Quick Answer:
If you only hear banging late at night, start by watching and logging when the noise happens for 2–3 nights and check if it lines up with appliance cycles. Attach a hose-bib pressure gauge and leave it overnight; if pressure readings swing between late night and morning, a plumber can confirm the cause and stabilize the system.
Why This Happens
Late-night pipe banging often happens when something in the house cycles at low-usage hours or when the water supply itself changes pressure. Common causes include toilet refills, an ice maker or other automatic water-fed appliance starting or stopping, thermal expansion, loose pipe straps, or changes in municipal supply pressure. If the timing lines up with quiet hours, the noise may be triggered by cycling devices or short-term pressure spikes such as Banging triggered by city pressure changes.
Step-by-Step What to Do
1. Log the exact time for 2–3 nights
- Keep a simple notebook or a notes app and write the exact minute the bang occurs for at least two, preferably three, nights.
- Note any household activity at that time (toilet flushed, dishwasher or laundry finished, someone used a sink, etc.).
2. Check for appliance cycles
- Listen for matches between your log and appliance behavior. Common culprits are toilet refills and ice maker fills. For ice makers, look for a short water fill and valve shutoff that often makes a click or bang; check whether the sound coincides with the times in your log — this is when **Pipes bang when ice maker shuts off** may apply.
- Run a quick test: at a time you expect the noise, watch toilets and appliances for the short cycles that follow a flush or refilling event.
3. Attach a hose-bib pressure gauge overnight
- Buy or borrow a simple pressure gauge that screws onto an outdoor hose spigot (hose-bib). Attach it securely before bedtime.
- Leave it connected overnight and note the reading when the bang happens, if you can check without causing more noise. If you can’t watch in real time, check it first thing in the morning to compare.
- Remove the gauge before freezing temperatures to avoid damage.
4. Compare late-night vs morning readings for swings
- If you could record a reading near the time of a bang and then a morning reading, look for significant differences. A swing of several psi or more can indicate pressure regulation or supply issues.
- If readings show a clear drop or spike overnight, note the pattern exactly — this information is what a plumber needs to confirm and stabilize the system.
What Not to Do
- Don’t repeatedly shut off the home’s main valve nightly as a “test”; if the main valve is stiff or won’t close fully, have a plumber service it—forcing it can create a leak you didn’t have before.
- Don’t hit pipes or appliances to try to “stop” the noise — that can damage fixtures or move things into a worse position.
When to Call a Professional
- Call a plumber if your overnight pressure gauge shows large swings, if you see water leaks, or if the banging continues after you’ve checked appliance cycles and secured loose pipes.
- If the main shutoff valve is stiff, leaks, or won’t operate smoothly, contact a plumber — do not force it.
- A plumber can test system pressure, check the pressure regulator/PRV, install or adjust arrestors or expansion tanks, and secure piping to stop recurring hammering.
Safety Notes
- Turn off water only when you know how to and only for short, necessary tests. Know where the main shutoff is located before you need it in an emergency.
- Remove an overnight gauge if sub-freezing weather could freeze the gauge and spigot.
- If you’re uncomfortable with any step, especially operating the main valve or working on pressurized parts, stop and call a professional.
Common Homeowner Questions
- Why does it only happen at night? Low household use lets small cycles and supply pressure changes be more noticeable, so noises that get drowned out during the day stand out at night.
- Will securing loose straps fix it? Sometimes — loose pipes can cause hammering noises, but if pressure swings or an appliance cycle is the cause, strapping alone won’t stop it.
- Can I leave the pressure gauge attached long-term? No — use it for diagnosis, remove it afterward, and avoid leaving it in freezing weather or where it could be damaged.
For more related articles, see the Pipes Banging After Fixtures Turn Off hub.