Proper water pressure is essential for both comfort and the efficient functioning of a home’s plumbing system. Low pressure can make tasks like washing dishes or showering, especially rinsing shampoo, frustrating and ineffective. While people often describe reduced water output as “low pressure,” the real issue is frequently a low flow rate. In this article, we’ll explore common causes of low water pressure or flow and offer practical solutions to help restore your water system to optimal performance.
High Elevation
Homes located at higher elevations are more prone to low water pressure. This is because municipal water systems still rely primarily on gravity to generate pressure. Water is pumped to storage tanks situated at elevated locations, allowing gravity to push water through the system. However, when a home’s elevation approaches the height of these storage tanks, there is less gravitational force acting on the water, resulting in reduced pressure.
This drop in pressure can make it difficult to run multiple fixtures at once and may even lead to low pressure at all fixtures, particularly on upper floors. The most effective solution is to install a pressure booster pump. These pumps either use an expansion tank to maintain stable pressure or feature variable speed motors that adjust water flow based on demand, often eliminating the need for a large expansion tank.
Of all potential water pressure problems, elevation related issues are the only ones directly tied to true pressure loss in the system.
Pipe Corrosion
Most water piping in Massachusetts is made of brass, copper, or various forms of plastic. These materials are all corrosion resistant and typically do not cause low water pressure. However, in some areas, galvanized steel pipe has been used, primarily for water service lines running from the street to the house.
Steel is reactive with water, and once the protective zinc coating wears away, the interior of the pipe begins to corrode. This corrosion builds up inside the pipe, reducing its effective diameter and restricting water flow. Over time, a 1-inch pipe may only allow the same amount of water to pass through as a half-inch or even three eighths inch pipe. This reduced flow rate will first appear as low water flow when multiple fixtures are in use and, if left unaddressed, may eventually affect all fixtures.
Unfortunately, the only permanent solution is to replace the water service line between the street and the house. This typically involves excavating, removing, and replacing the existing line. In some cases, a new line can be pulled through the old pipe with minimal excavation.
Replacing the water service is usually the homeowner’s responsibility and can be costly. If you’re unsure whether your home has a galvanized water service, the best way to check is to inspect the fittings and scratch the pipe. If the fittings are threaded and the scratched pipe appears gray, it is likely galvanized steel.
While copper, brass, and plastic are corrosion resistant, they are not completely immune to flow restrictions. One common issue occurs when brass fittings are used with plastic piping. Because plastic is non reactive, minerals in the water tend to concentrate their effects on the brass, which can eventually lead to internal blockages.
Undersized Piping
If you’re experiencing low water flow in a specific area of your home, the issue may be due to undersized water piping. Pipe sizing is determined based on fixture unit values and the expected water demand for the property. While undersized piping is more common in older homes, it can also occur in newer homes that use PEX piping, which has a smaller inside diameter compared to copper piping, the material for which many sizing standards were originally developed.
Modern standards have increased recommended pipe sizes, while flow rates of fixtures have been reduced to conserve water. Older homes, on the other hand, often feature higher flow rate fixtures combined with smaller diameter piping. This mismatch can result in noticeably low flow when multiple fixtures are in use.
The least invasive solution is to replace older faucets and shower heads with modern low flow fixtures, which can help balance the demand across the system. However, the most effective long term fix is to replace the undersized piping. This can be a significant project and may require remodeling, depending on the age of the piping and the layout of the home.
Appliance Operation
The operation of certain appliances can affect the water system’s flow rate or pressure. One of the most obvious examples is the pressure booster pump. If it begins to malfunction or stops operating properly, water pressure may fluctuate, usually decreasing, but occasionally increasing if controls fail.
Tankless water heaters can also impact water flow. If the unit cannot adjust the temperature quickly enough, it may restrict the flow to allow more time for heating. This issue may be caused by an undersized water heater, but more commonly results from a buildup of mineral deposits or corrosion within the heat exchanger.
These deposits insulate the internal piping, reducing heat transfer efficiency and increasing the time required to heat water. The solution is to flush the heat exchanger with a descaling solution or a concentration of vinegar to remove mineral buildup and restore proper performance.
Partially Closed Or Broken Valves
Valves are used throughout a plumbing system to control water flow and isolate sections of piping. As these valves age, their internal components can weaken, leading to incomplete opening or closing during use. This issue is most common in older gate valves, but it can also occur in modern quarter turn ball valves.
Valves typically do not fail spontaneously. Problems usually arise when the valve is operated, especially if excessive force is applied while opening or closing. This can result in a partially or fully obstructed pipe, which reduces water flow. Such issues are often identified quickly, since the system is usually tested after a shutoff, making any drop in flow rate immediately noticeable.
In many cases, a broken valve can be diagnosed by feel, prompting further inspection of downstream fixtures. The only permanent fix for a damaged valve is to remove and replace it.
Another common cause of low flow is a valve that has been left partially closed by mistake. This typically occurs during repairs or new installations, when a technician opens the valve just enough to allow water through while checking for leaks. If the valve is not fully opened afterward, the reduced opening can restrict water flow. Fortunately, this is an easy fix. Simply fully open the valve to restore normal flow.
Clogged Screens, Flow Restrictors, Or Check Vavles
If only one fixture in your home is experiencing low water flow, the issue is likely due to debris buildup in a component of that specific fixture. Most modern faucets and shower heads include screens, flow restrictors, and check valves. These components are designed to conserve water, prevent cross contamination, and stop large debris from entering the fixture. However, because they have small openings, they can easily become clogged with fine particles, leading to a noticeable drop in flow over time.
Shower heads are typically easy to clean. Simply remove the shower head from the arm and clear any debris from the screen or flow restrictor. Faucets, on the other hand, have several areas where debris can accumulate. The most common is the aerator at the outlet of the faucet, which contains a series of screens that trap particles. There may also be screens at the valve connections. Check valves can be found at the valve connections or inside the hoses of pull down faucets.
In some cases, debris can become lodged inside the faucet cartridge, causing reduced flow. Restoring full performance may require disassembling the faucet to clean or replace affected parts.
Final Thoughts
Low water pressure and reduced flow can be frustrating, but identifying the root cause is the first step toward restoring comfort and functionality to your plumbing system. Whether the issue stems from aging pipes, faulty valves, mineral buildup, or elevation challenges, addressing it early can save you time, money, and inconvenience down the road. If you’re experiencing persistent water flow issues or need expert guidance, don’t hesitate to contact our team. We’re here to help diagnose the problem and recommend the most effective solution for your home. Contact us today either by phone or through the form on our website to get started.