Quick Answer:
If your system won’t rebuild pressure after a shutoff, first check for a vacuum lock and make sure you have an open relief or bleed point before you try to repressurize. Work slowly, open a faucet or relief fixture while repressurizing, and watch the pressure gauge. If pressure still won’t return or you see leaks, call a pro.
Why This Happens
- Vacuum lock or trapped air: When piping drains during a shutoff, a vacuum can form and prevent water from flowing back in until air is let in at a high point or a relief point is opened.
- Closed or partially closed valves: A supply valve, check valve, or isolation valve stuck or not fully reopened will block flow.
- Faulty pressure tank, pump, or controller: Mechanical or electrical failures can stop the pump from building pressure.
- Obstruction from debris or sediment: Sediment can clog screens, valves, or small openings after repair work — see **Sediment clogging fixtures post repair** for related issues.
- Relief or air vents closed: If the system has no open bleed point, repressurizing can create lock conditions or damage components.
Step-by-Step What to Do
Preparation: gather tools and isolate safely
- Tools: adjustable wrench, screwdriver, bucket, towels, pressure gauge (if you have one), flashlight.
- Turn off power to any pump before working on valves or fittings.
- Know where the main shutoff, pump switch, and relief/bleed fixtures are located.
1. Visually inspect for obvious problems
- Look for closed valves between the source and the pressure tank or meter.
- Check for visible leaks, broken fittings, or tripped electrical disconnects.
2. Check for vacuum lock
- Open a high or accessible fixture (a sink faucet or hose bib) then try to admit water slowly into the section that won’t pressurize. If water does not flow, a vacuum lock or closed valve is likely.
- Try opening a second fixture at a higher point in the system to allow air to enter so water can displace the vacuum.
3. Open a relief or bleed fixture while repressurizing
- With a faucet or dedicated relief valve open, slowly restore supply or restart the pump. Keep the bleed point open until steady water flow without sputtering appears.
- Open both hot and cold briefly if the problem is inside a branch so air in either line can escape.
- Opening a relief fixture prevents pressure spikes and helps trapped air escape — do this before trying to crank up pressure.
4. Slowly bring pressure back up and observe
- If you have a pressure gauge, raise pressure gradually and watch for proper cut-in/cut-out behavior or stable gauge readings.
- Listen for irregular pump behavior and watch for leaks when lines refill.
5. Flush and inspect fixtures after repressurizing
- Run taps for a minute to clear air and small debris. If you notice unusual taste or smell, consult guidance on **Water smells after plumbing repair**.
- Check aerators and screens at fixtures for sediment that could indicate debris moved during repressurization.
What Not to Do
- Don’t repressurize without a bleed point. Repressurizing a sealed line can create vacuum or pressure damage and trap air.
- Don’t rapidly crank the system pressure up to full while lines are air-filled.
- Don’t work on pressurized components without turning off electrical power to pumps and taking proper safety measures.
When to Call a Professional
- Pressure will not build after you’ve opened a bleed point and followed the steps above.
- You see continuous leaks, a failing pressure tank, or pump cycling on and off rapidly.
- There are signs of internal valve failure, damaged piping, or you’re uncomfortable working with the pump and electrical controls.
Safety Notes
- Always turn off electrical power to pumps before working on valves, fittings, or the pressure tank to avoid electrocution or accidental pump start.
- Relieve pressure at a faucet or designated relief valve before loosening fittings to avoid sprays of water.
- Hot water lines can cause burns; let water cool or isolate hot water before opening fixtures.
Common Homeowner Questions
- Why is there no water after I open the main shutoff? Air locks, closed valves, or a stuck check valve usually block flow; open a bleed point and let air escape.
- Will running taps clear trapped air? Yes—running an open faucet while repressurizing usually lets air escape and restores steady flow.
- Can I just run the pump until pressure returns? No—running without an open bleed can worsen air locks or damage the pump; open a relief fixture first.