Water Hammer: How to Stop Banging Pipes and Protect Your Plumbing System
If you’ve ever turned off a faucet or appliance and heard a loud banging or thudding sound echo through your pipes, you’ve experienced water hammer. This common plumbing issue might sound harmless, but over time, it can damage your pipes, loosen joints, and cause leaks or even burst lines.
At Speedee Drains Plumbing Pros, serving Orange County and Los Angeles County, we specialize in residential and commercial plumbing, including leak detection, drain cleaning, hydro jetting, and water line repair. In this guide, we’ll explain what causes water hammer, how to fix it, and how to prevent it from coming back.
1. What Is Water Hammer?
Water hammer — also known as hydraulic shock — occurs when fast-moving water suddenly stops or changes direction. The momentum of that moving water creates a shockwave inside your pipes, resulting in a loud banging or knocking noise.
Over time, these pressure surges can:
- Loosen pipe fittings.
- Damage valves and joints.
- Lead to leaks in copper or PEX pipes.
- Cause premature wear on appliances like dishwashers and washing machines.
In other words, that loud thud is your plumbing system under stress.
2. Common Causes of Water Hammer
1. Fast-Closing Valves
Modern appliances like dishwashers and washing machines use quick-closing solenoid valves. When these shut off suddenly, the rapid stop in water flow sends a shockwave through the pipes.
2. High Water Pressure
Excessive water pressure is one of the most common causes of water hammer. Ideally, your home’s pressure should be between 40–60 PSI. Anything higher increases stress on pipes.
3. Loose or Unsecured Pipes
If your pipes aren’t properly anchored inside the walls or crawl space, they can rattle or bang when water pressure shifts.
4. Air Chamber Problems
Older homes may have air chambers installed near valves to absorb pressure surges. Over time, these can fill with water, losing their ability to cushion the flow.
5. Long or Narrow Pipe Runs
Water traveling through long sections of pipe at high velocity has more energy to release when stopped, intensifying the hammer effect.
3. How to Identify Water Hammer
The sound itself is usually unmistakable — a loud bang or thud immediately after shutting off a faucet or appliance.
Other signs include:
- Pipes vibrating or rattling behind walls.
- Minor leaks forming at joints or connections.
- Faucet handles that jerk slightly when turned off.
- Appliances that make loud noises when filling or draining.
If the banging persists even after simple adjustments, the issue likely lies deeper within the plumbing system.
4. Step-by-Step Ways to Fix Water Hammer
Step 1: Turn Off the Water Supply and Drain the Pipes
- Shut off your home’s main water valve.
- Open all faucets (starting upstairs and moving down) to drain the lines completely.
- Flush all toilets to clear any remaining water.
- Once drained, close all faucets and slowly turn the main valve back on.
This process can restore trapped air cushions in older plumbing systems that rely on air pockets to absorb shock.
Step 2: Secure Loose Pipes
- Inspect accessible pipes in your basement, crawl space, or under sinks.
- Add pipe straps or padded supports where necessary to hold pipes firmly in place.
- Use rubber pipe clamps to minimize vibration.
Pro Tip: Avoid using metal-on-metal fasteners — they amplify noise rather than reduce it.
Step 3: Install Water Hammer Arrestors
If draining the system doesn’t help, installing water hammer arrestors is the next step.
These small, air-filled chambers absorb shock and prevent pressure surges. They can be:
- Inline arrestors: Installed directly behind washing machines, dishwashers, or ice makers.
- Whole-house arrestors: Installed near the main water supply to protect the entire plumbing system.
Water hammer arrestors are one of the most effective long-term solutions.
Step 4: Check and Adjust Water Pressure
- Attach a pressure gauge to an outdoor spigot or laundry faucet.
- If pressure exceeds 60 PSI, you’ll need to adjust your pressure-reducing valve (PRV).
- If your home doesn’t have a PRV, consider installing one — it protects pipes and appliances from excess stress.
High water pressure not only causes water hammer but also increases the risk of leaks, fixture damage, and wasted water.
Step 5: Bleed Air from Newer Plumbing Systems
Some modern systems are sealed, which means trapped air pockets can cause hammering sounds.
- Turn off the water supply.
- Open all fixtures one by one, starting with the highest point in the house.
- Close them in reverse order once water runs smoothly without sputtering.
Step 6: Inspect Appliance Valves
Quick-closing solenoid valves in appliances are notorious for creating hammering effects.
- Check if your dishwasher or washing machine has built-in arrestors — if not, have them installed.
- Ensure hoses and fittings are tight and secure.
5. Preventing Water Hammer
- Monitor water pressure: Keep it between 40–60 PSI.
- Install water hammer arrestors: Especially on modern appliances.
- Replace old air chambers: Over time, they fill with water and stop working.
- Secure new plumbing installations: Use proper clamps and cushioning to prevent pipe movement.
- Schedule annual plumbing inspections: A licensed plumber can check for pressure imbalances and early signs of damage.
6. When to Call a Professional
While minor water hammer can often be fixed with DIY adjustments, persistent or severe banging requires professional help.
Call a plumber if:
- You’ve tried draining your system and securing pipes with no improvement.
- Water hammer occurs throughout the home, not just near one fixture.
- You notice leaks, water stains, or loose fittings near pipes.
- Your water pressure is consistently above 80 PSI.
At Speedee Drains Plumbing Pros, we use advanced diagnostic tools to measure water pressure, inspect pipe integrity, and install custom water hammer arrestor systems that eliminate the problem at its source.
7. Commercial Plumbing and Water Hammer
In commercial buildings, water hammer is often caused by high-volume water systems and automatic equipment that shut off water suddenly.
Examples include:
- Commercial dishwashers
- Industrial washing machines
- Irrigation control systems
Ignoring water hammer in commercial settings can lead to major pipe failures, costly water damage, and lost business time.
Our team offers pressure regulation, line stabilization, and hydro jetting services to protect commercial plumbing systems from long-term damage.
Final Thoughts
Water hammer may start as a simple noise, but it’s your plumbing’s way of warning you that something isn’t right. The repeated shockwaves can loosen joints, cause leaks, and even burst pipes if ignored. By identifying the cause — whether it’s high water pressure, loose pipes, or lack of arrestors — you can stop the banging and extend the lifespan of your plumbing system.
At Speedee Drains Plumbing Pros, we proudly serve Orange County and Los Angeles County with expert residential and commercial plumbing services, including water hammer prevention, leak detection, water line repair, hydro jetting, and full system maintenance. Whether your pipes are bangin