What is water hammer? Water hammer, also known as pipe banging noise or hydraulic shock, is a pressure surge in a plumbing system that occurs when water flow is suddenly stopped or changes direction. Can I stop water hammer myself? Yes, you can often stop water hammer yourself with some basic tools and understanding of your plumbing. Who is affected by water hammer? Anyone with a plumbing system, especially those with older pipes or quick-closing valves, can experience residential water hammer.
Experiencing that sudden, jarring bang from your pipes? That’s likely water hammer, a common but annoying plumbing problem. This phenomenon, also called hydraulic shock or pipe banging noise, happens when fast-moving water is abruptly stopped or forced to change direction. Think of it like a sudden stop in traffic – cars pile up, creating a shockwave. In pipes, this shockwave travels back and forth, causing that distinctive banging. It’s not just an annoyance; repeated water hammer can stress your pipes, fittings, and even appliances, potentially leading to leaks and damage over time. Fortunately, reducing water hammer is achievable for most homeowners. This guide will delve into the causes, effects, and most importantly, effective methods for water hammer prevention and elimination of pipe shock, helping you achieve a quiet plumbing system.
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Deciphering the Causes of Pipe Banging Noise
Grasping why water hammer occurs is the first step to eliminating it. It’s all about the momentum of water. When water flows through your pipes, it has momentum. When a valve slams shut suddenly, like a toilet fill valve or a washing machine solenoid valve, that momentum has nowhere to go. The water instantly stops, but the water behind it is still moving. This collision creates a powerful pressure wave that travels back through the pipe.
This pressure wave can bounce off elbows, tees, and the end of the pipe, creating a series of shock waves. These waves can cause significant stress on your plumbing. It’s like hitting a wall – the force travels back.
Here are the primary culprits behind water hammer:
- Quick-Closing Valves: These are the most frequent offenders.
- Toilet fill valves: Especially older diaphragm types.
- Washing machine solenoid valves: They shut off water supply very quickly.
- Dishwasher solenoid valves: Similar to washing machines.
- Single-lever faucets: When turned off quickly.
- Sprinkler system valves: Particularly those with electric solenoids.
- High Water Pressure: If your home’s water pressure is too high (above 80 psi), it exacerbates the effects of even minor flow changes, making water hammer more likely and more severe.
- Loose Pipes: Pipes that aren’t properly secured or strapped can vibrate and bang against framing or other structures when a pressure surge occurs, adding to the noise. This contributes to pipe vibration dampening issues.
- Air in the System: While less common, trapped air pockets can sometimes contribute to the jarring noises associated with water hammer.
The Impact of Water Hammer on Your Home
Beyond the startling noise, water hammer can have detrimental effects on your plumbing system:
- Pipe Damage: Repeated shock waves can weaken pipe joints, leading to leaks. They can also cause pipes to fatigue and crack over time.
- Fixture Damage: The constant jarring can damage the internal components of faucets, toilets, and appliance valves, shortening their lifespan.
- Appliance Issues: Washing machines, dishwashers, and ice makers rely on water valves that can be sensitive to pressure surges. Water hammer can cause these valves to malfunction or fail.
- Loose Fittings: The stress from water hammer can loosen pipe fittings, exacerbating leaks and potentially causing more significant problems.
Strategies for Reducing Water Hammer
Tackling water hammer involves addressing its root causes. The goal is to either slow down the water’s momentum or provide a cushion for the pressure surge. Here are the most effective methods for water hammer prevention.
1. Install a Water Hammer Arrestor (Plumbing Shock Absorber)
This is often the most effective and recommended solution for eliminating water hammer. A water hammer arrestor, also known as a plumbing shock absorber or surge suppressor plumbing, is a small device installed on your plumbing lines to absorb the shock of sudden water stoppage.
How They Work:
Most modern water hammer arrestors use an air cushion. They typically consist of a chamber with a piston or diaphragm that separates the water supply from a pocket of air or gas. When a water hammer event occurs, the sudden pressure surge forces the water into the arrestor, compressing the air cushion. This compression absorbs the energy of the shock wave, preventing it from traveling through the entire pipe system.
Types of Water Hammer Arrestors:
- Piston Type: These are very common and effective. A free-moving piston within a cylinder separates the water from an air charge. When pressure increases, the piston is pushed back, compressing the air.
- Diaphragm Type: Similar to the piston type, but a flexible diaphragm separates the water from the air charge. These are also very effective.
