How do I test my home's water pressure without special equipment?

Thread a standard hose-bib pressure gauge onto an outdoor spigot — they are sold at most hardware stores for around ten dollars. Turn the spigot on fully and read the dial. Normal residential pressure falls between 45 and 80 psi; anything consistently below 40 psi points to a supply problem, a failing PRV, or significant pipe restriction. Test it in the morning before heavy household use for the most accurate baseline reading.

Can a water softener or filter cause low pressure?

Yes. Whole-house filters have a sediment cartridge that needs to be replaced on a regular schedule — a clogged cartridge can noticeably reduce flow to the entire house. Water softeners can also cause pressure drops if the resin bed is fouled or if the bypass valve is not fully open. Check both if they are installed upstream of your fixtures and you have ruled out other causes.

Why is my hot water pressure lower than my cold water pressure?

When hot-side pressure is noticeably weaker than cold, the restriction is usually between the water heater and the fixtures rather than on the main supply line. Common causes include a partially closed shutoff valve on the water heater's outlet, sediment buildup inside the heater's tank or connecting pipes, or — in older homes — corroded galvanized hot-water lines that have scaled up more than the cold-side pipes. Flushing the water heater annually helps slow sediment accumulation.

Will low water pressure get worse on its own, or can it stabilize?

It depends on the cause. A clogged aerator stays about the same until you clean it. A failing PRV can deteriorate further and eventually restrict flow significantly or fail open and cause overpressure. Corroded galvanized pipes continue to scale inward over time, so pressure typically worsens slowly year over year. A hidden leak tends to grow, not shrink. In short: most causes of low pressure trend in the wrong direction without intervention, which is why it is worth diagnosing sooner rather than later.

Low Water Pressure in Your House? Here Are the Usual Suspects

Low water pressure in your house usually traces back to one of a handful of causes: a partially closed shutoff valve, a failing pressure regulator, mineral buildup inside aging pipes, or an active leak somewhere in the system. Most of these you can diagnose yourself in under 20 minutes. A few of them — particularly hidden leaks and corroded galvanized pipes — need a plumber before they turn into something much more expensive. Here is how to work through the list systematically.

Start With the Obvious Checks

Before you call anyone, walk through these in order.

Check whether it is one fixture or the whole house. Turn on faucets in the kitchen, a bathroom, and an outdoor hose bib. If pressure is weak everywhere, the problem is upstream — at the meter, the main shutoff, or the pressure regulator. If it is only one faucet, the aerator screen is probably clogged with sediment.
Unscrew the aerator. That small mesh screen at the tip of the faucet collects calcium and debris over time, especially in areas with hard water. Soak it in white vinegar for 30 minutes, rinse it, and reinstall. If pressure returns, you are done.
Check the main shutoff valve. It is usually near the water meter at the street, or where the supply line enters the house — often in a garage, utility closet, or crawl space. A ball valve should be fully parallel to the pipe; a gate valve (the round-handle type) should be turned all the way counterclockwise. A valve that is only three-quarters open can cut pressure noticeably.
Ask your neighbors. If two or three houses on your street are experiencing the same thing on the same morning, the issue is with the municipal supply — a main break, a pressure zone adjustment, or scheduled maintenance. In that case, the fix is on the utility’s side and you just wait.

The Pressure Regulator: The Most Overlooked Culprit

Most homes built in the last several decades have a pressure-reducing valve (PRV) on the main supply line, typically near where the water enters the house. Its job is to step down the street pressure — which can run anywhere from 60 to well over 100 psi — to a safe working range for your plumbing, usually 50–60 psi.

PRVs are mechanical devices with a rubber diaphragm inside, and they wear out. When they fail, they can stick in a partially closed position and starve the whole house of pressure. They can also fail in the opposite direction and let pressure run dangerously high, which is a different problem.

You can test your static pressure with an inexpensive gauge that threads onto a hose bib — they cost about ten dollars at a hardware store. If the reading is below 40 psi and the municipal supply is fine, a failing PRV is a strong suspect. Replacing one is a straightforward job for a plumber but involves cutting into the supply line, so it is not a weekend DIY project for most homeowners.

Mineral Buildup and Galvanized Pipes

If your home was built before the mid-1980s and still has its original plumbing, there is a good chance the supply pipes are galvanized steel. Galvanized pipe corrodes from the inside out. Over decades, rust and mineral scale accumulate until the interior diameter is a fraction of what it once was — imagine trying to drink through a straw that is slowly filling with sand.

The telltale signs:

Pressure has been declining gradually over years, not suddenly
The water has a faint rust or metallic taste
You see reddish-brown staining in toilet tanks or around faucet bases
Pressure is noticeably worse at fixtures farthest from the water heater or main

There is no cleaning solution that reverses this. Once galvanized pipe has corroded to this degree, the long-term fix is repiping — replacing the old supply lines with copper or cross-linked polyethylene (PEX). It is a significant project, but it is also a one-time fix that typically restores full pressure and eliminates the rust problem entirely. If you are in this situation, it is worth getting an assessment from a licensed plumber who can scope the pipes and give you an honest picture of how far the corrosion has progressed.

When Low Pressure Is Actually a Leak

This is the scenario that warrants the most urgency. A slow leak — especially one inside a wall, under a slab, or beneath a concrete floor — can bleed enough pressure from the system to be noticeable at the faucets. Unlike a burst pipe, these leaks do not announce themselves with water pouring across the floor. They hide.

Signs that a hidden leak might be behind your pressure drop:

Your water meter is spinning when every fixture in the house is off (turn off all faucets and appliances, then check the meter’s low-flow indicator — usually a small triangle or dial)
You hear water running faintly inside a wall when nothing is on
A section of floor feels warm underfoot for no obvious reason (a common sign of a slab leak on a hot-water line)
Your water bill has climbed without any change in usage
You notice soft spots, discoloration, or bubbling in drywall or flooring

If two or more of these are present alongside low pressure, stop guessing and call for professional leak detection. Modern detection uses acoustic listening equipment and thermal imaging to locate a leak without tearing open walls — which means far less repair work once the source is found. The longer a slab or wall leak runs, the more structural damage accumulates, so this is not a situation where waiting a few weeks makes sense.

What Not to Do

Do not crank up the pressure at the PRV yourself if you are not sure what the current reading is. Overpressure stresses every joint, valve, and appliance in the house and can shorten the life of your water heater significantly.
Do not assume the problem is the municipality’s without actually checking your own shutoffs and pressure first. Utility issues are relatively rare; internal issues are common.
Do not ignore gradual pressure loss. A slow decline over months is the classic pattern of either progressing pipe corrosion or a slow leak — both of which get worse and more expensive the longer they go unaddressed.

When to Call a Plumber

Handle it yourself if the problem is a clogged aerator, a partially closed valve, or a confirmed utility outage.

Call a plumber if:

Pressure is low house-wide and the shutoffs are fully open
Your PRV test reads below 40 psi and the street supply is normal
You have galvanized pipes and pressure has been declining for years
Any of the hidden-leak indicators above are present
You have already replaced the aerators and checked the valves and nothing has changed

Low water pressure is almost always fixable. The question is whether the fix is a five-dollar aerator or a repiping project — and the only way to know is to work through the list above honestly.

If you are in the Corona area and the DIY checks have not turned anything up, the team at RT Olson Plumbing, Heating and Air Conditioning can diagnose the problem properly — whether that means a pressure test, a leak detection scan, or an evaluation of your existing pipes. Reach them at (951) 344-5596.