On Monday, June 12, 2017 at 1:09:39 PM UTC-4, MarkK wrote:
Hi All,

Put in a new well but the tank is getting waterlogged once a month. A
plumbing supple pro tells me that I need to drill a 3/16" hole in the
drop pipe (below ground) so that a slug of air will be delivered to the
tank every time the pump turns on. A check valve was installed directly
above the submersible pump and a second check value was installed between
the well cap and the tank.

Does drilling a hole in the drop pipe make sense to you?

You don't tell us about the tank, is it new too?
If so, that tank should have a bladder that holds a charge of air
that is set based on the operating pressure range. Once the air
is in, unless the air valve or bladder is leaking, the tank won't
get water logged. The older style tanks from decades ago didn't
have an air bladder. Instead they relied on keeping an appropriate
volume of air in the tank by a valve gizmo that was installed in
the tank near the middle and had a line running back to the suction
side of the pump. If the air level got low, the mechanism would
allow the pump to suck some ambient air, thereby replenishing the
air in the tank. That was with a pump at the tank and the simpler
system.

In the case of submersibles with old tanks, they used a bleeder
orifice located on the suction pipe inside the well, below grade.
This was another check valve type device that let's water out,
but not in. There was a check valve at the tank which also
had a schrader air valve on the well side. When the pump shuts
off, there is no pressure in the pipe, so the orifice opens and
air enters via the schrader valve at the tank check valve.
The section of pipe between tank and orifice winds up filled
with air. Next time the pump starts, that air goes into the tank.

Next problem is that it's always putting air in, which would lead
to too much air. So there was some other contraption installed
about half way up the tank that had a float and if there was too
much air, it would allow it to escape. All that of course was
replaced by the bladder type tank for obvious reasons. So, if
you have the older no bladder type, you need to install one of
those bleeder orifices in the line inside the well. And make
sure you have the rest of the system.