Hey guys,

My dad and I have a perplexing water problem that we can't reason out.
Hoping there's some detective out there...

We have a shallow well and a jet pump, about 20m head to the house, a
pressure tank and pressure switch in the house. System had been
working great for 15+ years (same pump and tank too!), pressure switch
is set from 30-45psi.

Here's the problem: Starting with a full pressure tank, we turn on
some taps, water flows at a good pressure, the pressure gauge needle
falls slowly as is expected. When the water pressure gets down to 30,
the pressure switch makes an audible click but then instead of water
rushing in and pressure going back up, the pressure falls fast to
about 10psi and continues to trickle out the taps for hours. The
pressure does not go up until we turn off all the taps. Once this is
done, the pressure goes up fast again to 45psi and the cycle repeats.

??

The pump seems strong since it can pressure up fast to 45. The
pressure switch (which we replaced brand new with no effect) is
clicking at the right times.

Why would pressure fall fast at 30psi after the switch clicks? Why
would the pump only start back up when all the taps are closed?

Any suggestions would very appreciated!!
Thanks