Why will my well pressure not go above 40 PSI even when I hold the pressure switch closed?

Question

My well is probably 200' deep and is about 50' from the house. I have no idea what the pump HP is.

I have tried different pressure switches and adjusted them up / down but I can never get more than 42 psi, so I have the switch set at 20 / 40. If I hold the pressure switch closed for as long as 15 minutes it still will not pump beyond 42 psi. I would really like to have 30/50 psi. I now have the bladder tank set to 18 psi for 20/40 pressure setting. In order to get 30/50 do I need a larger well pump?

(If I install a 30/50 switch the current pump never shuts off.)

Answer 1

You need a pump that will provide more pressure. That may or may not be "larger" in terms of HP - my recollection was that the most common 1/2 HP submersible pumps when I was shopping were actually set up for higher pressure/deeper wells than the 3/4 HP pump I got, but the key is that the HP alone does NOT tell you what the pump can or will do - different impeller/staging setup can do more volume at lower pressure or more pressure at lower volume from the same HP input. This is seen by comparing "pump curves" which is what truly matters when choosing the right pump.

You can make some slight inference as to pump HP from the size of the breaker (or fuse) on the pump circuit, but given the starting surge it's not entirely definitive.

My particular 3/4 HP pump works just fine (set at 40/60) from 300 feet down more than 100 feet from the house, and will draw the well from 100 feet down all the way to the pump location (my well drillers appear to have fibbed quite a bit about the GPM my well produces, since it was chosen with their numbers and the well should not draw down to pump level if their numbers were correct.)

Another possibility is that your pump impeller may have worn to the point that it no longer works as designed, and it's possible that a pump of the same power and impeller setup that was new should work fine.

When you get a new pump, be sure to stick the provided labels (usually - or just write the information with a permanent marker) on the pump control box or breaker panel or on the wall near the pressure tank so that you or the next person will actually know what pump is down the well.

Answer 2

Wells are all so different. In my area, we have few aquifers, rather it's mostly underground rivers. So, as usual, "it depends" (sorry!) Water deep down can be under a lot of pressure so when the driller finally hits water, it can rise a lot in the well casing. At my parent's farm there is a 150' well in which the water rises over the top of the well casing when the pump isn't on.

For your issue: like @ecnerwal said, your pump may be worn out. That happens. If not, to properly size a replacement pump, you need to know what the well's production is, the static water level and the draw down level while pumping a known volume of water. Fairly technical stuff and easy to screw up. If you put too large a pump in for the well's production capacity, you'll be "sucking air" and that's very hard on pumps. BC this is a DIY site, I hate to recommend it, but you may need to bring in a good "well/pump guy" to figure out whats going on.

My best guess, based upon what you said, is a worn out pump.

EDIT: I'm adding to my answer: There are lots of pump designs out there. Some are low horse power, high pressure but low volume. Some are the opposite. The most important part is to know the characteristics of the well and match the pump and/or pump system to it. Not an easy task for a DIYer, IMHO.

A friend mine, maybe only about 10 miles away, ended up with a very low producing well, on the order of 1-2 GPM. He ended up having to install a large, non-pressurized holding tank so he could get adequate flow for things like taking a shower, watering the lawn, etc. The well pump would keep slowly filling the holding tank and then an above ground pump (centrifugal) would pump from the holding tank to the pressure tank. Obviously fairly complex controls where needed so as not to draw down the well too much, or empty the holding tank. Sensors and floats where involved.

Hopefully your well produces enough water and all you have is a worn out pump, or maybe the wrong pump.

Answer 3

In my last house I had a 1/2 HP submersible pump that would only pump to 50 PSI. When the well guy drilled a new well, since the original well had too low capacity for our needs, he had to install a 3/4HP pump. The new well supplied all the water we needed and we could run it at 40/60 PSI. Since this well was deeper than the old well the 1/2HP pump would barely pump to 45PSI so a larger pump was needed for the pressure I wanted.

It is also possible that the pump needs to pulled from the well and the impellers or inlet screen cleaned. If the impellers get clogged with silt, sand, dirt, or clay, or anything, the pump looses capacity. This happens in my area a lot.