How to Get Rid of Water Hammer Effectively

What is water hammer? Water hammer, also known as noisy pipes, is a common plumbing issue that causes a loud banging or thudding sound when water flow is suddenly stopped or changed. This shockwave travels through your pipes, creating the distinctive noise and potentially damaging your plumbing system over time. Can I fix water hammer myself? Yes, in many cases, you can fix water hammer yourself with a few simple steps and the right tools.

The sound of water hammer can be startling and annoying. It’s that sudden BANG that reverberates through your walls, often after you turn off a faucet, flush a toilet, or when an appliance like a washing machine or dishwasher shuts off its water supply. While it’s a nuisance, it’s also a sign that something isn’t quite right within your plumbing system. If left unaddressed, the repeated shockwaves can lead to leaks, burst pipes, and damage to fixtures and appliances. Fortunately, there are effective water hammer solutions that can bring peace back to your home.

Fathoming the Causes of Water Hammer

To effectively get rid of water hammer, we first need to grasp why it happens. The phenomenon is essentially a pressure surge. When water is flowing rapidly through your pipes and is suddenly stopped, its momentum has nowhere to go. This momentum creates a shockwave that travels back through the pipe. Think of it like a train suddenly braking – everything inside lurches forward.

Several factors can contribute to the occurrence of water hammer:

Fast-Closing Valves: This is the most common culprit. Many modern faucets, solenoid valves in appliances (like washing machines, dishwashers, and ice makers), and even some toilet fill valves are designed to shut off water flow very quickly. This rapid closure doesn’t give the water time to slow down gradually, leading to the shockwave.
High Water Pressure: If your home’s water pressure is set too high, the force of the water itself is greater, making it more susceptible to creating significant shockwaves when flow is interrupted.
Loose Pipes: Pipes that are not securely fastened can vibrate and bang against framing or other objects when a shockwave passes through them, amplifying the noise.
Air in the Lines: While air can sometimes act as a cushion, excessive or trapped air in the plumbing system can also contribute to water hammer, especially if it’s not properly managed.
Long Pipe Runs: Longer stretches of pipe can allow water to build up more momentum, making the shockwave more pronounced when flow is interrupted.

Identifying the Source of the Noise

Before you can fix the problem, you need to pinpoint where the water hammer is occurring. The sound can often guide you, but sometimes it’s more subtle.

Listen Carefully: Try to identify which appliance or fixture, when operated, triggers the banging sound. Is it the kitchen faucet? The washing machine? The toilet?
Test Individual Fixtures: Systematically turn on and off faucets, flush toilets, and run appliances that use water. Pay close attention to when the noise occurs.
Observe Appliance Cycles: For appliances like washing machines or dishwashers, the noise often happens at the end of a fill cycle.

Implementing Effective Water Hammer Solutions

Once you’ve identified the likely cause, you can implement the appropriate water hammer solutions.

1. Installing a Plumbing Shock Arrestor

One of the most effective and widely recommended methods for eliminating water hammer is installing a plumbing shock arrestor. This device is specifically designed to absorb the shockwaves created by sudden changes in water flow.

How a Plumbing Shock Arrestor Works

A water hammer arrestor typically contains a sealed chamber with a piston or diaphragm that separates the water from a pocket of air or gas. When a shockwave occurs, the water pressure forces the piston or diaphragm to move, compressing the air or gas. This compression absorbs the energy of the shockwave, preventing it from traveling through the pipes and creating the banging noise.

Types of Water Hammer Arrestors

Piston Type: These arrestors use a sealed piston that moves within a cylinder. The piston is spring-loaded or has a captive air charge behind it. When a shockwave hits, the water pushes the piston, compressing the air or spring.
Diaphragm Type: These arrestors have a flexible diaphragm that separates the water from a pre-charged air pocket. The diaphragm flexes to absorb the shock.

Where to Install a Plumbing Shock Arrestor

The best location to install an arrestor is as close as possible to the source of the water hammer, typically near the valve of the appliance or fixture that causes the noise. For example, if your washing machine is the culprit, install an arrestor on the hot and cold water supply lines feeding the machine.

