Slow refill after PRV replacement

Slow refill after pressure reducing valve replacement.

Quick Answer:

If toilet refills more slowly after a pressure-reducing valve (PRV) replacement, don’t panic. First check the PRV outlet pressure and allow the system to stabilize for a few hours. If pressure is set too low or a shutoff valve or supply line is partially closed or clogged, the refill will be slow. Verify settings and confirm the refill rate improves after stabilization before replacing parts or calling a plumber.

Why This Happens

  • PRVs reduce house water pressure to a set outlet value. If the new valve was set lower than the old one, every fixture sees less pressure and some toilets refill noticeably slower.
  • After a change, the system can take time to stabilize—air pockets or small debris dislodged during work can temporarily reduce flow.
  • Partial closures at the main shutoff or toilet supply, or debris in the supply line or fill valve, can magnify the effect of a lower PRV setting.
  • If the symptom appears only at quiet times, see Tank refills slowly when house quiet. If the problem gets worse, check Slow refill worsens over time.

Step-by-Step What to Do

1. Check the PRV outlet pressure

  • Locate the PRV (usually near the main shutoff). Use a water pressure gauge on an exterior hose bib or washing machine bib downstream of the PRV.
  • Normal household outlet pressure is often 50–60 psi; many installers set PRVs to 50 psi or lower. If the reading is well below your previous setting, increase it a bit and retest.

2. Let the system stabilize and confirm refill rate

  • After any PRV adjustment, wait 30–60 minutes for pressure to settle. Run a few fixtures to help clear air or loose debris.
  • Flush the toilet once or twice and measure how long the tank takes to refill. Confirm the refill rate improves after stabilization before making other changes.

3. Check shutoff and supply hardware at the toilet

  • Make sure the toilet’s angle stop (supply shutoff) is fully open.
  • Inspect the supply line for kinks or visible damage. If you removed any fittings during the PRV job, check they are reassembled correctly.

4. Inspect the toilet fill valve

  • Debris can clog the fill valve screen. If the fill is slow even with adequate house pressure, consider cleaning or replacing the fill valve per the manufacturer’s instructions.

5. Re-adjust PRV if needed and re-test

  • Make small PRV adjustments—about 5 psi at a time—and recheck downstream pressure and tank refill each time.
  • Aiming for a moderate pressure that balances flow and fixture safety is better than maximizing pressure.

6. If flow is still poor, look for sediment or a damaged valve

  • Mineral buildup or a defective PRV can limit flow even at correct pressure. If you suspect internal blockage, a professional inspection is reasonable.

What Not to Do

  • Don’t assume PRV replacement can’t affect toilets—pressure settings matter. A lower outlet setting will reduce fixture flow.
  • Don’t immediately replace the toilet or fill valve without verifying house pressure and supply valves first.
  • Don’t hesitate to involve a professional if you can’t identify the cause or if adjustments don’t restore adequate refill — if refill is inadequate, a plumber is appropriate.

When to Call a Professional

  • You’ve confirmed the PRV outlet pressure is set correctly but flow is still weak at multiple fixtures.
  • Adjusting the PRV or inspecting the valve requires tools or skills you’re not comfortable with.
  • There are signs of a failing PRV (noisy operation, unpredictable pressure swings) or you suspect internal blockage or damage.

Safety Notes

  • Turn off the main water supply before doing any PRV disassembly. Relieve pressure by opening a faucet first.
  • Make small pressure adjustments slowly; don’t over-tighten PRV adjustment screws or fittings.
  • If you are unsure how to test pressure safely, ask a qualified plumber. Working on the main water system can cause flooding if done incorrectly.

Common Homeowner Questions

  • Why did my toilet slow down right after the PRV was changed? A new PRV may be set to a lower outlet pressure or have temporary debris; check outlet pressure and let the system stabilize.
  • How long should I wait to see if the refill improves? Wait 30–60 minutes after adjusting the PRV and run a few fixtures; that usually clears air and loose debris so you can retest.
  • Can I fix this without a plumber? Often yes—by checking outlet pressure, opening shutoffs fully, and clearing the fill valve screen—but call a plumber if pressure is correct and flow is still poor.

For more related articles, see the nan hub.

More posts