Low pressure on a private well has a manageable list of causes, and a gauge and fifteen minutes narrows it quickly.
First: everywhere, or one fixture
One fixture — a blocked aerator, a partly closed stop, a failed cartridge, or a corroded supply line. Local, and nothing to do with the well.
Everywhere — the system. Continue below.
Check the gauge
Watch the pressure gauge at the pressure tank through a full cycle.
Where does it cut in and cut out? Common settings are 30/50 and 40/60 psi. A switch set to 30/50 in a house that wants more pressure is simply set low, and raising it is possible within the pump's capability — with the tank precharge reset to match.
Does the pressure fall smoothly from cut-out to cut-in? It should take a reasonable time. An instant drop means the tank is delivering almost no drawdown.
Does the pump short cycle? Starting and stopping repeatedly during one draw is the classic waterlogged-tank symptom.
The pressure tank
Tap it. Hollow at the top, solid at the bottom, with a clear transition. Solid throughout means it is waterlogged.
Press the air valve. Air is correct. Water means the bladder has failed and the tank needs replacing.
Check the precharge, with the pump off and the tank drained: it should be 2 psi below cut-in.
Wrong precharge is the most common cause of both short cycling and poor pressure, and it is a fifteen-minute fix.
Filters and treatment
A clogged sediment filter is one of the most common causes of gradually falling pressure, and it is the cheapest to fix.
Any treatment vessel — softener, iron filter, carbon — adds pressure drop, and a fouled one adds a great deal.
Test by bypassing each in turn. If pressure returns with a unit in bypass, that unit is the restriction.
The pressure switch
Contacts pit and corrode with age, and the small tube feeding the switch clogs with iron or sediment.
A switch reading a blocked tube sees the wrong pressure and behaves accordingly. Clearing the tube is a small job.
The pump and the well
Air spitting from taps means the pump is drawing air — the well level has reached the intake, or there is a leak in the drop pipe, or the check valve has failed.
Pressure falling over the summer and recovering in spring points at a seasonal water level rather than equipment.
A pump that runs continuously without reaching cut-out is either failing, or the well cannot supply what is being drawn.
Each of these is a well contractor's diagnosis, made with an amp reading and a level measurement before anything is pulled.
Pipes
Old galvanised pipe narrows internally with corrosion over decades, and the restriction is real and progressive.
A partly closed valve somewhere after work, which is worth checking before anything else is bought.
The order to check
Gauge and cut-in setting. Tank precharge and bladder. Filters, by bypass. Pressure switch and its tube. Then the pump and the well.
The first four cost nothing and account for most cases. The last one is the expensive answer and it is the one people start with.
Pressure and flow are different complaints
Pressure is the force at the tap, in psi. Flow is the volume delivered, in gallons per minute.
A house can have good pressure at one tap and run out of flow when three run at once — that is a supply or a pipe-size problem, not a pressure switch setting.
Distinguishing them changes what to look at: pressure points at the switch and the tank, and flow points at the pump, the well, the pipe size or a restriction.
Constant pressure systems
A variable-speed controller holds a steady pressure regardless of demand, rather than cycling between two setpoints.
It removes the pressure sag as fixtures are added, starts the pump gently, and needs only a small tank. It is a retrofit on many existing submersible installations and it is the standard answer where the complaint is pressure that varies rather than pressure that is low.