Redoing my Rainwater harvesting - stick with IBCs or change to large tank?

[al_uk]

I've been happily using 12 interconnected IBCs for the last 8 years or so. They are in a couple of locations and different levels and interconnected by various pumps. I've paid almost no attention to it for the last few years.

We're having a spot of gardening done (read major groundworks) which gives me the opportunity to either

1. Put in a 10,000 litre underground tank in the middle of the lawn. Either concrete pre-cast, or plastic.
2. Extend our patio over an existing retaining wall and Build a block and beam concrete patio balcony and bring all 12 IBCs together semi-underground which will be nice and cool and dark and at the same level.


Both options I think will cost about the same.

Option 1 will cost around £3k for the tank and I reckon £2k? for the required ground works, concrete surround etc.
Option 2, will give us semi-underground storage for the tanks and pump etc. and the storage would add value to the house even if not used for IBCs. Although we're not planning to sell in the next 20 years! I already have all the IBCs and fittings, and pipe. I can also incorporate a "settling" IBC within the storage area.

Tending towards option 2, because I have everything, and know what I'm doing with it, and I can maintain it if needed.

I suppose we could build a tank but that might be more cost.

How much does a borehole cost?!

Any views?

[kristen]

Sorry for late reply, haven't been on here for a while.

I find it depressing how expensive it is to put a rainwater harvesting tank in, compared to just buying potable water on a meter and chucking it on the lawn ... would be nice if someone gave me a handout to stop me using drinking water and reduce the need for water company to have to build a new reservoir, or new housing estate down the road have lousy water pressure in mid Summer

We repurposed our old septic tank and routed all downpipes into it, and installed a digester for foul water.

Separately I blagged some circular corrugated (grain silo type) water tanks from a commercial greenhouse that had fallen into disrepair, and put a new liner in it.

10K Litres sounds tiny to me ...

I have some IBCs which predate the rainwater harvesting project. Fittings to join them together were expensive, so I resorted to cheap hose and siphon.

[spencer1885]

A bore hole is about £4500
We use ex orange juice containers 1500 litres
This has worked for 20+ years but we do have a large roof for collection
All the waste water is pumped to a reed bed which sorts the grey and black water
All these things only work if you have the space
Cheers
Matthew

[al_uk]

Quick update:-

I decided to stick with the IBCs and put a block and beam over them, and an extension to the house on top of the block and beam.

I don't have the height to put the IBCs in the space as they are.

Is there any issue with using the IBCs without the fork lift truck base? The plastic tank would sit directly on my concrete floor, with the metal cage around it.

The left hand side of the photo shows the plastic tank and cage - it would be that sitting on the concrete base. Obviously turned back upright!

[djs63]

 As someone who is a complete non expert who has had one IBC for years I guess that
a concrete floor will provide better physical support to the plastic than the metal frame
But
concrete may allow the IBC contents to freeze more easily compared with a tank suspended a little bit above floor level

[al_uk]

Ah yes I'll have to keep an eye on the freezing, but should be better than it is today out in the open.

I am mainly questioning whether the metal cage will stop the tank bulging without the bracing of the base being there.

Cheers.

[Countrypaul]

I used an IBC with the top cut off as a compast heat for many years (not sure maybe 25), just the metal cage around it to prevent bulging with no problems, still have it today though not in use anymore so provided the iron worms dont get aat it should be no problem on a concrete base. If the base is below ground level and the top is covered highliy unlikely to get frost problems in this country.

[Bodidly]

Before building in the IBCs check for UV damage. I use them for various jobs and some of them have become very brittle and just shatter.

[al barge]

I also had low height space issues with IBC's to store water. I would expect for water at least, without the cage being held together by the base the tank would bulge out quite dramatically, maybe even split. I made square birch ply bases, and used m6 insert nuts from the other side to bolt the frame to it. Much easier to slide around into place on flat surfaces, and can still be placed on a pallet if ever needed.

[Philip R]

interestimg to here that IBCs are suffering from UV damage.
I am seeing many green plastic domestic heating oil tanks breaking down ( Bleaching and cracking ) from UV radiation after less tha 10 years.
Philip R

[al_uk]

Did a test today. Plastic tank surrounded by the metal cage, and sitting on the thin metal base, but the cage was not screwed into the base.

No bulging that I could detect after filling the tank. The metal base also lifts the filler valve very slightly so it is not stressed against the floor. And it all fits into the available space with no need for a ply base.

If I do get bulging, then I could always attach the cage to the metal base with nuts and bolts.

Thanks for the help all.

20mm of clearance!

[al_uk]

Wondering how best to arrange for the tanks to overflow in a place of my choosing and not just all over the floor.

If I do this with a pipe at position 1 standing up to the level I want to overflow at, will the pump just suck air? What about at position 2?



I could just drill a hole at the top of the side wall of one of the tanks, and run a pipe from there, but trying to use the same pipe for filling, emptying and overflow.

[sbchapman]

Assuming I've understood the drawing correctly and that you set you rainwater diversion level slightly higher than the overflow level, the advantage with 2  is that it reduces stagnation in the IBCs furthest from the pump.
Though, I think stagnation characterised by 'green' water in the summer shouldn't be a major issue as the IBCs are covered and cool, but it could help reduce bugs.

I had two (much smaller!) setups with both options. I ended up reconfiguring them to ensure any water used was pulled from the furthest tank from source to ensure through flow otherwise the end tank rarely got refreshed; it was previously 'diluted', depending on how much the overall level dropped.

[renewablejohn]

interestimg to here that IBCs are suffering from UV damage.
I am seeing many green plastic domestic heating oil tanks breaking down ( Bleaching and cracking ) from UV radiation after less tha 10 years.
Philip R

IBC's do become brittle through UV degradation but it is random and in my experience takes about 20 years. I am quite a big user of IBC's having approx 2000.

[phoooby]

I wrapped my IBC's in black plastic over the summer. Take them out the cage and wrap them like a present and the put it all back together. Main reason was to stop the water going green but it would undoubtedly stop the UV damaging the tank plastic as well. Not sure how long the black plastic will last in sunlight. It was DPM stuff so quite heavy duty.