Installation Steps (General Guide)

Disclaimer: Always turn off the main water supply to your home before attempting any plumbing work. If you are not comfortable with plumbing, it’s best to hire a professional plumber.

Shut Off Water: Locate the main water shut-off valve for your house and turn it off completely. Open a faucet on the lowest level of your home to drain any remaining water from the pipes.
Locate the Water Source: Identify the specific pipe where the water hammer occurs (e.g., the supply line to your washing machine).
Drain the Line: Open the faucet or valve connected to that line to release any residual water pressure and water.
Install the Arrestor:
- For arrestors that connect directly to a fixture’s supply line (often with a T-fitting), you’ll unscrew the existing supply line, attach the arrestor fitting, and then reattach the supply line.
- Ensure any threaded connections are sealed with plumber’s tape or pipe dope.
Turn Water Back On: Slowly turn the main water supply back on.
Check for Leaks: Carefully inspect all connections for any leaks.
Test: Operate the appliance or fixture that was causing the water hammer to see if the noise has been eliminated.

2. Checking and Adjusting Water Pressure

High water pressure is a significant contributor to water hammer. Ideally, household water pressure should be between 40 and 60 PSI. If your pressure exceeds 80 PSI, it can cause damage and exacerbate water hammer issues.

Measuring Water Pressure

You can measure your home’s water pressure using a simple water pressure gauge that screws onto an outdoor faucet or washing machine hookup.

Installing a Water Pressure Regulator

If your water pressure is too high, the solution is to install a water pressure regulator (also known as a pressure reducing valve or PRV) on your main water line. This device will reduce the incoming pressure to a safe and consistent level for your entire home.

Installation of a Water Pressure Regulator

Location: The PRV is typically installed on the main water line just after the main shut-off valve and before the water branches out to the rest of the house.
Professional Installation Recommended: Installing a PRV involves cutting into the main water line and requires proper soldering or pipe fitting skills. It’s generally recommended to have a plumber install this device to ensure it’s done correctly and to code.

3. Securing Loose Pipes with Proper Pipe Support

Loose pipes are a common, often overlooked, cause of loud water hammer noises. When a shockwave travels through a pipe, if it’s not firmly secured, it can bang against joists, studs, or other pipes, creating a racket that’s mistaken for the water hammer itself.

Why Pipe Support Matters

Proper pipe support prevents pipes from vibrating and moving excessively. When pipes are secured at appropriate intervals, the shockwave is dissipated within the pipe system rather than causing them to physically move and strike surrounding structures.

How to Secure Pipes

Identify Loose Sections: Gently try to move exposed pipes. If they feel loose or wobbly, they need securing.
Use Appropriate Hangers and Clamps: Utilize pipe hangers, straps, or clamps designed for your pipe material (copper, PEX, PVC, etc.). These should be spaced according to plumbing codes and manufacturer recommendations.
Avoid Over-Tightening: Ensure clamps are snug enough to prevent movement but not so tight that they constrict the pipe or damage it.
Add Extra Support: If pipes run long distances without support, add additional hangers.
Resilient Mountings: For particularly problematic areas, consider using resilient clamps or rubber-lined hangers that can further dampen vibrations.

4. Utilizing Air Chambers (Older Method)

Historically, air chambers were the primary method for combating water hammer. These are simple vertical lengths of capped pipe installed above the problematic fixture. The idea is that air trapped in this chamber would be compressed by the shockwave, absorbing the energy.

How Air Chambers Work

When water flow is suddenly stopped, the shockwave travels up into the air chamber. As the water pressure increases, it forces the air in the chamber to compress. This compression absorbs the shock.

Limitations of Air Chambers

While simple, air chambers have a significant drawback: they can become waterlogged over time. The air in the chamber gradually dissolves into the water, and the chamber fills with water, losing its ability to absorb shock. This is why older homes might experience water hammer again if their air chambers are no longer functional.

