Why is my water pressure low in an older home?

Is it low pressure or low flow?

People say low pressure, but most of the time they mean low flow: water comes out of the tap slower than it should. The difference matters because the fixes are different.

Pressure is the push behind the water when nothing is running. You can measure it with a simple gauge that screws onto an outdoor spigot or the washing machine bib. Flow is how much water actually reaches the fixture once it's open. A house can have decent pressure at the gauge and still have weak flow at the shower because the pipe between the two is choked with rust.

Try this first. If every fixture in the house is weak, hot and cold, the problem is upstream: the service line, the main shutoff, the meter valve, or a pressure-reducing valve. If it's one or two fixtures, the problem is local. If it's only hot water, look at the water heater and the hot piping.

Which older-home problems cause low pressure?

Older homes across our service area share a short list of usual suspects, and many houses have more than one at the same time, which is why the problem creeps up over years.

• Galvanized steel supply pipe. Common in homes built before the 1960s and still in many Main Line and rowhome basements. It rusts from the inside, and the buildup narrows the pipe a little more every year.
• A worn pressure-reducing valve (PRV). If your home has one, it's a bell-shaped fitting near the main shutoff. When the spring or diaphragm inside fails, pressure drops, spikes, or wanders.
• A partially closed valve. The main shutoff, the meter valve, or the curb stop out at the sidewalk may have been left half-open after past work. Old gate valves also fail with the gate partly dropped.
• Clogged aerators and cartridges. Rust flakes and scale from old pipe collect in the screen at the faucet tip and inside shower valve cartridges.
• An undersized or corroded water service. The line from the street to the house may be old lead, galvanized, or simply too small for the fixtures added over the years.

How do I narrow it down at home?

You can rule out a lot before calling anyone. Start at the faucet. Unscrew the aerator and run the tap without it. If flow jumps, clean or replace the aerator. Next, check the shutoff valves under sinks and behind toilets, and make sure they are fully open.

Then go to the basement. Find the main shutoff and confirm it is open all the way. If it's a round-handle gate valve, turn it counterclockwise until it stops. Look for a PRV and note whether it's sweating, corroded, or humming.

Screw a pressure gauge onto an outdoor spigot with everything off and note the reading. Your water supplier can tell you what's normal for your street. If the gauge reads low with no water running, the problem is at the service, the meter, the curb stop, or the PRV, not inside the house.

When is the water service line the problem?

The water service is the pipe that runs from the water main under the street, through the curb stop, and into your basement. In older Philadelphia, Ardmore, and Bensalem homes it may be original: lead, galvanized steel, or a small copper line put in for a house that had one bathroom. Add a second bath, a dishwasher, and a lawn spigot, and the old line can't keep up.

Signs that point to the service line: pressure is low at every fixture, the gauge reads low at the spigot, the main shutoff and meter valve are fully open, and there's no PRV or the PRV checks out. Rusty water first thing in the morning is another clue with a galvanized service.

This is work our underground crews do in-house, from the excavation to the tie-in at the meter, with permits pulled and inspections scheduled. Philadelphia L&I and your township have their own rules for service replacement, so confirm current requirements. In Philadelphia, PWD generally maintains the portion from the main to the curb stop and the owner is responsible from the curb stop in; the PWD lead service line program may apply to lead lines, so check current PWD programs.

What affects the estimate, and what should I do next?

There's no single fix for low pressure, so there's no single answer on cost, and we don't quote until we've looked. What drives the estimate is the cause.

A clogged aerator or a stuck valve is a quick repair. A new PRV is a straightforward fitting swap near the main shutoff. Replacing a bad section of galvanized pipe depends on where it runs and how easy the wall or ceiling is to open. A water service replacement depends on the length from the curb to the house, the depth, what's on the surface (sidewalk, driveway, planting beds), and permit and inspection requirements from Philadelphia L&I or your township.

We start with a pressure reading, a look at the piping, and a straight conversation about what's causing it. Then we give you options, from the small fix to the long-term one. No high-pressure sales. We give you options. If you've already been quoted a service replacement or a major pipe job, ask us for a free second opinion on qualifying larger projects.