Quick Answer:
When water comes back after an outage but flows weakly everywhere, it’s usually grit, air, or a partially closed control (meter, main, or PRV) limiting flow. Start by flushing a tub spout for 5–10 minutes to clear debris, clean faucet aerators and shower heads, and check filters and valves. If pressure still stays low, verify the PRV under flow conditions before replacing it.
Why This Happens
During an outage or nearby work, dirt and small particles enter the pipes. Those particles tend to lodge in small openings: aerators, shower nozzles, refrigerator lines, softener and fridge filters, and in pressure-reducing valves (PRVs). Air pockets and partially closed valves also reduce flow. If neighbors or the water company worked on supply lines, flow patterns can change temporarily — think of the situation described in Water supply lost after neighbor repair.
Step-by-Step What to Do
1. Re-check the main and meter valves
- Confirm the shutoff at your meter and the house main are fully open. Turn them fully counterclockwise until they stop. Small partial closures can look open but restrict flow.
2. Flush a tub or laundry spout 5–10 minutes
- Run one large tub spout or a hose bib for 5–10 minutes. This pushes grit through the branch lines and can clear debris that’s choking faucets and the PRV.
- Use a bathtub or laundry tub because they have larger openings and better flow than a sink.
3. Clean aerators and shower heads
- Unscrew faucet aerators and soak briefly in vinegar if mineral deposit is suspected, then rinse. For shower heads, remove and flush from the inlet and out the nozzles. Small particles often clog these first.
4. Check fridge and softener filters
- Inspect inline filters for the refrigerator water dispenser/ice maker and your water softener or whole-house filters. Replace or rinse their cartridges if they’re clogged.
5. Verify the PRV under flow
- Many homeowners check PRV pressure statically (no flow). A PRV can read normal pressure when idle but drop under flow if damaged or clogged. With a fixture running, check the PRV setpoint or have a pressure gauge on while water is flowing to see the real under-flow setting.
- Do not assume a static reading proves the valve is fine.
6. Test fixtures and compare
- After flushing and cleaning, test several fixtures at once (shower, kitchen, outside). If outside spigots have good flow while inside is weak, suspect a local restriction like a filter or a stuck diverter.
- If only one side of a fixture is affected, review issues like a stuck cartridge or closed stop — situations similar to Water off only on cold or hot side.
What Not to Do
- Don’t replace the PRV before flushing debris from the outage—new parts clog fast.
- Don’t open a PRV or attempt major valve work if you’re unsure; replacing parts or adjusting without verifying flow can waste money and cause more clogging.
- Don’t ignore the meter/main; assuming they are fully open when they’re not leads to unnecessary parts replacement.
When to Call a Professional
- Low pressure persists after thorough flushing, aerator cleaning, and filter checks.
- You suspect the PRV is failing under flow, or the PRV adjustment does not change flowing pressure.
- There are signs of a hidden leak, sudden drop in pressure with no visible cause, or you’re uncomfortable working on valves or filters.
Safety Notes
- Turn off water at the main before removing or replacing any filters or cartridge parts that require a shutoff.
- Wear gloves and eye protection when cleaning fixtures to avoid contact with debris or chemicals (like vinegar or descaling solutions).
- Avoid using power tools on plumbing unless you know how to protect nearby fixtures and pipes from damage.
Common Homeowner Questions
- Why did pressure drop right after service was restored?
Debris and air enter the system during outages; they settle in narrow openings and reduce flow. - How long should I flush a tub?
Run a tub spout for 5–10 minutes to push most grit out of branch lines. - When is a PRV actually the problem?
When pressure is fine at rest but falls dramatically under flow, or when you’ve removed debris and cleaned filters and the issue remains.
For more related articles, see the Whole-House Water Supply Interruption hub.