Order summary
If one fixture is weak, look at that fixture: aerator, cartridge or supply valve. If one floor or one side is weak, look at the pipes feeding it. When the whole house runs weak, our first suspects are the main valve, the water service and any pressure-reducing valve. If both hot and cold are weak, it is a supply issue; if only hot, look at the water heater.
Numbered steps
- Check every tap. Run cold, then hot, at each sink, tub and shower. Note which are weak.
- Clean the aerator. On a weak faucet, unscrew the tip and rinse out any grit or scale. Toronto's moderately hard water builds scale in aerators and shower heads.
- Check under-sink valves. Make sure the stop valves are fully open. Someone may have half-closed one during a repair.
- Check the main shut-off. A gate valve that was not fully reopened after a repair can choke the whole house.
- Look for a pressure-reducing valve. Some homes have one near the meter. It can fail or be set too low.
- Ask a neighbour. If the street is low too, it may be a city issue. Toronto Water can be reached through 311.
| Where it is weak | Likely cause |
|---|---|
| One faucet or shower | Clogged aerator, shower head or cartridge |
| Hot side only | Water heater valve, sediment, or hot line corrosion |
| Upper floor only | Undersized or corroded pipes, too many fixtures on one line |
| Whole house | Main valve, water service, pressure-reducing valve |
Plumber's tip: Galvanized steel pipe narrows inside as it rusts. Many older North York houses still have some. If your house has grey threaded pipes, they may be the cause.
Errors we see on site
- Buying a new shower head before cleaning the old one.
- Opening the main valve only part way after a repair.
- Ignoring a sudden drop. A gradual decline is usually scale or corrosion; a sudden one can mean a leak or a failed valve.
- Adding a booster pump without finding out why pressure is low. That treats the symptom, not the cause.
Write down what you found before you call. A note such as "all upstairs taps weak, basement fine, started gradually" helps us bring the right parts and saves time on the visit. Include the decade the house went up, and whether any plumbing has been changed recently.
When the desk should come out
Call if pressure is low across the house and the main valve is fully open, if you suspect galvanized piping, if the pressure dropped suddenly, or if you hear water running when nothing is on. That last one points to a leak; our leak detection page explains how we find hidden ones.
A stiff or failing main valve can be replaced; see main shut-off valve replacement. Where old pipes are the problem, repiping is the lasting fix.
Book on (365) 517-5705.
Quick checklist
- Check pressure at several taps
- Clean aerators and showerheads
- Confirm the main valve is fully open
Your questions on this one
Can a water softener cause low pressure?
An undersized or clogged one can. Try the bypass valve; if pressure returns, the softener is the cause.
Why is pressure fine downstairs but weak upstairs?
Height costs some pressure, but a big difference usually means narrow or corroded supply pipes to the upper floor.