- Air Chamber Type (DIY): While professional arrestors are recommended, you can create a simple air chamber by capping a vertical pipe extension. However, these can lose their air charge over time and require periodic draining of the system to refill.
Where to Install:
Water hammer arrestors are most effective when installed close to the source of the problem, typically near quick-closing valves such as:
- Washing machines: Install on both hot and cold water supply lines.
- Dishwashers: Install on the hot water supply line.
- Toilets: Install on the supply line to the toilet tank.
- Ice Makers: Install on the supply line.
Installation Steps:
- Turn off the main water supply. This is crucial for safety.
- Drain the lines. Open a faucet at the lowest point in your house to relieve pressure and drain the water.
- Locate the nearest tap or fitting to the appliance or valve causing the water hammer.
- Install the arrestor. Thread the arrestor onto the faucet outlet or a tee fitting. Use Teflon tape on the threads for a good seal.
- Turn the water supply back on slowly.
- Check for leaks.
- Test the system by running the appliance or using the faucet.
Table 1: Pros and Cons of Water Hammer Arrestors
| Pros | Cons |
|---|---|
| Highly effective at eliminating noise | Initial purchase cost |
| Prevents pipe damage and leaks | Requires basic plumbing knowledge to install |
| Protects appliances | Might require locating specific shut-off valves |
| Long-lasting (with proper installation) | Can sometimes fail if diaphragm ruptures |
2. Check and Adjust Water Pressure
High water pressure is a significant contributor to water hammer. If your home’s water pressure exceeds 80 psi, it’s a good idea to have it reduced.
How to Check Water Pressure:
You can easily check your home’s water pressure using a simple water pressure gauge that screws onto an outdoor hose bib or an indoor faucet.
- Ensure no water is being used in the house.
- Screw the gauge onto the faucet.
- Open the faucet slowly.
- Read the pressure indicated on the gauge.
Reducing High Water Pressure:
If your pressure is consistently above 80 psi, you should install a Pressure Reducing Valve (PRV) on your main water supply line.
- PRV Location: Typically installed where the main water line enters your home, after the main shut-off valve.
- How it Works: A PRV uses a spring-loaded diaphragm to maintain a consistent downstream pressure, regardless of fluctuations in the upstream pressure.
- Adjustment: Most PRVs can be adjusted to your desired pressure. A typical recommended range for residential plumbing is 50-60 psi.
Installation of a PRV:
- Professional Installation Recommended: While a DIY project for some, installing a PRV correctly involves working with your main water line and can be complex. Hiring a plumber is often the safest and most reliable option.
- Steps (General):
- Turn off the main water supply.
- Drain the line.
- Cut into the main water line and install the PRV using appropriate fittings. Ensure the arrow on the valve indicates the correct flow direction.
- Turn the water supply back on slowly.
- Adjust the PRV to the desired pressure using the adjustment screw.
- Test for leaks.
3. Secure Loose Pipes for Pipe Vibration Dampening
Loose pipes can vibrate against framing, joists, or other pipes during a water hammer event, amplifying the noise and contributing to that unsettling pipe banging noise. Proper pipe support is key to pipe vibration dampening.
How to Secure Pipes:
- Locate the problem pipes: Listen for the noise and try to pinpoint which pipes are vibrating.
- Use pipe straps or hangers: These are readily available at hardware stores.
- Strap Type: U-shaped metal straps with rubber lining are ideal as they cushion the pipe.
- Hanger Type: Suspend pipes from overhead joists using pipe hangers.
- Placement: Install straps or hangers at regular intervals along the pipe run, especially at elbows and turns. Aim for approximately every 4-6 feet for vertical runs and every 8-10 feet for horizontal runs, but adjust based on pipe diameter and material.
- Tighten Securely, But Not Too Tight: The pipe should be held firmly in place without being crushed. A snug fit is sufficient. Over-tightening can actually restrict water flow or stress the pipe.
4. Install Air Chambers (A More Traditional Approach)
Before the advent of modern water hammer arrestors, plumbers would install air chambers as a DIY solution. These are essentially vertical sections of capped pipe installed above the shut-off valve.
How Air Chambers Work:
The idea is that the air trapped in the vertical pipe acts as a cushion. When a pressure surge occurs, the water is forced into the air chamber, compressing the air.
Installation:
- Turn off the water supply and drain the lines.
- Install a tee fitting on the pipe above the valve causing the hammer.
- Thread a capped pipe nipple (typically 18-24 inches long) vertically into the top of the tee.
