" wrote:

It's a submersible pump, but I'm in NC where below rainfall.....bty, I
noticed after a good rain my water was a little brownish for a day or
so.

If there is a noticeable change in the water after a rain that would be
a real good reason to get the water tested. They say you should test
wells at least annually anyway.

Would a loose clamp/leak cause it to suck air?

Possibly, but with a submersible it wouldn't cause a stop in water flow
like you indicate since the only plumbing on a submersible pump is on
the output (pressure) side. A slight leak at a fitting going in the
correct direction could let it do the venturi thing and suck in some air
as the water rushes past, but since it's after the pump it can't cause a
loss of prime. You would also notice the very obvious bursting /
sputtering of air in the water line when you're running the faucet.
Knocking of the pipes does not indicate air in the lines, it only
indicates pressure waves like from a pump startup or a valve closing.

I have over the years
found 2 leaks and they were repaired (in the pvc line from the pump to
the house). Also, I used to hear the pressure switch turn on and off
faintly in the bathroom, but I don't hear the same sound now.

Is the difference in sound since you replaced the switch, or just since
you began having the water problems? A new switch could certainly be
quieter than the old switch. If it's a recent occurrence with the new
switch it could indicate a problem with the switch causing it to not
trip solidly.

The switches are designed to "snap" between on and off states to
minimize arcing on the contacts. If it's not "snapping" it could be
arcing, burning the contacts and causing the pump to not start smoothly
or immediately when it should.

You really need to run the water while standing next to the
tank/pressure switch/pressure gauge to see exactly what is happening as
the storage tank is drawn down. There should be a drain connection near
the tank where you could hook a hose up to drain outside. You can start
with the tank "full" or at least at normal max pressure, open the drain
and watch and make notes of the pressure reading when you hear the
switch click, when you see the pressure start to rise again, etc.

Pete C.