Understanding your home's water pressure: what's normal in NoVA

Normal home water pressure is 40 to 80 PSI (pounds per square inch). Below that range, showers trickle and appliances fill slowly. Above it, your pipes, fixtures, and appliances take a beating, and high pressure is often the bigger problem of the two.

What 40 to 80 PSI gets you

Inside that range, you get strong, steady flow without stressing your plumbing.

Below 40 PSI, everyday things get frustrating. The shower feels like a trickle, the washing machine and dishwasher take longer to fill, and garden sprinklers barely reach past the sidewalk.

Above 80 PSI, the damage is quieter. High pressure shortens the life of your water heater, keeps faucets dripping, wears out faucet cartridges, and makes appliance connections leak more often. We've seen pressure over 100 PSI blow out faucet cartridges and washing machine hoses without warning.

Why NoVA homes run high or low

Pressure in the public mains varies widely with elevation and distance from pumping stations and storage tanks. Two houses a few miles apart can see very different numbers.

On higher ground, in parts of McLean or Vienna for example, pressure can run low because the water has farther to climb. In low-lying areas and near pumping stations, it can run high, and we regularly find homes there well above 80 PSI.

Older pipes add a third factor, which we'll get to below.

How our technicians measure it

The number that matters is static pressure, read at a hose bib with no water running anywhere in the house. Our technicians take readings at different times of day, because pressure can shift with neighborhood demand, and one morning reading doesn't tell the whole story.

From there, the readings point us toward a high-pressure fix, a low-pressure hunt, or occasionally both.

When pressure is too high: a PRV

If your pressure sits above 80 PSI, the fix is a pressure reducing valve, or PRV. It installs on your main water line and regulates pressure for the whole house.

It's not a DIY job. The valve has to be sized for your home's water demand and installed with proper shutoffs. What the installation involves depends on your setup and local codes, and we give a written, upfront quote before any work begins. Once it's in, your water heater, appliance connections, and faucet cartridges stop taking the extra wear.

When pressure is too low: what we check

Low pressure has several possible causes, from a simple fix to pipe replacement. Our technicians work through them in order:

• The main valve. It should be fully open. We've found partially closed valves in homes where a previous owner tried to fix high pressure the wrong way.
• Hidden leaks. A significant leak can drop pressure throughout the house. We check the meter with everything off and use water leak detection to find the source.
• Pipe material. Older homes that still have their original galvanized steel pipes are the usual suspects.
• Time of day. If pressure drops sharply every evening, the problem may be on the utility's side. In that case, contact Fairfax Water or your local utility to report it.

Old pipes and hard water

Galvanized steel pipe corrodes from the inside. Over decades, rust and scale narrow the inside of the pipe dramatically, and flow drops with it. Northern Virginia's moderately hard water adds mineral buildup on top of that. If you have galvanized pipes and low pressure, replacement is usually the only permanent fix, and PEX repiping is one of the ways we do it.

Copper handles our water better than galvanized steel, though even copper can pick up some scale over decades. PEX, common in newer homes, resists mineral buildup.

If you have good pressure at some fixtures and poor pressure at others, especially if it's getting worse over time, a restriction in that branch of the plumbing is the likely culprit.

Get it diagnosed, not guessed

Pressure problems are often a symptom of something else. What looks like a simple PRV job can turn up corroded pipes or a line that was sized wrong, and both PRV work on the main line and repiping need the right materials, permits, and code compliance. That's what our diagnostic services are for.

Pioneer Plumbers is a family-owned, licensed and insured company. We'll measure your pressure, find the cause, and give you a written, upfront quote before any work begins. Call us at (703) 508-3088.