I have an 800 sq foot barndominium with the water supply set up per the schematic when we bought it 5 years ago. Shortly after buying the property, the well head was destroyed and so we now fill the cistern with city of Austin water periodically. Another well is not an option for us.

Original pump was a DAB cast iron pump that I do not know the details of. It worked well through the first spring, summer and fall taking water directly from the cistern. I stupidly let it freeze without draining and it cracked the pump.

I bought a newer version DAB pump (DAB Shallow Well Jet Pump, 1HP, 1080GPH, 1 In. Ports, 110/220V, Model JETCOM 102M). Upon receipt the plumber noted this did not come with a pressure switch so I returned it.

Then tried to go for a pump with included switch and ended up with a cheap Everbilt or HP shallow well pump. This was installed by a handyman type plumber and worked well for a short time. PVC connections began to loosen after some time and I ended up with a leak. We thought it was from vibration from pump so he redid the plumbing and secured it down better, did a test check and looked good. Next time I went out it worked for about 30 minutes and then I went out and it was HOT and all PVC connections were eroded. Another leak.

Thinking it was a bad cheap pump and maybe a not so experienced plumber so I hired a reputable plumber in the area and bought a more expensive pump. Grundfos JP 16-10-187 1-Stage Shallow Well Jet Pump, Stainless Steel (115/230V, 1 HP). Upon install, the pump would cycle on and off rapidly so the thought was it was a defective switch on the pump. We also checked the pressure tank and realized it wasn't holding pressure so we replaced the pressure tank with an 80g (same size as before).
Finally got the replacement pump installed and guess what. Now it will run constantly and not shut off. He obviously shut it down. The plumber is at a loss and so am I. This seems like a really easy system set up for water from point A to B.

Please help!! Is this the wrong type of pump for the application? Does it matter that the empty well connection PVC is still attached to the cistern? Does it sound electrical (it is 240V and installed as such).

Hoping someone with experience can offer suggestions and even better if you live around Bastrop/Smithville