Hi everyone. I need some guidance on how to correctly share a borehole system with my neighbour.

My neighbour has a borehole with a submersible pump that is controlled by the float switch in his tank. He then has a booster pump from the tank for irrigation and also connected to his house as a mains backup.

(With his permission) a plumber recently added a T-junction on the pipe coming from the borehole before it reaches his tank. One branch goes to his tank as normal and the other goes to my new tank. I also have my own booster pump for outdoor taps and back up for my house. My tank has a ball valve.

The way the plumber connected everything does not work (which he has admitted). My tank only receives water when his tank water level goes low and the float switch triggers the borehole pump to switch on. My tank cannot trigger the borehole pump at all. And the t-junction sends water in both directions regardless.

There are some solutions/quick fixes, but I do not want to connect our tanks together because his tank would constantly be filling and emptying in order to fill mine. I also do not want to connect my tank after his booster pump because that would make his booster run unnecessarily to fill my tank and may reduce his water pressure if on back up to mains.

What I am looking for is the correct way for my tank to also trigger the borehole pump when it is low and also for both tanks to fill independently without risk of overflowing. I am hoping for a proper electrical or control solution. If possible, it would also be ideal for my electricity supply to run the borehole pump when my tank needs to refill.

If anyone has experience with sharing a borehole pump between two separate tanks and households, I would really appreciate recommendations.

Edited November 16, 2025Nov 16 by ZFM

You would have to put a level switch in your tank as well and put it in series with his one

Then he would also need a ball valve in his tank

Then if either of the level switches put on the borehole both ball valves will still be open and will receive water till the full one closes its ball valve and the other tank will fill till the level switch in the empty tank puts off the pump again and that ones ball valve will still be open

You would have to make sure both ball valves only close when the level switches are already off, that way if one level switch triggers the pump both would fill up till the ball valve in the full tank will switch off the flow of water to that tank and continue to fill the other tank that is empty

What you must also do is use some sort of relay to make the level switches only switch on the pump when the the line is open and switch off the pump when the the level switch line in closed

Hi

Would it not be a simpler solution to have a third elevated tank which is above the level of the existing 2 tanks used as a control tank to feed both tanks?

Each of the two tanks each have a ball valve to prevent overflow and the switch that controls the pump installed in the elevated tank.

That way you also have added capacity.

Cheers