My house has city water for the internal water, and a well system for the external hose bibs. It consists of a (approx) 40 gallon galvanized tank, a 1/2hp sears pump that is bolted on to the well pipe, and a 40/20 pressure switch.

I was having some problems with low pressure, unable to run a sprinkler on the hose for very long without losing pressure. To note - the system does hold pressure when not in use. So, I did a few things:

-Dewaterlogged the tank - I installed a schrader valve on the tank, drained it, precharged with 18psi air, and let it fill back up. I also installed a new air control valve.

This seemed to help. Problem is though, when I ran my sprinkler, it worked until one day I heard all my 'precharge' air come hissing out the hose.. the pump cannot keep up with the hose and I lost the air charge.

I tried installed a 50/30 switch to get a little more pressure, but.. the pump simply will not make more than 46psi. I have no idea what diameter the well is, how deep it is, etc. All I know is that the pump is bolted to the surface pipe in my basement - so I believe its a shallow pump. Problem is, my neighbor also has a well, and he says that his is about 80 feet deep. This makes no sense - I thought shallow pumps were only good to 25 ft.

I am looking at the prospect of doing two things:
1) Buying as large of a bladder tank as will fit in the space - this should improve my drawdown capability.
2) Buying a new pump - the pump looks like an original. Its 115V. I believe I can get a new 1/2hp pump that should help.

Again, the only use of this system is to feed my outside hose hookups. Thats it. I would REALLY like to have adequate pressure out there - I can't really even water my lawn right now. It starts out at 40 psi and rapidly drops to 20. At 20psi, my sprinklers are next to worthless.

As a stopgap measure - what type of sprinkler (hose) is suitable for a low-pressure system? I really need to get some h2o on my sad grass.

One last question - How does one determine the GPM that the well can supply? Before I buy all this stuff, I want to make sure I dont have a slow-flowing well. That would require perhaps a different solution.