I have been trying to come with a design for a reliable water supply in an area that is prone to short power cuts almost on a daily basis and that is cheap to run. My current thinking goes like this…..

Inside the roof void of the house is a 200 litre cold water tank that supplies taps / showers etc. Hot water will be supplied from a solar powered system with its own hot water tank. The water pressure from the hot and cold tanks will be the same which should make it easy to use a thermostatic mixer tap for the shower.

The cold water tank will be filled from another tank situated on a tower about 40 meters away. The tower tank will hold 2,000 litres and will be about 1 meter higher than the tank in the house to allow a gravity feed for the house tank. This will mean that the top of the tower tank will be only around 5 meters above ground level so that it will be quite quick and easy to grow something to hide the tower. The tower tank will have a flotation on / off switch to trigger a simple pump that will draw the water from a well.

The other solution is to forget about the tower and have a pressurised system that draws water from the well and fills the tank in the house. I’m not keen on this because the pump is more expensive and will suffer more wear and tear as it will run intermittently as water is used. The tower solution allows for a cheaper pump that will run for fairly long periods of time – I think the on switch could be set when around 500 litres have been used from the large tank. The large tank will also act as a small reserve if the well starts to dry up.

Any comments, pros and cons gratefully received!

Check the pressure requirements for the mixer tap, it may be that the tap needs a minimum pressure on both hot and cold to function correctly (that is in addition to the pressures being the same..ish).

If the water head from your loft to the bathroom doesn't give enough pressure then you may need to consider either using manual mixing, or moving your shower to the ground floor.

I like the tower aproch because not only is pump cycling reduced but the water collects quite a bit of heat from the sun/air making it already tepid before you ever use it.

Make sure you screen the tanks against bugs and birds etc.

Stand your internal tank in a overflow spill tray with a run off to outide the building (this is in addition to the overfrlow from the tank). These things get isntalled and forgotten about so overlows can happen over years.

Put gause over all overflows to make sure insects, particularly bees and wasps don't set up home there and block water flow.

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Oh and check the local water salt levels (have a word with any nearby neighbours who have wells). The last thing you want is to spend a fortune building a brine water system (not uncommon in the NE of Thailand).

If your water salt levels are too high then you may need to consider a rain harvesting system.

But in anycase, use HDPE or other polymer tanks in the house. Stainless steel tanks very often start to rust and leak around welds. Not the sort of thing you want above your bedroom.