Potable water storage tank (Borehole supply)

[Kuro507]

We moved into a house just before Christmas that has a private borehole supply.

 

Design consists of a pump at the bottom of a borehole that is activated when the pressure in the system reaches 3 bar, it then continues until pressure is back up to 4 bar and then cuts off.

There a a metal storage vessel with a large rubber bladder in it, to help maintain pressure in the system and I believe to also reduce pump cycling.

Supply then goes to a cylinder with media in it to reduce the PH level, then onto a single in-line filter and finally to a UV steriliser tube.

 

I'd say this all works pretty well.

 

My concern is we have no resilience in the system, if the pump fails we would have no fresh water once the pressure drops.

We are also working on the garden, so drawing much more water while watering new plants and lawn, than we have done previously.

 

I'd like to cost up the option of fitting a potable water tank, to provide us with an amount of fresh water in the system.

 

I can see a few options here, one would be a unpressurised tank that simply has a float valve, the borehole pump runs until the float valve rises indicating a full tank. Then we would need a new pump to take water from this tank into our existing system (assuming the tank had unfiltered water straight from the borehole).

   Disadvantage: tank would contain water that has not been sterilised or filtered, so may need emptying sometimes and cleaning?)

   Advantage: Probably easier and cheaper to buy an unpressurised tank?

 

Alternatively I could fit a tank could be after the UV steriliser, which would then contain clean potable water, but would need to be pressurised up to 4 bar?

   Disadvantage: likely much more expensive   

   Advantage: no extra pump required, tank may not need regular cleaning as water is fresh?

 

Have any of you gone for a tank, to provide some redundancy as well as security of knowing you have a few hundred litres of water always available? 

 

I could probably put a alarm or sender on the tank, to warn if pressure or water level dropped. (Potentially even integrating it into Home Assistant)

[JohnMo]

Your other option 

28 minutes ago, Kuro507 said:

There a a metal storage vessel with a large rubber bladder in it,

This is an accumulator, there.will be a no return valve, between the pump and it. So even without pump on it remains pressurised. So your other option is to replace this with a bigger or several bigger ones. You have a pressure maintained water supply for normal use, it passes through your filter system as normal. Pump fails nothing changes you continue to get filtered water. You could add an alarm - if pressure remains at or below 2.9bar for x minutes send a notification to your phone.

[Kuro507]

1 hour ago, JohnMo said:

Your other option 

This is an accumulator, there.will be a no return valve, between the pump and it. So even without pump on it remains pressurised. So your other option is to replace this with a bigger or several bigger ones. You have a pressure maintained water supply for normal use, it passes through your filter system as normal. Pump fails nothing changes you continue to get filtered water. You could add an alarm - if pressure remains at or below 2.9bar for x minutes send a notification to your phone.

Yes, this would probably be the easiest option as I assume it reduces the risk of having stagnant water stored. Plumbing it would be simple, as a like for like swap. Would need to find a sensibly priced pressure sensor for monitoring. 

[JohnMo]

1 hour ago, Kuro507 said:

Would need to find a sensibly priced pressure sensor for monitoring

Over your existing pressure switch, add a shelly relay or similar, add a time based automation, it will normally takes 5 mins or less to reset, just set an hour or two automation, that if the switch hasn't reset in a hour raise an alarm.