Quick Answer:
After new pipes are installed you may still hear occasional bangs. Often these are pressure changes or water hammer, or a supply-side surge outside your house. Start by logging when the noise happens, listen at the water heater and the main entry to localize it, and compare times with neighbors. If the pattern suggests the problem is on the supply side, a plumber can safely confirm and fix pressure-control components.
Why This Happens
New piping can change how pressure moves in a system. Air pockets, fast valve closures, the thermal expansion of a closed hot-water system, or a faulty pressure regulator can cause sudden pressure surges that make pipes bang. Supply-side events — like city pressure adjustments, nearby pump cycles, or a shared booster system — can also make pipes vibrate or produce repeated knocks even when no faucets are open. For related noise patterns, see Pipes bang when no water is on and Random hammer sounds.
Step-by-Step What to Do
1. Note the time of each bang
Keep a simple log (phone notes or a notepad). Record the exact time, how long it lasts, and whether it sounds like a single knock or a repeating pattern. This record is the most useful thing you can give a plumber or your water utility.
2. Check if it aligns with neighbors or city activity
Ask a nearby neighbor if they hear the same thing at the same times. If the bangs match neighbors, it’s likely a supply-side issue (city mains, pumps, or a shared system) rather than something inside your home.
3. Listen near the water heater and main entry
Walk through the house while the noise is happening. Listen close to the water heater, the main water shutoff, and where the pipe enters the building. Finding the loudest spot helps determine whether the surge originates inside your system or where the service line connects.
4. Do simple pressure observations
- Watch faucets and the pressure at fixtures when the noise happens. Do taps temporarily pulse or change pressure?
- If you have a hose bib, you can attach a pressure gauge or have a plumber read the pressure. High steady pressure (over 80 psi) or rapid pressure spikes can explain banging.
5. Note appliance or system cycles
Check whether the bangs coincide with appliances cycling (well pumps, irrigation controllers, water heaters on demand). If it lines up with a particular cycle, that device or its valve may need adjustment or service.
What Not to Do
- Don’t start opening walls, cutting into ceilings, or removing insulation to chase noise unless a pro confirms a hidden failure—those actions are invasive and may not fix the root cause.
- Don’t disable safety devices (pressure relief valves, expansion tanks, or any control device). They protect the system and your home.
- If bangs continue with no fixtures running, have a plumber evaluate pressure control components rather than attempting major repairs yourself.
When to Call a Professional
Call a licensed plumber if you get repeated bangs that you can’t explain with your log, if you detect fluctuating or high pressure at fixtures, or if the banging correlates with no in-home usage. If your notes and neighbor checks point to the supply side (city main or shared pump), a plumber can safely test pressure, inspect the pressure regulator and expansion tank, and coordinate with the water utility if needed. Don’t delay a call if the banging is frequent or accompanied by visible leaks or loose fittings.
Safety Notes
- Turn off the main shutoff only if you suspect a serious leak or when instructed by a professional. Doing so will stop water but may leave appliances without water protection.
- Never remove or tamper with relief valves or pressure devices—these protect against dangerous pressure build-up.
- When in doubt, stop using potentially affected appliances and let a plumber inspect the system to avoid causing further damage.
Common Homeowner Questions
- Q: Could the new pipes be the only cause?
A: Sometimes; new piping changes flow dynamics, but supply-side pressure and appliances are common contributors. - Q: Will adding air chambers or clips fix it?
A: Temporary fixes can help for light water hammer, but a proper diagnosis is better—pressure issues or faulty regulators need professional correction. - Q: How long should I wait before calling a plumber?
A: If bangs are repeated, unpredictable, or paired with pressure changes or leaks, call a plumber promptly; otherwise keep a log for a few days to spot patterns.
For more related articles, see the Random Banging With No Water Running hub.