Sudden drop in water pressure across the house? Pressure that's been creeping down for years? Different fixtures, different pressures? Each tells us something different. Here's the diagnostic our crew runs through, in order of how common each cause is.
First: confirm the pressure
A pressure gauge on any hose bib costs $12 and tells you everything. Screw it on, open the bib, read the static pressure.
- Below 40 psi: low. Find the cause.
- 40–60 psi: normal range.
- 60–80 psi: ideal.
- Above 80 psi: too high — needs a PRV (pressure reducing valve).
If you don't own a gauge, your municipal water department can usually tell you the street pressure for your zip.
Cause 1: Failing PRV (pressure reducing valve)
The most common cause of gradual pressure loss in DFW. PRVs typically last 7–12 years. When they fail, they slowly drift toward closed.
Diagnosis: pressure at every fixture is uniformly low. House is post-1990 (almost all have PRVs).
Fix: replace the PRV. $300–$600 installed. We can sometimes adjust an old one back into spec, but a 10-year-old PRV is on borrowed time.
Cause 2: Clogged aerators (single-fixture issue)
If pressure is low at one fixture but fine elsewhere, it's the aerator — the screen at the tip of the faucet.
Fix: unscrew the aerator (most twist off by hand or with pliers), soak in white vinegar overnight, scrub the screen, screw back on. Free.
Cause 3: Mineral buildup in supply lines
Older galvanized supply lines accumulate mineral scale that narrows the bore. By 50 years old, a 1/2" galvanized line might effectively be 3/8" or smaller.
Diagnosis: house has galvanized supply (built before ~1965), pressure is uniformly low, replacing PRV doesn't help.
Fix: repipe with PEX or copper. $4,000–$12,000 depending on house size.
Cause 4: Partially closed shutoff valve
Easy to overlook. A main shutoff that's been knocked or partially closed restricts flow.
Fix: walk the line from the meter to the house. Check the curb stop, the inside main, and any meter-side valve. All should be fully open.
Cause 5: Slab leak diverting water
A slab leak takes water away from your fixtures and dumps it underground. You may also see a high water bill or a spinning meter with everything off.
Fix: see our slab leak symptoms guide. Detection then repair.
Cause 6: Pressure from the street is low
Sometimes the street pressure itself drops — utility work, peak demand, distance from the pumping station.
Diagnosis: pressure varies significantly by time of day; neighbors have the same complaint.
Fix: a booster pump system ($1,500–$4,000 installed). Worth it for chronic low-street-pressure situations.
Cause 7: Failed water heater dip tube (hot-water side only)
If pressure is fine on cold but weak on hot, the dip tube inside the water heater may have broken off and be partially blocking the hot-water outlet.
Fix: replace the dip tube ($25 part, 30-min job) — or just plan a water heater replacement if the unit is older than 8 years.
Quick decision tree
- One fixture? → Aerator or fixture-specific shutoff.
- All fixtures, gradual decline? → PRV failing.
- All fixtures, sudden? → Closed valve, broken main, or street issue.
- Hot only? → Dip tube or water heater issue.
- Spike in water bill? → Slab leak.
When to call a plumber
We carry pressure gauges, PRV kits, and PEX in the truck — most pressure calls are handled in one visit. Call us.
