What’s Causing That Strange Sound in Your Pipes? Understanding Water Hammer

Ever heard a loud banging noise right after turning off a tap or when your washing machine finishes filling? That unsettling thump isn’t just annoying—it might be a sign of a plumbing issue called water hammer.

If you’re a homeowner in Toronto or anywhere in the GTA, chances are your plumbing has been under pressure—literally. Old piping, high water pressure, or even newer high-efficiency appliances can cause water hammer. Left unchecked, it can damage your pipes, fixtures, and even your foundation.

In this guide, we’ll break down what water hammer is, why it happens, how to fix it, and when it’s time to call in the pros. Our goal is to help you recognize and solve water hammer problems before they lead to costly plumbing repairs or emergencies.

1. What Is Water Hammer?

Water hammer is a plumbing term for hydraulic shock—a pressure surge that occurs when water suddenly stops or changes direction. When a valve shuts off quickly, the rushing water has nowhere to go, causing the pressure wave to bounce back through the pipe. That’s the bang or knocking sound you hear.

Common Scenarios:

• Toilet refilling after a flush

• Washing machines and dishwashers shutting off quickly

• Faucets being turned off abruptly

The pressure spike can shake pipes, loosen joints, and even crack older piping. Modern homes sometimes have air chambers or water hammer arrestors to absorb the shock, but these components can fail or wear down over time.

Homes in Toronto's older neighbourhoods are especially prone to water hammer due to aging copper or galvanized steel pipes that lack proper anchoring and up-to-date fittings.

2. Common Causes of Banging or Knocking Pipes

Several issues can contribute to water hammer, including:

🌀 Quick-Closing Valves

Appliances like dishwashers, washing machines, and even modern faucets shut water off fast, increasing the chance of water hammer. This abrupt stop of water flow leads to sudden pressure buildup.

💦 High Water Pressure

Many homes in Toronto and surrounding areas have incoming water pressure above 80 PSI—well above the safe range of 40–60 PSI. High pressure intensifies water hammer and places unnecessary strain on all plumbing components.

🔧 Loose Pipes

Pipes that aren’t anchored properly in walls or ceilings can shake and bang against surrounding structures when pressurized water suddenly stops. This is especially common in basements, behind laundry rooms, and under kitchen floors.

🪫 Air Chambers Filled with Water

Older homes may use vertical air chambers to absorb shock waves. Over time, these chambers can fill with water and stop functioning, turning each pressure surge into a loud clatter.

🛠️ Worn-out Valves or Fixtures

Old or faulty shut-off valves may not close gently. Some may close too quickly or unevenly, creating the ideal conditions for water hammer.

Our plumbing inspection services in Toronto can help pinpoint the exact cause and recommend the right solution based on your home’s system.

3. Is Water Hammer Dangerous?

Yes—especially if left unresolved.

Water hammer might seem like just an irritating sound, but the long-term effects can be costly and dangerous.

Risks of Water Hammer:

• Pipe ruptures and slab leaks

• Damage to water heater fittings and internal parts

• Cracked solder joints or burst PEX fittings

• Reduced appliance lifespan (dishwashers, washers)

You may also experience water damage, mold growth, or even flooding if the pipe damage escalates. We’ve seen homes in Toronto's west end suffer ceiling damage from a hidden pipe crack caused by months of untreated water hammer.

When water hammer noise becomes more frequent, louder, or leads to visible water issues, it’s time to contact a professional. Our drain and pipe repair team in Toronto handles these cases daily and can repair damage before it worsens.

4. How to Fix Water Hammer (DIY & Professional Solutions)

🧰 DIY Fixes You Can Try:

Drain and Refill Your Plumbing System
This can restore air chambers that have filled with water.

• Shut off the main water valve

• Open all taps (starting from the top floor down to the basement)

• Wait until water fully drains from the system

• Close taps and slowly turn the water back on

Secure Loose Pipes

• Use brackets, clips, or foam pipe insulation to reduce vibration

• Check basement ceilings or behind accessible panels

Install Faucet Aerators

• Reduce flow rate to minimize pressure surges at fixtures

Check Your Water Pressure

• Attach a gauge to your outdoor hose bib

• If it reads above 70–80 PSI, it’s time to install a pressure-reducing valve

🛠️ Professional Solutions from Anta Plumbing:

Install Water Hammer Arrestors
We install these spring-loaded devices behind appliances or at high-risk fixtures to absorb pressure spikes.

Reconfigure Problem Piping
Older homes often need pipes re-anchored or relocated for optimal performance.

Install Pressure-Reducing Valves (PRV)
Essential in high-pressure neighbourhoods; helps extend the life of your plumbing system.

Use a Camera Inspection for Diagnosis
Our CCTV drain camera inspection reveals internal issues like collapsed pipes, sediment buildup, or loose fittings.

In many cases, we combine two or more solutions to fully address water hammer and protect your plumbing long-term.

5. Preventing Future Water Hammer

Once you've solved the issue, it’s smart to keep your plumbing system in peak shape:

• Schedule Annual Inspections: Especially in homes over 20 years old

• Install PRVs where needed: Prevents water pressure surges year-round

• Replace old shut-off valves: Especially for washers, dishwashers, and ice makers

• Add arrestors during home upgrades: Ideal for retrofits and kitchen or laundry renovations

Our renovation plumbing services in Toronto include preventive planning for quiet, efficient water lines.

6. Why Choose Anta Plumbing in Toronto?

Anta Plumbing has been solving water hammer problems for over 15 years. From downtown Toronto to Oakville, our team is known for fast, reliable, and respectful service.

Why Homeowners Trust Us:

• Licensed, insured, and certified for all types of plumbing repairs

• 24/7 emergency response for urgent water hammer fixes

• Experts in both residential and commercial plumbing systems

• High-quality parts, arrestors, and pressure control systems

• Transparent pricing with detailed estimates

Our technicians are familiar with Toronto’s older neighbourhoods and unique building code requirements, so we always get the job done right the first time.

Need help today? Contact Anta Plumbing now to inspect and fix noisy pipes.

Final Thoughts

That knocking or banging sound in your walls is more than just a nuisance—it’s your plumbing crying for help. Whether it’s a simple fix like draining the air chambers or something that needs professional intervention, understanding water hammer is the first step toward solving it.

Call us today at 416-231-3331 or book a plumbing inspection online.

We’ll silence your pipes and protect your home with professional, fast, and code-compliant service.