Rain water harvesting system..... need to decide on pump......

Hi all....
I am in the process of building my rain water harvesting systen.
So far I have all the outside taps, all three toilets and the washing machine all plumbed on seperate white plastic pipework going to the old cold water tank in the loft. This cold water tank can hold 250 litres. (all my other pipework is in copper to avoid confusion)
(the cold water tank was repurposed for rain water as there is now a combi boiler so rendering the immersion tank and cold water tank superfluous... so I decided to re-use the cold water tank for being able to store an extra 250 litres of rain water.)
There are two cistern ball valves with isolation valves. One is for rain water and the other is for potable cold water supply. (There is a potable water supply to the loft in case we have droughts and I can switch between this and rain water for the loft CW tank.)
OUtside, I have all my guttering feeding into 8 off interconnected 600 litre IBC's. The reason why 600 litre IBC's were used is to use a narrow long dead end alleyway down the side of the house to hide these 8 off 600 IBCs. SO these will be stacked in a 2 high 4 long configuration.
I now have to choose a pump that will pump the rain water from the ground level interconnected IBCs up to the loft water tank. The pump must:
(a) be able to connect to 22mm pipework (b) Be able to pump from ground level up to the loft so that means a need a head of 10 metres (c) have an integrated pressure switch so it will start and stop automatically depending on what the ball valve in the loft tank is doing (d) be self priming
Any recommendations for a pump to fit the above criteria but without costing the earth?
I incidentally already have a Salamander shower booster pump and a spare CH pump in my possession in case these can be reused with modifications?
I can put this pump outside with the IBC's or in the loft next to the loft tank. Which is better and why?
Regards,
Stephen.
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On 09/01/15 18:32, Stephen wrote:

In the next zombie apocalypse, you will survive.
But seriously - nice setup!
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I would use an electric float switch in the loft tank to control it, and not a ball valve.
The ball valve on the main input can have a long drop ball, so it only starts filling up from the mains if the loft tank is nearly empty, and mains will only keep it, say, 1/4 full. When operating normally from the IBCs, the mains ball will be well under water. (Note that the mains inlet valve must still be mounted at the top above the overflow limit, hence the long drop ball valve, similar to used on expansion tanks where the level can rise well above the inlet fill level.)
I think such pumps usually sit submersed in the bottom of the lower storage tank, and have an integral float switch to cut them off if the tank runs empty.

That's why at the bottom. No pump can self prime at 10m above the water level - it would need to generate nearly a full vacuum in the pipe to suck the water up that high.

CH pump won't generate anywhere near enough pressure. A shower pump will, providing it generates over 1 bar.
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Andrew Gabriel
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On 09/01/2015 18:32, Stephen wrote:

You could use the Salamander pump as long as it was positioned below the IBCs; if you have it outdoors it would need to be wired appropriately. The CH pump would be less convenient because of the fittings, and might not generate enough "head".
If it were me, I would probably go for a 12 volt pump of the type used as bilge pumps in small boats or for pumping caravan / camper / narrowboat potable water. I would put that in one of the IBCs to avoid all the issues of priming. *As long as the header tank is not more than 30 feet above the IBCs* you could, in principle, "suck" from the loft but unless you have a positive displacement pump it will need priming.
Such things are in fact readily available
http://www.ebay.co.uk/itm/12V-WATER-PRESSURE-DIAPHRAGM-PUMP-3-3GPM-12-5-L-MIN-35PSI-Caravan-RV-Boat-Marine-/131397843064?pt=UK_CarsParts_Vehicles_BoatEquipment_Accessories_SM&hash=item1e97ebf878
Cheaper bilge pump:
http://www.ebay.co.uk/itm/12V-1100GPH-Bilge-Pump-Submersible-Yacht-Boat-Marine-Sea-Wave-Float-Water-Volt-/141428363296?pt=UK_CarsParts_Vehicles_BoatEquipment_Accessories_SM&hash=item20edc99020
And you need a level sensor in the header tank, to switch on the pump. Just search eBay for water level sensor.
If your pump is in the IBCs, you need to decide whether to use a mains water level sensor to power the 12 volt power supply for the pump (meaning you can wire that part in lighting flex or 1 mm t+e with the power supply near the pump) or do you do it all in 12 volt DC.
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On Friday, January 9, 2015 at 8:52:21 PM UTC, newshound wrote:

Whatever pump you use make sure it is frost-proofed. I've had two destroyed by frost in recent years. Pump now sits in its own wee house mounted off ground wit lots of insulation.
I still turn it off and drain it down at the start of the frost season as its only used for the garden so has no use during the winter and the bloody pumps are expensive. ( we need high pressure)
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I have a similar thing. The best way is to use a sumbersible pump. Lots at Machine Mart.
Easy to install/remove. Can have a float switch to protect from dry running. Cheap. No shafts to leak. Available suitable for cold oxygenated water (ie non rusting plastic) Protected from frost as it's in the storage tank.
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I have a similar sort of thing. The best thing to use is some sort of submersible pump in your collection tank Cheap, no leak problems, corrosion resistant and out of the frost.
The pump can come with a float switch to stop it running dry. You can buy another to mount in your delivery tank to switch off when full
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