Need recommendations on a water level switch in a cistern

[MillWeld]

When our garden finally gets underway it will place a demand on our cistern to supply water without pumping it dry and damaging the pump, so a switch to sense the water level is needed. The cistern is 5' deep and has an unused 1" PVC pipe going from the headspace in the cistern to the crawlspace and this is what I would use for running wire to a switch. This run of PVC has two 90 degree elbows and two 45 degree elbows and is probably less than 20 feet. It may be a challenge to run wire thru it but when (if) I undertake it I want input as to the kind if level switch to use: pressure sensing? a tilting or angle-dependent switch? or some other type? I have never installed such a switch before so most any kind of input is OK.
Bob

 

[lilranch2001]

float switch is probably the cheapest, but there are many more technologies out there that can do the job.
You do not mention how east the cistern is to access, and how easy it will be to mount the level switch
One of the ways I have fished wires through pipebesides with a fish tape is to blow a lightweight ball with a string attached through it, does the pvc have hard 90 degree turns or are they sweeps?

 

[dstig1]

Float switch would be the simplest

 

[Rock knocker]

Feed you pump thru a Normally Closed float switch in the tank. When the level drops too much, the float switch will tilt and interupt the pump circuit. The circuit will remain (electrically) open until the level rises enough

 

[MillWeld]

You do not mention how east the cistern is to access, and how easy it will be to mount the level switch
does the pvc have hard 90 degree turns or are they sweeps?

There is no way to mount it; it will have to dangle from a wire, so I guess that mean a float switch?
The ells are hard turns.

 

[lilranch2001]

There is no way to mount it; it will have to dangle from a wire, so I guess that mean a float switch?
The ells are hard turns.

what size PVC?

 

[Willl]

This style has been living in the non-sludge tank on my septic system for 15 years plus without fault.

Would think it's pretty robust.

 

[MillWeld]

This style has been living in the non-sludge tank on my septic system for 15 years plus without fault.

Would think it's pretty robust.

I found it on the web but no obvious place to order it. Where did you get it?

 

[Raspy]

If you can get through the tank wall you could put a probe sensor in and have no wires in the tank at all. The problem with float switches is how to control the overall height of the water. In other words, the level lowers until the switch makes contact, then the contact breaks when the water rises a bit, but not to the full level. One way to work around this is with a time delay relay that keep the pump running for an adjustable amount of time after the float switch rises and opens the circuit. They are easy to install and completely adjustable with a knob.

This way you can put the float switch near the bottom and still fill the tank completely. And do it all with one float switch and no wires in the tank.

This is the setup I'm putting in my water tank for my house. The water level system will turn on the well pump to fill the storage tank. I'll adjust the time delay to get the tank near full.

You can also use this system on the pressure side feeding the house to protect the pressure pump if the tank ever does go dry. The delay relay will limit the time the pressure pump can run on each cycle. If the tank runs out of water the system will lock out until you fix the problem.

 

[MillWeld]

The tank is plastic, completely buried but with an access lid at grade. It captures rainwater and overfilling is no problem because it has a 6inch spill pipe. The only reasonable access for wiring is the 1" PVC pipe. I think all I need is a SPST switch to shut off power to the pump at some minimum water level.