Why Does My Home’s Plumbing Make Knocking Noises and How Can It Be Fixed?

It’s late at night, your house is quiet, and then—bang!—you hear it. Somewhere in your walls, your plumbing has decided to start a percussion concert. Knocking, banging, or clanging pipes are not only annoying but can also signal potential problems in your plumbing system that shouldn’t be ignored. Fortunately, understanding the cause can help you find the right fix.

At Golden Rule Plumbing, Heating, Cooling & Electrical, we’ve helped countless Iowa homeowners silence their noisy pipes and restore peace to their homes. Let’s dive into the reasons behind those knocking sounds—and what you can do about them.

1. The Most Common Culprit: Water Hammer

The most frequent cause of banging or knocking in your plumbing system is something called “water hammer.”

Water hammer occurs when a valve (like a faucet or washing machine solenoid) shuts off suddenly, causing the flow of water to stop abruptly. Since water is incompressible, it slams against the closed valve or pipe walls, creating that loud knocking or banging sound.

What Causes Water Hammer:

• Fast-closing valves on modern appliances (dishwashers, washing machines, ice makers)
• Poorly secured pipes that vibrate when water stops
• Worn-out or missing air chambers designed to absorb shock

How to Fix It:

• Install water hammer arrestors: These small devices absorb the shock caused by sudden stops in water flow. They’re typically installed near the problem appliance.
• Secure loose pipes: Use pipe straps or cushioning brackets to keep pipes from moving and rattling.
• Check water pressure: Excessively high pressure (over 60 psi) increases the likelihood of water hammer. A professional plumber can test and regulate your home’s pressure with a pressure-reducing valve if necessary.

2. High Water Pressure Problems

High water pressure might sound like a good thing—it helps with stronger showers, right? But it can also wreak havoc on your plumbing system.

When water pressure is too high, it can cause your pipes to vibrate or bang as the force of the flow exceeds what your plumbing was designed to handle. This can damage fittings, wear out appliances, and make your plumbing noisy.

How to Tell if You Have High Pressure:

• Frequent banging or whistling noises
• Dripping faucets or running toilets
• Shortened lifespan of appliances like dishwashers or water heaters

The Fix:

A licensed plumber can measure your water pressure and, if needed, install a pressure-reducing valve. This not only stops the noise but also protects your pipes and appliances in the long run.

3. Loose or Poorly Secured Pipes

Sometimes, the issue is purely mechanical. If pipes aren’t secured tightly to walls, floors, or joists, the vibration caused by running water can make them rattle or “knock” against framing materials.

This issue is common in older homes or homes that have had partial plumbing work done over the years.

The Fix:

A plumber can:

• Add or replace pipe straps and brackets
• Use rubber or foam padding to cushion the pipes
• Inspect for hidden damage that might have occurred from repeated movement

If the noise seems to come from behind a wall, resist the temptation to open it up yourself. A professional can locate the problem with minimal disruption.

4. Sediment or Air in the Lines

If the noise sounds more like gurgling, sputtering, or clicking, trapped air or sediment buildup may be the problem.

Air in the lines can occur after a water main break or plumbing repair, while sediment buildup—especially in older water heaters or galvanized pipes—can restrict flow and create turbulence that causes noise.

How to Fix It:

• Flush your plumbing system: Turn off the water, open all faucets, then slowly turn the main water supply back on to purge air.
• Drain and flush your water heater: Sediment buildup in the tank can cause knocking sounds when heating. Annual flushing keeps your water heater running quietly and efficiently.
• Call a plumber for persistent issues: If the noise doesn’t go away, professional cleaning or replacement of older pipes might be necessary.

5. Expansion and Contraction of Pipes

When hot water flows through metal pipes, they expand. As they cool, they contract. If your pipes rub against studs or other building materials, you might hear a series of ticking or tapping noises, particularly when using hot water.

The Fix:

Insulate your hot water pipes or add cushioning where they contact framing. This helps minimize the friction and quiets the expansion noises.

When to Call a Professional

While some minor plumbing noises can be managed with DIY fixes, recurring or loud knocking should always be checked by a professional. Ignoring the problem can lead to:

• Damaged valves or fittings
• Burst pipes in severe cases
• Higher water bills from hidden leaks

At Golden Rule Plumbing, Heating, Cooling & Electrical, our licensed plumbers can diagnose the cause quickly and provide lasting solutions—whether that means securing pipes, adjusting pressure, or installing arrestors. We’ll make sure your plumbing system runs safely, quietly, and efficiently.

Preventing Future Plumbing Noises

• Schedule regular plumbing inspections
• Flush your water heater annually
• Keep your home’s water pressure within safe limits
• Replace aging or outdated plumbing components

By keeping up with preventive maintenance, you’ll not only prevent knocking sounds but also extend the life of your plumbing system.

Final Thoughts

Knocking or banging pipes are more than a nuisance—they’re a sign your plumbing system needs attention. With the right diagnosis and fix, you can restore peace to your home and avoid costly repairs later on.

If your pipes are giving you a headache, don’t wait. Contact Golden Rule Plumbing, Heating, Cooling & Electrical today for fast, friendly, and professional plumbing service.