Quick Answer:
If water flow stops for a moment and then returns, the most common cause is a temporary drop in system pressure rather than a single faucet problem. Start by watching the whole system, install a gauge with max-needle to record the worst dips, and try to correlate pressure drops with likely triggers before opening or replacing fixtures.
Why This Happens
Brief interruptions in flow are usually pressure events. Possible causes include:
- Utility main work, hydrant flushing, or sudden demand in the neighborhood.
- Automatic systems kicking on or off—irrigation controllers, well pumps, or booster pumps.
- Pressure-reducing valve (PRV) cycling or a sticking PRV that briefly closes.
- Air pockets or partial blockages that temporarily restrict flow until pressure equalizes.
- Weather-related effects such as storms or power blips that affect pumps or municipal systems.
If the pattern is hard to spot, track events and compare them to local activity. For broader or pattern-free problems see Intermittent pressure loss for more context.
Step-by-Step What to Do
1. Observe and log the problem
- Note times when the flow stops and resumes. Record the duration and which fixtures are affected.
- Look for nearby events: irrigation cycles, storm times, trash pickup, or loud water main work outside.
2. Install a gauge with max-needle
- Fit a simple pressure gauge at the house main or an accessible hose bib. Use one with a max-needle (a marker that stays at the highest or lowest point) so you can see brief dips after the fact.
- Leave it in place through a few cycles (several days) so short events are captured.
3. Correlate pressure drops to specific triggers
- Compare your log to known triggers: irrigation runs, storm times, PRV cycles, or pump starts. If dips match those events, you’ve likely found the cause.
- Note if drops happen during or right after neighbor/municipal activity—this points upstream to the utility rather than your plumbing.
4. Isolate upstream vs downstream causes
- To isolate upstream vs downstream causes, shut the house shutoff valve (inside) and open an outside hose bib. If pressure still dips at the meter or outside connection, the issue is upstream (utility or main).
- If dips stop when the main is closed, the problem is inside your plumbing—check PRVs, pressure tanks, or large appliances starting on/off.
- Check the meter: when the house is shut, the meter should read no flow. Any unexpected flow there suggests a leak or meter-side event.
5. Check common internal causes
- Inspect PRV operation and the pressure tank (if on a well). Short pump cycles or a failing tank air charge cause rapid pressure changes.
- Look at irrigation controllers and timed valves—some systems open briefly and draw a lot of water.
6. Next actions based on findings
- If dips are upstream, contact the water utility and provide your gauge log.
- If inside and tied to a pump or PRV, consider a professional check of the pump control, pressure switch, or PRV settings.
- Keep the gauge in place until you’ve confirmed stability or a pattern.
What Not to Do
- Do not assume intermittent loss is a fixture issue—track system-wide behavior first.
- Do not remove or tamper with the water meter or utility-owned equipment yourself.
- Do not make large adjustments to PRVs or pump controls without understanding the system; that can create unsafe pressures or damage appliances.
When to Call a Professional
- Persistent or worsening interruptions after you’ve logged data and isolated the issue.
- Rapid pump cycling, loss of pressure at the meter, or visible leaks once pressure returns.
- If you suspect a failing pressure tank, damaged PRV, or an electrical issue with a pump.
Safety Notes
- Turn off power to pumps before inspecting electrical components. If you’re unsure, call a licensed technician.
- Avoid working on utility-owned equipment (meter, curb stop); contact the utility instead.
- Use eye protection and gloves when accessing outdoor valves and hose bibs. Open any shutoffs slowly to avoid water hammer.
Common Homeowner Questions
- Pressure flickers during showers — Is that related?
Short answer: Yes, shower flickers are often the same pressure events; test with a gauge and log times to see if they match other drops. - Could a single appliance cause this?
Short answer: Sometimes—large timed systems like irrigation can, but confirm with a system-wide check before blaming a fixture. - How long should I monitor before calling someone?
Short answer: Keep the gauge and a simple log for 48–72 hours or until you see a clear pattern or repeated long interruptions.
Related Articles
If you’re troubleshooting a similar symptom, these guides may help:
For the full directory, see Intermittent Pressure Loss Events.