Quick Answer:
If downstairs fixtures work and upstairs does not, the problem is usually a restriction or a shutoff on the riser that feeds the upper floor, not a city-wide outage. Start by comparing a working downstairs hose bib to an upstairs sink, confirm upstairs stops are open, check the valve feeding the riser for partial closure, and if your plumbing is galvanized consider internal scaling. If you have a booster or pressure tank, make sure it is powered and functioning.
Why This Happens
Most homes split supply lines into lower and upper branches (risers). A local shutoff, a partially closed feed valve, or an internal restriction on the riser will cut flow only to the upstairs fixtures. Air problems or a main supply interruption usually affect the whole house at once. For example, true air issues tend to produce slurping or sputtering at several taps — see Air in all lines after outage for that scenario. If the street or meter were the culprit you would likely see loss downstairs too, or the water meter would indicate no flow — if the meter shows flow but the house still has no upstairs water, that points to a localized restriction or valve issue, as in House lost water but meter shows flow.
Step-by-Step What to Do
1. Compare a downstairs hose bib to an upstairs sink
- Turn on an outdoor hose bib or a downstairs laundry sink and note pressure/flow.
- Immediately run the upstairs sink or shower and compare. If downstairs is normal and upstairs is low or zero, the problem is isolated to the riser or upstairs stops.
2. Verify upstairs stops are open
- Locate isolation stops for each upstairs fixture—shutoff valves are often under sinks, behind access panels, or near toilets.
- Make sure each stop is fully open (turn counterclockwise until it stops). Partially closed fixture stops commonly get overlooked.
3. Check the valve feeding the riser
- Find the main vertical riser or the manifold feeding the upstairs. This is often near the water heater, basement ceiling, or utility closet.
- Confirm any riser shutoff is fully open. A partially closed gate or ball valve can produce the “downstairs OK, upstairs off” split.
- If the valve is stiff, do not force it—note its position and call a plumber if it won’t move without excessive effort.
4. Consider galvanized piping and internal scaling
- Homes with old galvanized iron piping can develop heavy internal scale that narrows the riser and reduces flow upstairs.
- If valves are confirmed open and the riser still won’t deliver, scaling is a likely cause. This typically requires professional assessment—cleaning or replacement of the pipe may be necessary.
5. If you have a booster or pressure tank, confirm it’s powered and primed
- Check the pump breaker or fuse and a visible power switch on the booster. Reset breakers if tripped.
- Listen for the pump running when a tap is opened. If it doesn’t start, or it runs but doesn’t build pressure, the pump or tank may be faulty.
- For pressure tanks, check the air charge only with the tank isolated and using proper instructions—if unsure, call a technician.
6. Gather information before calling for help
- Note which fixtures are affected, any sounds (hissing, banging), whether the meter shows flow, and whether breakers tripped.
- Photograph valve positions or the piping if possible—this helps a pro diagnose faster.
What Not to Do
- Don’t assume upstairs loss is ‘air’—a closed stop or riser restriction is more common.
- Don’t force a stuck valve; you can break the handle or damage the valve seat and create a worse problem.
- Don’t try aggressive chemical treatments in a pressurized system without professional guidance—these can damage pipes or create safety hazards.
When to Call a Professional
- You cannot find or open the riser valve or isolation stops.
- There is suspected internal scaling, corrosion, or a hard-to-access blocked riser.
- The booster pump or pressure tank shows electrical faults, runs continuously, or will not build pressure.
- Any sign of leaks, water damage, or if turning valves creates more water loss or noise you don’t understand.
Safety Notes
- Turn off electrical power before touching pumps or electrical controls. If unsure, switch off the breaker and call an electrician or plumber.
- When checking valves in tight spaces, watch for sharp edges, insulation, and hot surfaces near water heaters.
- If you suspect a large hidden leak, shut off the main water and contact a professional to avoid flooding or structural damage.
Common Homeowner Questions
- Q: Could frozen pipes cause upstairs-only loss?
A: Yes in cold climates if the upstairs branch is exposed; check for cold spots and warmth in the pipe area. - Q: Will opening the main valve fix it?
A: Only if the main or riser valve is partly closed; if the riser is scaled or a pump is dead, opening the main won’t restore flow upstairs. - Q: How long should I wait before calling a plumber?
A: If basic checks (stops, riser valve, pump power) don’t fix it within 15–30 minutes, call a professional—especially if you suspect corrosion, a stuck valve, or pump failure.