Low Water Pressure in Your House? Causes and How to Fix It

Low water pressure is one of the most frustrating plumbing problems a homeowner can face. Showers feel weak, faucets take forever to fill a pot, and washing machines run longer cycles. In New York City, where building plumbing ranges from brand new to over a century old, low water pressure is an especially common complaint.

The good news is that low water pressure usually has a diagnosable cause. In this guide, we will walk through the most common reasons for low water pressure, some troubleshooting steps you can try yourself, and when it is time to call a Licensed Master Plumber.

Common Causes of Low Water Pressure

Corroded or Clogged Pipes

This is by far the most common cause of low water pressure in NYC homes and buildings. Many older buildings, particularly those built before the 1960s, have galvanized steel water supply pipes. Over decades, the interior of these pipes corrodes and narrows as mineral deposits, rust, and scale build up inside. A pipe that started with a 3/4-inch opening may now have an effective opening of 1/4 inch or less. The result is a dramatic reduction in water flow throughout the building.

Galvanized pipe corrosion is especially prevalent in neighborhoods with older housing stock, including much of Brooklyn, Queens, the Bronx, and Manhattan below 96th Street. The only permanent fix is to replace the galvanized pipes with copper or PEX, which requires a Licensed Master Plumber and typically a DOB permit.

Water Leaks

A hidden leak diverts water away from your fixtures, reducing the pressure at your faucets and showerheads. Leaks can occur inside walls, under floors, in the foundation, or in the water service line between the street and your building. Signs of a hidden leak include unexplained increases in your water bill, damp spots on walls or ceilings, the sound of running water when no fixtures are in use, and low pressure that developed suddenly rather than gradually.

Professional water leak detection can locate hidden leaks without tearing apart walls.

Faulty Pressure Reducing Valve (PRV)

Many NYC buildings have a pressure reducing valve installed where the water service enters the building. This valve reduces the high pressure from the city main (which can be 80 to 150 psi) to a safe level for your plumbing (typically 40 to 60 psi). If the PRV fails or is set too low, it can restrict water flow and cause low pressure throughout the building. PRVs typically last 10 to 15 years and should be replaced if they are not maintaining proper pressure.

Municipal Supply Issues

Sometimes low water pressure is not your building's fault at all. The NYC DEP may be performing maintenance on a water main in your area, a water main break may be affecting supply, or demand during peak usage times can temporarily reduce pressure in your neighborhood. If your neighbors are experiencing the same problem, the issue is likely on the city's side.

You can check the NYC DEP's website or call 311 to report or inquire about water pressure issues in your area.

Mineral Buildup in Fixtures

Sometimes the pipes are fine, but the fixtures themselves are clogged. Mineral deposits accumulate in faucet aerators, showerheads, and supply valves over time, restricting flow. This is an easy fix: unscrew the aerator or showerhead, soak it in white vinegar for a few hours to dissolve the mineral buildup, and reinstall it.

Partially Closed Valves

It sounds simple, but a partially closed shutoff valve is a surprisingly common cause of low water pressure. The main shutoff valve, the water meter valve, or individual fixture shutoff valves may not be fully open. This can happen after plumbing work when a valve is not reopened completely, or when someone accidentally bumps a valve handle.

DIY Troubleshooting Steps

Before calling a plumber, try these troubleshooting steps:

1. Check all fixtures. Is the low pressure affecting just one fixture, one room, or the entire building? If it is only one fixture, the problem is likely localized (a clogged aerator or partially closed valve). If it affects the entire building, the cause is systemic.
2. Check hot and cold separately. If only the hot water pressure is low, the problem may be with the water heater, a stuck valve on the hot water outlet, or sediment in the hot water piping.
3. Clean aerators and showerheads. Remove and clean the aerators on your faucets and soak your showerhead in vinegar. Reinstall and test.
4. Check shutoff valves. Locate the main shutoff valve and any individual fixture shutoff valves. Make sure they are fully open (turned counterclockwise as far as they will go).
5. Ask your neighbors. If neighbors are also experiencing low pressure, the issue is likely with the municipal water supply or a shared building system.
6. Check the PRV. If you have a pressure reducing valve, note the current reading on the pressure gauge (if equipped). Normal residential water pressure is 40 to 60 psi. Below 40 psi feels noticeably low.

NYC-Specific Causes of Low Water Pressure

Old Galvanized Pipes

As mentioned above, galvanized steel pipes are the primary culprit in most NYC low-pressure complaints. The city's enormous stock of pre-war housing means millions of buildings still have original galvanized supply piping. Complete pipe replacement is the only permanent solution, but it is an investment that significantly improves water pressure, flow, and water quality.

High-Rise Buildings

In tall buildings, water pressure decreases on upper floors because gravity works against the water supply. Buildings typically use booster pumps and rooftop water tanks to maintain adequate pressure on upper floors. If your building's booster pump is malfunctioning or the rooftop tank has issues, upper-floor residents will notice low pressure first.

Shared Water Service Lines

Some older NYC buildings share a water service line from the street. During peak usage (mornings and evenings), the shared line may not provide enough flow for all buildings simultaneously, resulting in intermittent low pressure.

When Low Pressure Signals a Bigger Problem

Low water pressure should not be ignored. In some cases, it can indicate:

• A hidden leak that is wasting water and potentially causing structural damage.
• Pipe corrosion that will eventually lead to pipe failure and water damage.
• A failing PRV that could allow dangerously high pressure to reach your fixtures if it fails in the open position.
• Deteriorating infrastructure that will only get worse and more expensive to address over time.

When to Call a Licensed Master Plumber

Contact a professional when:

• Low pressure affects the entire building and basic troubleshooting has not helped.
• The pressure has been declining gradually over months or years (a strong indicator of corroding pipes).
• You suspect a hidden water leak.
• The pressure reducing valve needs replacement or adjustment.
• Your building has galvanized steel pipes that need to be replaced.
• You are in a high-rise and suspect a booster pump problem.
• You want a professional water pressure test to diagnose the issue.

Karl's Plumbing, Heating & Cooling has been solving residential plumbing problems across New York City for four generations. Our Licensed Master Plumbers (LMP #921 and LMP #2060) can diagnose the cause of your low water pressure, recommend the right solution, and handle everything from pipe replacement to leak detection.

Call us at (800) 721-3200 or (718) 263-8600. We service all five boroughs, Long Island, and Westchester.