Recharging an Air Chamber (Temporary Fix)

If you have existing air chambers and suspect they are waterlogged, you can sometimes temporarily recharge them:

Shut off the main water supply.
Open the nearest faucet to drain the system.
If the air chamber has a vent or valve, open it to allow air in. If it’s a simple capped pipe, you might need to unscrew the cap.
Once the system is drained and aired, close the cap or valve and slowly turn the water back on.

However, this is often a temporary fix, and installing a modern water hammer arrestor is a more reliable long-term solution.

5. Considering a Silent Check Valve

A silent check valve can also be a part of the solution, especially when the water hammer is caused by backflow or surges from specific appliances. These valves are designed to open and close smoothly and quietly, preventing the abrupt stoppage of water flow that causes hammer.

When to Use a Silent Check Valve

Silent check valves are particularly useful in situations where a standard check valve might slam shut, causing a noise. They can be installed on individual appliance supply lines or in sections of pipe where backflow is a concern.

6. Installing a Plumbing Expansion Tank

In some cases, particularly in closed plumbing systems where a backflow preventer or check valve is installed, thermal expansion can also lead to pressure increases and contribute to water hammer. A plumbing expansion tank is designed to handle these pressure fluctuations.

How an Expansion Tank Works

Similar to a water hammer arrestor, an expansion tank has a diaphragm separating water from an air charge. When the water heats up and expands, the excess volume enters the tank, compressing the air and preventing a dangerous pressure buildup. While primarily for thermal expansion, the air cushion can also help absorb some shock from water hammer.

When an Expansion Tank is Recommended

An expansion tank is most beneficial in systems with a water heater and a closed system where water cannot easily flow back into the main supply. If your water hammer occurs shortly after the water heater has finished its cycle, an expansion tank might be a good addition.

Addressing Specific Fixtures and Appliances

Washing Machines and Dishwashers: These appliances have solenoid valves that shut off water very quickly. Installing water hammer arrestors on both hot and cold water lines is highly recommended.
Toilets: The fill valve in a toilet can also cause water hammer. Installing a small plumbing shock arrestor on the toilet supply line can resolve this.
Faucets: Single-handle faucets, in particular, can cause water hammer due to their quick shut-off. Again, installing an arrestor near the fixture is the best approach.
Ice Makers and Water Dispensers: These often have small, fast-acting valves that are prone to causing water hammer. A small water hammer arrestor is an effective solution.

When to Call a Professional Plumber

While many water hammer issues can be resolved with DIY methods, there are situations where it’s best to call a professional:

If you are uncomfortable with plumbing work.
If you cannot locate the source of the noise.
If you have high water pressure and need to install a water pressure regulator.
If the problem persists after trying basic solutions.
If you suspect damage to your pipes or system.

A qualified plumber has the tools, expertise, and knowledge of local codes to diagnose and fix even complex plumbing issues, ensuring your system is safe and functioning correctly. They can also properly install devices like PRVs and expansion tanks.

Frequently Asked Questions (FAQ)

Q: Can water hammer damage my pipes?
A: Yes, persistent water hammer can cause significant stress on your plumbing system, leading to leaks, loose fittings, damaged pipe supports, and even burst pipes over time.
Q: How much does it cost to fix water hammer?
A: The cost varies depending on the cause and the solution. DIY installation of a water hammer arrestor might cost $10-$30 per arrestor. Professional installation of arrestors or addressing high water pressure with a water pressure regulator could range from $100 to $500 or more, depending on the complexity.
Q: Will all my noisy pipes stop if I install one water hammer arrestor?
A: Not necessarily. You need to install arrestors near the specific fixtures or appliances causing the hammer. If multiple sources are causing noise, you’ll need multiple arrestors.
Q: Is it safe to ignore water hammer?
A: It is not advisable to ignore water hammer. While it might start as just an annoying noise, it’s a symptom of stress on your plumbing system that can lead to more costly damage if left untreated.
Q: Can a plumber install a silent check valve?
A: Yes, a plumber can install a silent check valve if they determine it is the most appropriate solution for your specific water hammer issue.

By taking a systematic approach to identifying the cause and applying the right water hammer solutions, you can effectively eliminate that disruptive banging from your home and protect your plumbing system for years to come.