Buying a house with low water pressure

Low water pressure on a home inspection

If you're buying a house with low water pressure on the inspection report, the cause can be a clogged faucet screen or corroded pipe, and the report alone can't tell you which. Before your deadline, get a licensed plumber to put a gauge on the house and name the cause. That reading decides whether you ask the seller for a few hundred dollars or several thousand.

Key takeaways

• When street pressure tops 80 psi, the International Residential Code calls for a pressure-reducing valve where the water service enters the house.
• Weak flow at every tap, not just one, can point to corroded pipe or a failing pressure regulator.
• A regulator swap takes a plumber one to two hours when the valve is easy to reach, at $75 to $200 an hour.

How much does it cost to fix low water pressure?

It depends on the cause, and the ranges below differ mostly by scope.

Here's how that plays out. Say the gauge reads low and the plumber traces it to a failed regulator on a standard ¾-inch line. The table's replacement rows for a standard regulator run from $200 to $656, so your request lands in the hundreds, not the thousands. If the plumber finds corroded pipe instead, you're in the bottom two rows, and a repipe's cost turns on the house's size and materials.

Kept prices every line of an inspection report for $79, usually under 4 hours, and marks the ones that need a professional quote, like a whole-house repipe.

What does low water pressure on the report mean?

It means the inspector saw weak flow, not that they measured anything. Under the International Association of Certified Home Inspectors (InterNACHI) standards, the inspector runs the faucets and reports a problem by watching the flow at two fixtures running at once. The same standards say the inspector doesn't have to measure pressure or flow rate.

They also don't have to find the cause, or inspect pressure pumps and bladder tanks. So the line on your report is an observation. A plumber with a pressure gauge turns it into a psi number, a cause, and a scope of work. On a private well, ask the plumber to look at the pump and tank on the same visit. If the well water was tested too, well water test failed covers what a bad result means.

Is low water pressure bad?

It's a comfort problem first. InterNACHI puts the low line at 40 psi: below it, showers go weak and washing machines and dishwashers stop working properly.

What matters for your money is the cause. InterNACHI calls clogged aerators and showerheads easy fixes. Weak flow throughout the house is different: it can signal corroded pipes, mineral buildup, or a failing pressure regulator. San Diego's water department adds that a regulator can fail closed and that leaks can also drop pressure.

Can it be fixed? Yes, even when the street supply is the weak link. Where the supply can't serve the fixtures, the code's minimum-pressure section calls for raising it with an elevated water tank, a pressure booster system, or a booster pump.

If your report also notes an active leak, send that to a licensed plumber before your deadline, on the same visit. If it flags polybutylene supply pipe, have the plumber look at that too; see polybutylene pipes on an inspection report.

Is high water pressure dangerous?

It can damage fixtures, appliances, and plumbing. Section P2903.3.2 of the International Residential Code caps static pressure in the house at 80 psi. Where the main pressure is higher, the code calls for "an approved pressure-reducing valve" at the connection to the water service pipe. So 60 psi is inside the limit, and 120 psi is well over it.

Above that line, InterNACHI says pressure "can damage fixtures, appliances, and plumbing connections, leading to leaks and premature failure of expensive equipment." It also wastes water and raises utility bills. San Diego's water department says the most common cause of a sudden rise in pressure is a faulty regulator on the property.

If the plumber's gauge reads over the limit, ask whether a regulator is there and working. Your local building department or a licensed plumber answers what code applies at your address.

What should you ask the seller for?

Ask for the fix the plumber named, at the plumber's price. A request line names the scope, the trade, and the figure: "Replace the failed pressure-reducing valve at the water service, licensed plumber, per attached written bid."

A range from the table can hold your place while you wait for the plumber. The bid is what you attach. For how to get that visit booked inside your window, see how to get repair estimates during the inspection period.

What to ask for after a home inspection covers where this line sits next to the rest of your list. The buyer repair request letter template has the wording around it. Your contract sets the deadline and your options, so confirm both with your agent.

What if the seller says no?

You have three moves. Ask for a credit instead of the repair. Ask for a smaller amount that covers the regulator or the worst section of pipe. Or decide whether the finding is worth leaving over.

Treat a regulator in the hundreds as a line to negotiate. Corroded pipe with a repipe bid is a bigger question. When to walk away after a home inspection walks through that call. The plumbing items elsewhere on your report matter here too; see plumbing findings on an inspection report.

Who is responsible for low water pressure in a house?

Ask your local water utility where its side ends. In San Diego, for example, the property owner is responsible for the water system from the meter on, and regulators are the owner's too. Ask too whether the utility will test pressure at the street. San Diego tests at the nearest fire hydrant, and if the reading is normal, it points to the plumbing on the property.

How much does a plumber charge to fix water pressure?

HomeAdvisor says labor is the biggest part of a regulator job. Plumbers charge $75 to $200 an hour, and a straightforward replacement takes one to two hours if the regulator is easy to reach. For pipe work, go by the table above until the plumber's bid arrives.

If low water pressure is one line on a long report, upload the whole report to Kept and spend your remaining days on the lines that need a plumber's bid.

Sources

• InterNACHI, Standards of Practice for Performing a General Home Inspection
• InterNACHI, Water Under Pressure: Why Temperature, Pressure, and Flow Matter
• International Residential Code, Section P2903.3, via UpCodes
• City of San Diego Public Utilities, Your Meter, Water Pressure and Plumbing System
• HomeAdvisor, How Much Does a Water Pressure Regulator Replacement Cost?
• Homewyse, Cost to Install Pressure Regulator Valve
• Doug Herrell Plumbing, Plumber for Low Water Pressure