Quick answer
Start by measuring your water pressure with a gauge at an outdoor hose bib. Ideal household pressure is about 50–60 psi. If pressure is low, work through the simple fixes first: fully open shutoff valves, clean faucet aerators and showerheads, replace clogged filters, and check if the issue is house-wide or only on hot water. If pressure is low across the home, inspect and adjust the pressure-reducing valve (PRV) if you’re on city water, or check the pressure tank and switch if you’re on a well. Persistent or uneven low pressure may point to corroded pipes, a failing PRV, or other issues that warrant a plumber.
Target pressure (city water): 50–60 psi (max 80 psi)
Common well settings: 30/50 or 40/60 (cut-in/cut-out)
Pressure tank precharge: 2 psi below cut-in (e.g., 38 psi for 40/60)
What causes low water pressure?
- Partially closed shutoff valves (main or fixture-level)
- Clogged faucet aerators/showerheads or cartridge valves
- Dirty whole-house sediment filters or clogged water softeners
- Issues limited to hot water (partially closed water heater valve, sediment, mixing valve restriction)
- City PRV set too low or failing
- Leaks (hidden slab leaks, irrigation line breaks)
- Old galvanized steel piping with internal corrosion
- Well system problems (low tank charge, misadjusted pressure switch, weak pump)
Tools and materials
- Water pressure gauge with hose-thread connector (and optional lazy hand)
- Adjustable wrench, channel-lock pliers, basin wrench (for faucet work)
- Screwdrivers, hex keys (for cartridges/PRV adjustments)
- Plumber’s tape (PTFE) and pipe dope (where appropriate)
- White vinegar or descaler, small brush, and bucket
- Replacement aerators, showerheads, faucet cartridges, filter cartridges
- Safety gear: gloves, eye protection
Step-by-step troubleshooting
1) Verify the scope and measure
- Test multiple fixtures. If only one fixture is weak, focus there. If whole-house is low, measure at an exterior hose bib with a pressure gauge.
- Check both static pressure (no water running) and dynamic pressure (open an indoor faucet while watching the gauge). A big drop under flow suggests restriction or supply limitations.
- Ask neighbors if they’re seeing low pressure. If yes, call your water utility.
2) Quick checks (15–30 minutes)
- Main and fixture shutoffs: Ensure the main valve and individual angle-stop valves under sinks and behind toilets are fully open. Gate valves can fail; if the wheel spins loosely or won’t open fully, consider replacement with a ball valve.
- Aerators and showerheads: Unscrew, soak in vinegar 30–60 minutes, brush out debris, reinstall. Replace if pitted or damaged ($5–$25 each).
- Faucet/shower cartridges: If one valve is weak, replace its cartridge (typically $15–$60). Follow manufacturer instructions and use a cartridge puller if needed.
3) Filters and softeners (30–60 minutes)
- Whole-house filter: Replace a clogged sediment cartridge ($10–$40). Note the pressure before/after to confirm improvement.
- Water softener: Put in bypass and recheck pressure. If pressure improves, schedule a service, clean the venturi, or address resin bed issues.
4) Hot water only low? (30–90 minutes)
- Verify the cold inlet and hot outlet valves at the water heater are fully open.
- Flush the tank to clear sediment. Connect a hose to the drain, power/gas off, let cool, then flush until clear.
- Mixing/tempering valve: These can clog. Clean or replace if hot-side flow is weak.
5) Check for leaks (30 minutes)
- Meter test: With all water off, watch the water meter. Movement indicates a leak. Isolate by closing the house valve; if meter still moves, the leak is between the meter and house.
- Inspect irrigation zones and crawlspaces for damp soil or hissing.
6) PRV adjustment or replacement (city water) (30–120 minutes)
- Locate the PRV near the main shutoff. Using a gauge, adjust the screw slowly: clockwise raises pressure, counterclockwise lowers. Aim for 50–60 psi.
- If adjustment doesn’t respond or pressure drifts, replace the PRV ($60–$150 part). Add a potable-rated expansion tank on the cold inlet of the water heater if you don’t have one.
7) Well systems (60–120 minutes)
- Pressure switch: Confirm settings (e.g., 40/60). Power off, remove cover, adjust nuts per label. Small turns matter.
- Tank precharge: With system drained and power off, set air charge to 2 psi below cut-in using a tire gauge at the Schrader valve.
- If pressure cycles rapidly or never reaches cut-out, suspect a waterlogged tank or weak pump.
Safety
- Turn off power to electric water heaters before flushing or valve work; set gas heaters to pilot.
- Release pressure and verify water cool enough to handle before opening lines.
- Use two-wrench technique on threaded fittings to prevent twisting pipes.
- Avoid setting pressure above 80 psi; high pressure can cause leaks and water hammer.
Tips for best results
- Keep a pressure gauge installed on a hose bib for ongoing monitoring.
- Flush your water heater annually; replace whole-house filters on schedule.
- If you have a PRV, add a thermal expansion tank and set it to match house pressure.
- Consider high-efficiency showerheads rated for low pressure; look for laminar or pressure-compensating designs.
Common mistakes
- Cranking the PRV too high to mask a restriction, leading to leaks and failed appliances.
- Forgetting to reopen a fixture’s angle stop after repairs.
- Reassembling aerators without the internal flow washer in the correct order.
- Working on a hot water heater without cutting power/gas or allowing cool-down.
When to call a pro
- Static pressure is fine, but dynamic pressure collapses under small demand (possible main line restriction or severe pipe corrosion).
- Galvanized steel supply piping with chronic low flow—repiping with PEX or copper is the long-term fix.
- PRV replacement on tight copper with sweating/brazing required and you’re not comfortable soldering.
- Well pump short-cycling, cavitation noises, or the system fails to reach cut-out.
- Slab leak suspected (warm spots on floor, persistent meter movement).
Costs and time
- Pressure gauge: $10–$20; 5 minutes
- Aerators/showerheads: $5–$40; 15–30 minutes each
- Filter cartridge: $10–$40; 15–30 minutes
- PRV: $60–$150 plus fittings; 1–3 hours DIY or $250–$600 installed
- Expansion tank: $40–$100; 30–60 minutes
- Booster pump (if supply pressure/flow is low): $300–$800 plus install
Address issues from simplest to most complex. Many low-pressure problems are solved with cleaning, filter changes, and valve checks. If measurements point to supply-side limits or aging pipes, planning a targeted repair or upgrade will save time and headaches.