I also have this problem but don't have a inline filter. There is a big tank with an airvalve like you describe, but it feels empty when I shake it. Then there is an iron removal tank and the water softener. The gauge is reading 18psi right now and pressure in the entire house is affected. I set the softener on backwash, and while it was discharging, the pressure does not improve. I also turned the power on and off to the pump, no change.

I had the same scenario happen this week. Following is how my system is setup:

1. Well with a submersible pump, about 200 feet from the house
2. 40/60 pressure switch that appears to be cutting off at 58 psi, and coming on around 32-34psi
3. 20 gallon pressure tank set according to manufacturer's specifications
4. 100 micron filter (manual backflush which I do often)
5. 5 micron filter (I change this regularly as it is needed.)

I noticed tonight that the pump cuts off at 58psi, and within seconds drops to 50-52psi without any water running. It stops at 50-52psi and doesn't go any lower. I also noted that when the pressure drops to about 38-40, the pressure stops dropping for a bit, then drops to 34 and the pump kicks on. The pressure gauge on the 100 micron filter shows 3.5psi with no water running. I'm assuming this is pressure loss across the filter. I don't know what the loss is across the 5 micron filter. Even when the system was working correctly I had issues with the top rack in the dishwasher.

I'm pulling my hair out trying to figure out what is wrong. One thing I'm doing is to replace the small diameter filters and installing a larger diameter filter to reduce pressure loss. The 100 micron doesn't catch a lot, so really all it does for me is to reduce the available pressure.

Any ideas?

Thanks,
Jeff


One additional thing is that there is no water escaping from the tank when I depress the air valve, so I don't suspect that the tank is ruptured.

Another question, is it possible for the line to have a crack that only leaks when the pressure is >50psi?

When your system is losing pressure when no water is being used, it is generally due to a faulty/leaking checkvalve.