- Turn the water back on slowly.
Drawbacks of Air Chambers:
- Air Loss: Over time, the air in these chambers can become absorbed into the water or leak out, rendering them ineffective. They often need to be “recharged” by draining the water system periodically.
- Less Effective: They are generally less reliable and less effective than modern water hammer arrestors.
5. Slow Down Valve Operation
For fixtures where you have control over the valve’s operation (like single-lever faucets), simply closing them more slowly can significantly reduce or eliminate water hammer.
- Practice: Make a conscious effort to turn off faucets gently and gradually.
- Levers: For single-lever faucets, avoid slamming the lever shut.
6. Consider Flow Restrictors
In some cases, excessive water flow can contribute to the severity of water hammer. Replacing aerators or showerheads with lower-flow models can help reduce the volume and velocity of water, thereby mitigating the impact.
Troubleshooting Common Water Hammer Scenarios
Let’s look at how to apply these solutions to specific situations.
Washing Machine Water Hammer
This is a very common scenario due to the solenoid valves in washing machines.
- Solution: Install a water hammer arrestor on both the hot and cold water supply lines directly behind the washing machine. These are usually readily available at hardware stores and are designed for this purpose.
Toilet Water Hammer
Often caused by the fill valve in the tank.
- Solution: Install a small water hammer arrestor on the water supply line leading to the toilet tank. Ensure it’s installed vertically and correctly tightened.
Dishwasher Water Hammer
Similar to washing machines, dishwashers have solenoid valves.
- Solution: Install an arrestor on the hot water supply line to the dishwasher.
Faucet Water Hammer
If a specific faucet causes the noise, especially when turned off quickly.
- Solution:
- First, try turning the faucet off more slowly.
- If the problem persists, install a water hammer arrestor on the supply line to that faucet. You might need to turn off the water under the sink and install a tee fitting to accommodate the arrestor.
Maintaining a Quiet Plumbing System
Once you’ve addressed water hammer, you’ll want to keep your plumbing system quiet and protected. Regular maintenance can help prevent future issues.
- Periodic Pressure Checks: Check your home’s water pressure annually, especially if you have a PRV that might need recalibration.
- Inspect Pipe Supports: Occasionally check that your pipes are still securely strapped and that no new areas of looseness have developed.
- Listen for New Noises: Be attentive to any new or returning banging sounds. They could indicate a developing problem or that a previous fix is no longer working effectively.
- Consider Arrestor Longevity: While arrestors are durable, they aren’t permanent. If you notice a return of the water hammer after several years, the arrestor might need replacement.
Frequently Asked Questions (FAQ)
Q1: How much does it cost to fix water hammer?
The cost can vary. Installing a water hammer arrestor typically costs between $10-$30 for the device itself, plus any minor plumbing supplies like Teflon tape. If you hire a plumber, expect to pay $100-$300 depending on your location and the complexity of the installation. Adjusting a PRV might cost $50-$150. Securing loose pipes is relatively inexpensive, costing just a few dollars for straps.
Q2: Is water hammer dangerous?
While the noise is the most immediate concern, prolonged or severe water hammer can indeed be dangerous to your plumbing system. It puts stress on pipes, joints, and appliances, potentially leading to leaks, burst pipes, and costly damage.
Q3: Can I use pipe insulation to stop water hammer?
No, pipe insulation is designed for thermal insulation (keeping water hot or cold) and does not address the pressure surges that cause water hammer.
Q4: Will a water hammer arrestor work on all types of pipes?
Yes, water hammer arrestors are effective on various pipe materials, including copper, PEX, and galvanized steel.
Q5: My washing machine still makes noise after installing arrestors. What else can I do?
Ensure the arrestors are installed correctly, on both hot and cold lines, and are the appropriate type for washing machine use. Double-check that the water pressure isn’t excessively high. If the issue persists, there might be a problem with the washing machine’s internal valves.
Q6: How do I know if I have high water pressure?
You can test your water pressure with a simple gauge that screws onto a faucet. Most homes should have pressure between 40-60 psi, with anything over 80 psi considered too high and potentially damaging.
Q7: What is a plumbing shock absorber?
A plumbing shock absorber is another term for a water hammer arrestor. It’s a device designed to cushion the shock waves caused by sudden changes in water flow.
By following these guidelines and implementing the appropriate solutions, you can effectively stop water hammer, protect your plumbing system, and enjoy a quieter, more peaceful home.