Plumbing and wiring a cistern

grover · April 15, 2015, 01:53:01 PM

Can anyone help with the plumbing and wiring of an underground cistern?

I have a concrete cisern of around 1500 gallons installed. It has a hatch on top for inside access and there is a threaded fitting on the side a couple of feet down from the surface. I think this fitting is where the water will come out of the tank and to my water line. I think I want to use a submersible pump that puts out 7-10 gallons per minute. I know I have to plumb the water from the cistern to a storage/pressure tank. I think I can put this tank in the crawl space but if it needs to be in the cabin I can probably manage that too.

Any website you can recommend to help me or if someone out there has done this and documented the process that would be helpful.

hpinson · April 15, 2015, 05:54:30 PM

[Edited per comments]

There are many ways to do this based on your situation. Here's an example:

Assuming the cistern is a) gravity filled by rainwater or by a spring, b) not terribly different from height from your house; you might look at a jet pump system rather than a submersible. These pumps are very inexpensive. These work well so long as there is minimal lift involved between tank and house, though the run can be significant.

The supply chain goes more or less like this:

Cistern > foot valve > pipe out of cistern > shutoff > check valve > tap (for collecting water samples and drainage) > properly sized pipe run > inside house > jet pump > pump pressure gauge > properly sized pipe run > water filter > properly sized pipe run > house pressure gauge (35-60 PSI) > relief valve / tap > house distribution storage tank > float switch in tank to turn pump on and off at certain storage threshold > house distribution <> bladder type pressure tank

The size of the pump would be determined by the amount of uphill pushing it would need to do (depends on pump but say 6' max

), the run, and the flow rate you require. Downhill is better.

Google and you should be able to find some diagrams of this. Pump supply houses can be very helpful in sizing and even in helping you design a small system, especially if you will give them business.

Having a well changes this a bit it that in addition you need a submersible pump in the well.

Maybe you could provide more specifics of your situation?

Water source for cistern?

Height difference between cistern and house?

Run between cistern and house?

AC, DC or gravity powered?

April 15, 2015, 07:15:28 PM

Quote from: grover on April 15, 2015, 01:53:01 PM
I know I have to plumb the water from the cistern to a storage/pressure tank.

The storage portion causes some slight confusion to me..... Is the idea to have a pressure pump / system that is separate from the cistern pump? Or to use the one pump to move water from the cistern and to supply pressurized water throughout the cabin fixtures?

We use a separate indoor supply tank but that was because we leave the cabin vacant through freezing weather and doing that makes winterizing easier.

DaveOrr · April 15, 2015, 08:09:23 PM

Quote from: hpinson on April 15, 2015, 05:54:30 PM
There are many ways to do this based on your situation. Here's an example:

Assuming the cistern is a) gravity filled by rainwater or by a spring, b) not terribly different from height from your house; you might look at a jet pump system rather than a submersible. These pumps are very inexpensive. These work well so long as there is minimal lift involved between tank and house, though the run can be significant.

The supply chain goes more or less like this:

Cistern > pipe out of cistern > shutoff > check valve > tap (for collecting water samples and drainage) > properly sized pipe run > jet pump > pump pressure gauge > properly sized pipe run > water filter > properly sized pipe run > house pressure gauge (35-60 PSI) > relief valve / tap > house distribution storage tank > float switch in tank to turn pump on and off at certain storage threshold > house distribution <> bladder type pressure tank

The size of the pump would be determined by the amount of uphill pushing it would need to do (depends on pump but say 20-30ft max), the run, and the flow rate you require.

Google and you should be able to find some diagrams of this. Pump supply houses can be very helpful in sizing and even in helping you design a small system, especially if you will give them business.

Having a well changes this a bit it that in addition you need a submersible pump in the well.

Maybe you could provide more specifics of your situation?

Water source for cistern?

Height difference between cistern and house?

Run between cistern and house?

AC, DC or gravity powered?

Don't forget the foot valve in the tank.

hpinson · April 15, 2015, 08:32:08 PM

If I remember, the DC Shurflo jet pumps deliver/ push water out pressurized, AC jet pumps probably do the same. The two cabin water systems I'm familiar with have storage before the jet pump and dispense with the pressure tank altogether - the water pressure is generated by the pump and flows pressurized to the hot water heater and then out to the kitchen tap and bathroom. Pretty unclear on that though - it seems a primitive but workable system.

Maybe someone else could expand...

April 15, 2015, 11:09:50 PM

The system at my house has a combo jet pump/pressure tank mounted on top of my 500gal water tank. It is connected to a supply pipe that runs down into the tank that has a foot valve on the end to keep prime.

The pump is like this one (110volt)
http://www.canadiantire.ca/en/pdp/mastercraft-convertible-5-gallon-jet-pump-1-2-hp-0623588p.html#.VS81sfnF8iY

Don't see why you couldn't stick a pressure tank into a low voltage pump system if needed.

rick91351 · April 16, 2015, 07:47:34 AM

Grover this is what we did.

grover · April 16, 2015, 03:50:18 PM

I'll try to answer some questions.
The cistern is mostly underground, just the top is above ground. The concrete top was put on with a rope looking gasket that looked to be soaked with a tar like substance. That would be the only thing keeping mud and silt out if I covered it up with dirt. I was afraid it might leak around the seal so that's why it is not completely covered. The bottom of the cistern is probably about 4-5 ft below the crawl space level which is where I'd like to put the pressure tank. If I bring the pressure tank up into the cabin it's about another 3 ft so that would put it at 7-8 ft vertical difference. The pipe from the cistern to the tank would be approximately 30 ft. I'm not sure the size of the fitting on the side of the cistern. I'm hoping it is at least an 1 or 1 1/4 inch. The water will be hauled in for now but I would like to hook it up to the gutters if I can do that and have safe drinking water. I have public utility electrical service so power will be AC.

To sum up;
One pump Don. Either a submersible in the cistern or a jet pump in the crawl. I don't know of a need for another.
AC power
Lift of no more than 8ft.
Run of about 30 ft.
Supply line size to be determined.

Does the fitting size on the cistern limit the flow? For instance if the fitting is 1 inch then is a 1 inch supply line the biggest that I should use?