Leak worsens when water pressure high

Quick Answer:

If a drip at an outdoor spigot increases when the system sees higher pressure (for example when a pump starts or an appliance runs), measure the pressure and test the regulator and faucet before guessing. Attach a pressure gauge to the outdoor faucet and record both the static (no flow) and running pressure. If pressure spikes above normal household limits or the regulator doesn’t respond, lower the pressure temporarily to confirm the cause and replace a failed PRV or the hose-bib seals if tests show they’re the source.

Why This Happens

When system pressure rises, weak points in the plumbing see more force. A hose bib with worn seals or a failed packing nut will leak more under higher psi. A pressure-reducing valve (PRV) that’s stuck, set too high, or failing won’t hold the desired setpoint, so pressure events make the leak worse. Temporary spikes (pump cycling, sprinkler zones coming on, or thermal expansion) can push pressure above normal and reveal these faults.

If you’re watching the leak while appliances or pump cycles happen, and you see the drip worsen only during those times, you could be looking at a failing PRV or a faucet that passes under higher pressure. For more on the faucet side, see Hose bib leaks under pressure. For leaks that appear after pressure shifts in the system, see Leak after pressure change.

Step-by-Step What to Do

Gather basic tools

Threaded pressure gauge (hose-thread) or compressor gauge with adapter
Adjustable wrench and pliers
Temporary pressure reducer or a shower head with a shutoff (to reduce flow) if you want a quick test
Replacement seals or packing for the hose bib if needed

1. Measure static pressure at the outdoor faucet

Turn off all water inside and outside the house so no fixtures are running.
Attach the pressure gauge to the outdoor spigot and record the reading—this is the static pressure.
Write it down. Typical target range for many homes is roughly 40–60 psi; consistently higher readings indicate a problem.

2. Measure running (dynamic) pressure

Open a large indoor fixture (washer cold fill, or a different outdoor faucet) to create flow, then re-check the gauge at the spigot. This shows running pressure under load.
Compare static and running numbers. A big jump when something else runs, or very high static readings, points to a regulator failure or unusually high supply pressure.

3. Test the house PRV for setpoint and response

Locate the PRV (usually where the main water line enters the home). Note the setpoint if readable or manufacturer markings.
If safe and accessible, have someone open and close a large fixture while you watch the gauge to see if the PRV holds pressure steady. A healthy PRV keeps pressure near its setpoint; a failing one will let pressure rise or fluctuate.
If you’re comfortable, you can slightly adjust the PRV per manufacturer instructions and observe the gauge. If unsure, skip adjustments and call a pro.

4. Temporarily reduce pressure or flow to confirm the cause

As a quick test, reduce flow from a shower head or use a temporary inline pressure reducer to slow the pressure surge. If the drip at the spigot stops or greatly reduces when system pressure/flow is limited, that confirms the leak is pressure-sensitive.
Note that reducing flow can change how pressure behaves; use this only as a diagnostic step, not a permanent fix.

5. Replace seals or the PRV if tests confirm failure

If the hose bib leaks only under higher pressure and seals or packing appear worn, replace the internal washer/packing or the entire bib. This often fixes faucet leaks exposed by higher psi.
If pressure tests show the PRV isn’t holding the setpoint or pressure is regularly above recommended limits, replace the PRV. A malfunctioning PRV can damage fixtures and lead to repeated leaks.
After replacement, re-test static and running pressure to confirm the issue is resolved.

What Not to Do

Don’t assume tightening the bib will cure pressure-related failures or keep adding washers; these are temporary or cosmetic fixes when pressure is the root cause.
Don’t ignore high pressure readings—call a pro when pressure tests show readings above recommended limits or when leaks persist only under higher psi.
Don’t disable or bypass a PRV as a quick fix. That can expose the whole house to damaging high pressure.

When to Call a Professional

If static pressure is consistently above recommended household levels (commonly above about 60–80 psi depending on local guidance), call a plumber to inspect and likely replace the PRV.
If the PRV appears to be working intermittently or you can’t access or identify the device, get a pro to test and replace it safely.
If you’re uncomfortable replacing faucet seals or working on the main regulator, a licensed plumber will diagnose and fix the problem without risking damage.

Safety Notes

Shut off the main water before doing any repairs on the PRV or replacing a hose bib to avoid water damage.
Relieve pressure by opening a faucet after shutoff before disassembling parts.
Use eye protection when working with pressurized fittings. If you suspect extreme pressure or a burst pipe, leave the area and call a professional immediately.

Common Homeowner Questions

What pressure is safe for a house?
Most homes aim for about 40–60 psi; anything consistently higher should be evaluated.
Can I test the PRV myself?
You can measure static and running pressure with a gauge; adjusting or replacing a PRV is best left to someone experienced if you’re unsure.
Will replacing a washer fix a pressure-related leak?
Sometimes for a simple faucet leak, yes. But if the leak only appears under higher pressure, first confirm and correct the pressure source.