big orange pipe. Have put hedgehogs in the gutters to also minimise leaf build up.

 

Right, I think I have a plan... need to start scouring eBay for cheap IBCs :)

 

Any recommendations on a decent submersible pump?

 

Thanks!

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Peter, any disadvantage in using a 110mm connection into tank 1 with this http://www.ebay.co.uk/itm/IBC-Cover-filter-Rainwater-filter-Lid-DN-150-HT-DN-110-mit-Serviceoeffnung-/112298123220?hash=item1a257d5fd4:g:sIYAAOSw-0xYOsoY aside from getting the 110mm pipe to the right place? I've got quite a few bends lying about that I can probably use.

 

Found the flanged outlet - do you solvent weld that to the IBC or just use a sealant?

 

 

 

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I'm going for a non submersible as we had a discussion on here about it as it supplies the house. You're slightly different as you don't care if it doesn't work as only the plants will die ..!

 

Cheap submersible pumps are just that - cheap ..! This would be fine Hyundai 540w

 

 

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2 minutes ago, Bitpipe said:

Peter, any disadvantage in using a 110mm connection into tank 1 with this http://www.ebay.co.uk/itm/IBC-Cover-filter-Rainwater-filter-Lid-DN-150-HT-DN-110-mit-Serviceoeffnung-/112298123220?hash=item1a257d5fd4:g:sIYAAOSw-0xYOsoY aside from getting the 110mm pipe to the right place? I've got quite a few bends lying about that I can probably use.

 

Found the flanged outlet - do you solvent weld that to the IBC or just use a sealant?

 

 

 

 

Nope that's fine..! Got the height to get it in ..?

 

Flanged tank connector (ABS one about £6-7..?) needs a couple of things. Drill a 115mm hole and try the backplate for size and mark the fixing holes - should be 4 or 6 - and drill those slightly oversized. 

 

Use some 5 min epoxy and bond some flanged nuts onto the backplate over the holes - makes life easy ..!! 

 

Straighten a coat hanger and feed it through the lid and onto the top hole of the ring of holes you've drilled. Two lines of silicone around the backplate and then  slide the backplate into the tank along the coat hanger through the top hole - should all line up nicely ..!

 

Two lines of silicone around the outlet plate and offer it up to the coat hanger ..! You can now reach through the open hole and align all the plates with 2 pan head machine screws. Do them up reasonably tight, then remove the coat hanger. Dob of silicone on the remaining 4 holes and screw them tight - remove the original 2 and do the same. 

 

Quick wipe round with with a cloth and as tight as a tight thing ..!

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1 hour ago, PeterW said:

I'm going for a non submersible as we had a discussion on here about it as it supplies the house. You're slightly different as you don't care if it doesn't work as only the plants will die ..!

 

Cheap submersible pumps are just that - cheap ..! This would be fine Hyundai 540w

 

 

 

You're right - doesn't need to be submersible as it can just sit next to the tanks inline with the feed to the tap. 

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1 hour ago, PeterW said:

 

Nope that's fine..! Got the height to get it in ..?

 

Flanged tank connector (ABS one about £6-7..?) needs a couple of things. Drill a 115mm hole and try the backplate for size and mark the fixing holes - should be 4 or 6 - and drill those slightly oversized. 

 

Use some 5 min epoxy and bond some flanged nuts onto the backplate over the holes - makes life easy ..!! 

 

Straighten a coat hanger and feed it through the lid and onto the top hole of the ring of holes you've drilled. Two lines of silicone around the backplate and then  slide the backplate into the tank along the coat hanger through the top hole - should all line up nicely ..!

 

Two lines of silicone around the outlet plate and offer it up to the coat hanger ..! You can now reach through the open hole and align all the plates with 2 pan head machine screws. Do them up reasonably tight, then remove the coat hanger. Dob of silicone on the remaining 4 holes and screw them tight - remove the original 2 and do the same. 

 

Quick wipe round with with a cloth and as tight as a tight thing ..!

 

You make it sound so easy :) So the flanged connector is a two part thing, that wasn't obvious looking on ebay. Learning so much on this thread!

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6 minutes ago, Bitpipe said:

 

You're right - doesn't need to be submersible as it can just sit next to the tanks inline with the feed to the tap. 

 

So you may want to still go for a floating pickup as it means you don't pull the crap from the bottom of the tank. Easily made using standard garden hose push fit connectors and a ballcock float....

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13 minutes ago, PeterW said:

 

So you may want to still go for a floating pickup as it means you don't pull the crap from the bottom of the tank. Easily made using standard garden hose push fit connectors and a ballcock float....

 

Did you used to be in the A-Team?

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12 minutes ago, Bitpipe said:

 

Did you used to be in the A-Team?

 

No I'm just so tight I make @Nickfromwales look generous ..!!

 

I hate buying "custom" parts at a premium price when you can make simple ones work - hose bits are cheap and have swivels built in already so why create yourself hassle and extra cost ..?

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5 minutes ago, PeterW said:

 

No I'm just so tight I make @Nickfromwales look generous ..!!

 

I hate buying "custom" parts at a premium price when you can make simple ones work - hose bits are cheap and have swivels built in already so why create yourself hassle and extra cost ..?

 

Just imagine what you could cook up in @JSHarris garage with his collection of ex military submersible spare parts..

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