Updated 2026-06-02 · Reviewed by Jose A. Vital, Owner & Master Plumber
First: Is the Low Pressure at One Fixture or the Whole House?
This is the single most useful question to answer before anything else. Check multiple fixtures — kitchen faucet, bathroom sink, shower, and a hose bib outside if possible.
- Low at one fixture only: The problem is local — typically a clogged aerator, a partially closed shut-off under the sink, or a failing cartridge in that faucet.
- Low at all hot water fixtures but not cold: Your water heater is the likely culprit — sediment buildup or a failing dip tube.
- Low everywhere, all at once: The cause is upstream — the pressure reducing valve, the main shut-off, the meter, the service line, or a hidden leak.
Common Causes of Low Water Pressure — and How to Check Each
1. Clogged Aerator or Showerhead
Mineral deposits from hard water (common throughout Pflugerville and Round Rock) build up inside aerators and showerhead nozzles over time. Water has to push through a smaller and smaller opening, and pressure drops at that fixture.
Check it yourself: Unscrew the aerator from the faucet tip (it may unscrew by hand or need pliers wrapped in a cloth). If you see a crusty white or brown buildup on the screen, soak it in white vinegar for an hour and rinse. For a showerhead, fill a bag with vinegar and rubber-band it over the head overnight.
2. Partially Closed Shut-Off Valve
The main shut-off and the per-fixture valves under sinks can get bumped or partially closed during other work. A valve that is even 20% closed can cut flow noticeably.
Check it yourself: Look under sinks and at the main shut-off near your meter or where the main enters the house. Make sure all valves are fully open (counterclockwise on a gate valve; lever parallel to the pipe on a ball valve).
3. Failing Pressure Reducing Valve (PRV)
Most Central Texas homes on municipal water have a PRV — a bell-shaped valve on the main line, usually near the front of the house or in a utility room. It keeps city supply pressure (often 80–120 psi) down to a safe 50–65 psi. PRVs typically last 10 to 15 years.
Signs it is failing: Pressure dropped across the whole house recently with no other explanation, or your pressure fluctuates unpredictably throughout the day.
What to do: A plumber can test inlet and outlet pressure across the valve in a few minutes. If it is the PRV, replacement typically takes less than an hour.
4. Sediment Buildup in Pipes
Older galvanized steel pipes corrode from the inside and gradually restrict flow. Central Texas homes built before the mid-1980s sometimes still have galvanized supply lines. The restriction usually gets worse over years rather than appearing suddenly.
Signs: Gradual pressure decline over the past few years, rust-colored water occasionally, and pipes that look orange-brown when cut open. The long-term fix is repiping with copper or PEX.
5. Water Heater Sediment
If only your hot-water fixtures have low pressure, look at the water heater. Sediment accumulates at the bottom of the tank over time and can partially block the dip tube or inlet connection.
What to do: Flushing the tank annually removes loose sediment. If the tank is old and sediment is severe, a replacement may be more cost-effective than flushing.
6. Hidden Leak
A leak in a supply line — especially a slab leak running under your foundation — can bleed off enough pressure to affect flow throughout the house. These are often accompanied by unexplained high water bills, the sound of running water when everything is off, or hot spots on the floor.
Quick check: Turn off every water-using appliance and fixture, then watch your water meter for 30 minutes. If it moves, you have a leak somewhere.
When to Call a Licensed Plumber
- Your pressure is low throughout the whole house and you cannot find an obvious cause.
- You suspect a failing PRV.
- Your water meter shows movement with everything off (hidden leak).
- Your pipes are old galvanized steel and pressure has declined over years.
- You have low pressure along with discolored or rusty water.
Alberto Plumbing diagnoses low-pressure issues throughout Pflugerville, Round Rock, Hutto, and Austin. Call (512) 429-6933 for a free phone consultation with Jose A. Vital, TX Master Plumber M-39647. Same-day service is often available.
Frequently asked questions
A sudden drop usually points to a burst pipe, a main supply disruption from your utility, or a shut-off valve that was accidentally partially closed. Check your other fixtures first — if all of them are low, call your utility before calling a plumber.
Residential water pressure should be between 40 and 80 psi. Most plumbers aim for 55 to 65 psi as a comfortable range. Below 40 psi and you will notice weak showers and slow-filling appliances.
No. A clogged aerator only affects that one fixture. If low pressure is limited to one faucet, start by unscrewing the aerator (the screen at the tip of the spout) and cleaning it. If pressure is low at every fixture, the cause is further upstream.
A pressure reducing valve (PRV) sits on your main water line near where it enters the house and throttles the municipal supply pressure down to a safe residential level. A failing PRV can cause pressure to drop house-wide — or, if it sticks open, cause pressure to spike dangerously. Signs of a failing PRV include sudden whole-house low pressure, pressure that varies wildly, or a water hammer banging sound.
Yes — especially a slab leak or a hidden leak inside a wall. If you have low pressure with no obvious reason, watch your water meter for a few hours with everything turned off. If the meter is moving, you likely have a leak somewhere in your system.
It depends on the cause. A clogged aerator is free to fix yourself. Replacing a PRV typically runs $250 to $500 installed. If the cause is a corroded galvanized pipe section or a slab leak, costs can be higher. Alberto Plumbing offers free diagnostic quotes — call (512) 429-6933.