Low water pressure in a Keller home can mean two very different things. Sometimes one faucet or shower is weak because a small screen or valve part is clogged. Other times every fixture slows down at once, and the cause sits between the street and your walls. This guide explains how pressure gets lost, what you can safely check, and which patterns need a plumber.
One Fixture or the Whole House?
Start by running each faucet and shower for a moment. If only one fixture is weak, the cause is usually local to it. Faucets have an aerator, a small screen at the tip of the spout that catches sediment and mineral grit. Showerheads have a similar screen or a flow restrictor. Single-handle faucets also use a cartridge, and debris can lodge in its ports after nearby water main work stirs up sediment.
If every fixture is weak, look at the pattern. Low water pressure on both hot and cold at every tap points to the supply side: the main line, the main shutoff or a pressure regulator. If only the hot side is weak everywhere, look first at the water heater or its supply valve.
Why Whole-House Low Water Pressure Happens
Water travels from the street main through the meter and your service line to the house. From there it passes the main shutoff, often a pressure-reducing valve, and the branch lines to each fixture. Pressure is lost anywhere that path narrows, clogs or leaks.
A main shutoff left partly open is a simple, easily missed cause. After a water heater swap, a remodel or any repair that meant shutting off the house, the valve may be turned back only part way. A gate valve with a round handle can look open while its internal gate still blocks part of the pipe. A ball valve is fully open only when its lever lines up with the pipe.
How Regulators, Leaks and Old Pipe Restrict Flow
Many homes have a pressure-reducing valve, or PRV, where the main line enters the house. Inside, a spring-loaded diaphragm and seat throttle incoming water to a steadier household pressure. Over time the diaphragm can stiffen, the strainer can clog, or scale can build on the seat. The valve then passes less water than it should, and pressure sags when several fixtures run.
EPA WaterSense notes in its service water pressure fact sheet that most U.S. plumbing codes require these valves where supply pressure exceeds 80 psi, and it recommends incoming pressure between 45 and 60 psi.
A leak on the buried service line steals water before it ever reaches your fixtures. Older galvanized steel pipe causes a slower decline. As the zinc coating wears away, the steel rusts inside, and rust and scale build up on the pipe walls. The opening narrows year by year, and fixtures farthest from the main line usually feel it first.
Summer Evenings and Neighborhood Demand
July brings peak heat to North Texas, and lawns get watered hard. EPA WaterSense watering tips advise against watering in the middle of the day, when the sun evaporates much of the water, and suggest asking your local water utility when to water. That pushes many sprinkler systems into the same early morning and evening windows. When a whole street draws water at once, pressure in the main can sag.
Your own irrigation system shares the service line with your showers and faucets. If low water pressure shows up only while your sprinklers run, the demand is coming from your own yard. If the dip arrives at the same hour with your system off, neighborhood demand is the likelier cause. Ask a neighbor whether they notice it too, and call the water utility about main repairs or known pressure problems nearby.
A Keller Scenario You Might Recognize
Picture a family whose showers felt fine in the spring. Now, in midsummer, every faucet in the house runs weaker, hot and cold alike. The change comes on slowly, and evenings are worst, when the sprinklers run and someone starts a shower. Cleaning the aerators changes nothing. Out front, a strip of lawn between the meter and the house stays green and soft while the rest of the yard fades.
That pattern points away from the fixtures. Weak flow at every tap, hot and cold, puts the problem on the supply side. A gradual drop, plus a damp strip along the buried line, points toward a service line leak. The evening dip makes the low water pressure more obvious, because irrigation and household use now share a supply that is already losing water. A meter test is the logical next check.
What You Can Safely Check Yourself
These checks need only a flashlight and a few minutes:
- Aerators and showerheads: Unscrew the aerator on a weak faucet and rinse the screen. If flow returns, the problem was local.
- Hot versus cold: Run each side separately at a few fixtures. Weak hot water alone points toward the water heater side.
- Main shutoff: Find the main valve and make sure it is fully open. Turn a gate valve counterclockwise until it stops, without forcing it. Line a ball valve lever up with the pipe.
- Meter leak test: The EPA Fix a Leak Week guidance says to read your water meter before and after a two-hour period when no water is being used. If the reading changes at all, you probably have a leak.
Before the meter test, turn off the irrigation controller and ask everyone to hold off on water use until the second reading.
Safety Notes
- Stuck valves: Do not force an old main shutoff that will not turn. A corroded gate valve stem can snap, leaving you unable to shut the water off.
- Meter boxes: Lift the lid slowly and look before reaching in. Wasps, spiders and other pests sometimes shelter inside.
- Utility equipment: Leave the meter and everything on its street side alone. That equipment belongs to the water utility.
- Pressure regulators: Do not turn the adjusting screw on a PRV without a gauge. Raising it blindly can push pressure high enough to strain fixtures, supply hoses and the water heater.
- Water and electricity: If a leak is wetting outlets, cords or an electrical panel, stay out of the wet area and keep others away.
- Digging: Do not dig to find a suspected service line leak. Other buried utility lines often share the same yard.
When to Call a Professional
Call a plumber if the meter moves with every fixture off, if a wet or sunken spot appears along the service line, or if the whole house loses pressure suddenly. A regulator that no longer holds steady, a main valve that will not open fully, and low water pressure that keeps fading year after year also call for a pro.
Ernie's Plumbing works on main water lines, the buried pipe that carries water from the meter to your home. When a hidden leak is suspected, leak detection can locate it before anyone digs up the yard. If corroded galvanized pipe is choking flow inside the walls, repiping replaces the narrowed lines. You can also read about plumbing service in Keller.
Frequently Asked Questions
Can a pressure-reducing valve cause low water pressure?
Yes. As a PRV ages, its diaphragm, spring or strainer can wear or clog, and the valve lets less water through. The drop shows most when several fixtures run together.
Why is my water pressure only low in the evening?
Summer evenings bring heavy demand, as sprinklers, showers and laundry compete for the same supply across the neighborhood. If the dip happens with your irrigation off, ask neighbors and the water utility about it.
Does low water pressure in the whole house mean I have a leak?
Not necessarily. A partly closed main valve, a failing regulator or narrowed galvanized pipe can cause it too. The meter test helps separate a leak from those causes.
Why is only my hot water pressure low?
When only the hot side is weak everywhere, the cause usually sits at the water heater. A partly closed supply valve, or sediment and scale in the heater's fittings, can restrict hot water flow.
Your Next Step With Ernie's Plumbing
Before you reach out, jot down a few details. Note which fixtures are weak and whether hot, cold or both are affected. Write down when the change started, whether it was sudden or gradual, and when it is worst. Record your meter test result, whether the main valve is fully open, and whether neighbors report the same low water pressure. Mention any wet spots in the yard or along the slab.
With those notes in hand, reach out through our contact page and describe what you found. Ernie's Plumbing can use your notes to plan the visit and start with the most likely cause, whether that is a valve, a regulator or the service line itself.