Quick Answer:
When the city shuts off water, air can get trapped in your plumbing. Open the highest and lowest fixtures, then bleed your lines by running faucets and flushing toilets until the flow is steady. If sputtering or loud knocks continue after you’ve bled the system, call a plumber.
Why This Happens
City shutoffs depressurize the supply line to your house. When water pressure drops, air from the service line or from pockets inside the pipes moves into the system. That air can cause sputtering at faucets, short bursts from showers, or noisy pipes. If the curb stop or main was turned quickly, you may also notice banging pipes or a sudden water pressure change as the line repressurizes.
Step-by-Step What to Do
1. Open the highest fixture
- Go to the top floor and open an upstairs faucet fully. If you don’t have an upstairs, pick the highest hose bib or shower head.
- This gives trapped air a path to escape toward the top of the system.
2. Open the lowest fixture
- Open a lowest-level fixture—usually a basement hose bib, a laundry tub, or a first-floor sink—fully. If you have a floor drain with a hose hookup, use that.
- Opening both high and low creates a flow path through the whole house so air can flush out.
3. Bleed each line
- Start at the highest opened fixture and work down. Open one faucet at a time and let it run until the stream is solid (no sputtering).
- Flush each toilet once or twice to clear the traps and pipes connected to that branch.
- Close fixtures only after the flow is steady. Repeat if new air appears.
4. Check appliances and fixtures
- Run the dishwasher and washing machine through a short cycle to clear air from their supply lines.
- Turn on outdoor hose bibs briefly to clear the service line if present.
5. Monitor for recurring symptoms
- After bleeding, watch for continuing sputter, knocks, or drops in pressure. If these persist, the system may need professional attention.
What Not to Do
- Do not assume pipe rupture — air in the system is common after a shutoff and usually not a sign of a broken pipe.
- Do not open the curb stop or main valve unless you know how; turning it quickly can make air problems or pressure spikes worse.
- Do not use excessive force on fixtures or fittings to stop noise; that can damage connections.
When to Call a Professional
- Persistent knocking or hammering after bleeding the lines.
- Continuous low pressure or no steady flow at multiple fixtures.
- Visible leaks, wet spots, or signs of pipe failure.
- Any concern about the curb stop, municipal meter, or complex plumbing systems.
Safety Notes
- Turn off electrical devices near fixtures before working around standing water to avoid shocks.
- Be careful of slippery floors when flushing and running multiple fixtures.
- If you must access a meter pit or curb stop outdoors, watch for traffic and avoid digging or tampering with buried components.
Common Homeowner Questions
- How long should I run faucets to clear air?
Run each faucet until the flow is steady—usually a minute or two per fixture. - Will air damage my pipes?
Air itself rarely damages pipes, but repeated loud banging may loosen joints and should be checked. - Can I repressurize the system myself?
If you only open indoor fixtures as described, yes; don’t operate the curb stop or mains unless you are experienced.
For more related articles, see the Curb Stop & Meter Valve Problems hub.