Why is my well pump running but not building pressure?

The most common causes are a failed pressure switch, a waterlogged pressure tank, a leak in the system, a worn pump impeller, or a drop in well water level. Check the pressure switch contacts and pressure tank first as these are the easiest DIY fixes.

How do I know if my well pump is failing?

Signs of a failing pump include: pump runs but pressure never reaches cut-out, pump hums but water flow is weak, pump cycles rapidly, or pressure drops suddenly during use. A pump that runs continuously without building pressure usually has a mechanical failure.

Can low well water level cause pressure problems?

Yes. If your well yield has dropped due to drought or seasonal changes, the pump may be drawing air or running dry. Signs include sputtering water, gurgling sounds, and pressure that builds slowly then collapses.

TROUBLESHOOTING GUIDE 9 min read · Updated 2025

Well Pump Not Building Pressure — 7 Causes & Fixes

Your pump is running but pressure never reaches cut-out — or pressure builds slowly then collapses the moment you open a tap. This guide covers every common cause, from a $15 fix to knowing when you need a professional.

In This Article

Failed or stuck pressure switch
Waterlogged pressure tank
System leak
Worn pump impeller
Low well water level
Clogged intake screen
Failing pump motor

🔍

Start here: Before diagnosing, note whether pressure builds at all or never moves. If the gauge reads 0 and never moves, start with Cause 1. If pressure builds slowly or collapses under demand, start with Cause 3 or 4.

✅ DIY — Easy

1. Failed or Stuck Pressure Switch

The pressure switch tells the pump when to stop. If its contacts are stuck open, the pump gets no power. If they are welded shut, the pump runs continuously. A faulty switch is the first thing to check — it costs $15–30 to replace.

Diagnosis: With pump running, check if the pressure gauge moves at all. If gauge reads 0 and never moves, the switch may not be sending power. Check for power at the switch terminals with a multimeter. Look inside the switch for burnt or corroded contacts.

Fix: Tap the switch lightly — stuck contacts sometimes free up temporarily. If contacts are burnt, replace the switch. Match the amperage rating on the label (usually 20A or 30A).

✅ DIY — Easy

2. Waterlogged Pressure Tank

A waterlogged tank has no air cushion — every drop drawn causes an immediate pressure drop. The pump cycles constantly but pressure never feels stable. This is the most common cause of "pump runs but pressure is weak."

Diagnosis: Press the Schrader valve on top of the tank with pump off and pressure released. Water out = waterlogged. Air out = check pre-charge pressure with tire gauge.

Fix: If air comes out but pressure is low, recharge to cut-in minus 2 PSI. If water comes out, replace the tank. Use our calculator to size the replacement correctly.

✅ DIY — Moderate

3. System Leak

A leak anywhere between the pump and your faucets bleeds off pressure as fast as the pump builds it. Underground leaks are silent but can waste hundreds of gallons per day while keeping pressure perpetually low.

Diagnosis: Turn off all water in the house. If the pump still cycles, you have a leak. Check all visible pipes and fittings for drips. Listen for hissing near the pressure tank and supply lines. Check your water meter — if it moves with everything off, the leak is underground.

Fix: Visible leaks — tighten fittings or replace pipe sections. Underground leaks — call a plumber. A leak detection dye can help locate the source.

⚠️ Moderate

4. Worn Pump Impeller

The impeller spins inside the pump to move water. Over time it wears down — especially if the pump has been running dry or pumping sandy water. A worn impeller reduces flow significantly but the pump still runs, giving the appearance of "low pressure."

Diagnosis: Measure actual flow at a tap with a bucket and timer. Compare to your pump's rated GPM. If flow is 30% or more below rated, suspect the impeller. Also check for sand or grit at faucet aerators.

Fix: For submersible pumps, the pump must be pulled from the well — a job for a well contractor. For jet pumps, impellers can sometimes be replaced without pulling the pump.

⚠️ Moderate

5. Low Well Water Level

During drought, heavy use periods, or seasonal changes, your well's water table may drop below the pump intake. The pump draws air, pressure builds then collapses, and you may hear gurgling or sputtering at faucets.

Diagnosis: Pressure builds normally when the pump first starts but drops suddenly after a few minutes of use — classic sign of low well yield. Check with neighbors on the same aquifer.

Fix: Let the well recover — turn off the pump for 30–60 minutes and see if pressure normalizes. Long term: install a well storage tank, have the well deepened, or install a variable speed pump controller that reduces pump speed as water level drops.

✅ DIY — Easy

6. Clogged Intake Screen or Filter

Submersible pumps have a screen that filters sediment before it enters the pump. A partially clogged screen reduces flow and pressure. Whole-house sediment filters can also become clogged and restrict flow severely.

Diagnosis: Check any whole-house filter housings — a dirty filter cartridge is obvious visually. Bypass the filter temporarily and see if pressure improves. For submersible intake screens, the pump must be pulled.

Fix: Replace filter cartridges every 3–6 months depending on sediment load. For intake screens, a well contractor can pull and clean or replace the screen.

🔴 Call a Pro

7. Failing Pump Motor

A pump motor in its final stages often runs — you can hear the hum — but produces little or no water movement. The motor windings are breaking down, usually from years of short-cycling, overheating, or running dry.

Diagnosis: Pump hums or buzzes but pressure gauge does not move at all. Check amp draw at the breaker with a clamp meter — a failing motor often draws more current than rated (overload) or less (open winding).

Fix: For submersible pumps, motor replacement requires pulling the pump — a well contractor job averaging $800–1,500. Sometimes it is more cost-effective to replace the entire pump assembly. Get two quotes.

Quick Diagnosis Reference

Symptom	Most Likely Cause	DIY?
Gauge reads 0, never moves	Bad pressure switch	✅ Yes
Pump cycles every few seconds	Waterlogged tank	✅ Yes
Pressure drops when water runs	Leak or low well yield	⚠️ Maybe
Weak flow at all taps	Worn impeller or clogged filter	⚠️ Maybe
Pressure builds then collapses	Low well level	⚠️ Monitor
Pump hums, no water movement	Failing motor	🔴 Call pro
Sputtering air at taps	Low well level or bad tank	⚠️ Diagnose first

Is Your Pressure Tank the Right Size?

An undersized tank is one of the most overlooked causes of ongoing pressure problems. Our free calculator sizes your tank correctly based on your pump and pressure switch settings.

→ Calculate My Tank Size — Free