Primer ยท Water Supply
Why Your Water Pressure Is Low
A shower that dribbles, a washing machine that takes forever to fill. Low pressure has a short list of causes, and you can rule out several yourself.
- Plain steps you can do yourself, safely
- Clear signs for when to stop and call
- Written for Newmarket houses and water
- A plumber on the phone if it goes sideways
What goes wrong in the pipes
Weak pressure is annoying, but it can also be a clue. It might be a clogged aerator that takes two minutes to fix. It might be a hidden leak wasting water, a failing pressure-reducing valve, or old pipe closing up from the inside. Figuring out which one you have saves money and, in some cases, prevents damage.
The first thing to learn is the pattern. Is it one fixture, one floor, hot water only, or the whole house? Each answer points somewhere different.
Have these on hand
- Flashlight
- Adjustable wrench
- Towels and a bucket
- Our number on the panel door
Hands-on steps
- Check one fixture first. Unscrew the aerator on a weak faucet and look for grit or scale. Clean or replace it and test again.
- Compare hot and cold. Weak flow on the hot side alone, the problem may be at the water heater: a partly closed valve, sediment, or a failing dip tube.
- Check the main valve. Make sure the main shut-off is fully open. After plumbing work, it is sometimes left partway closed.
- Find the pressure-reducing valve. Many homes have one near the main shut-off. A failing valve can drop pressure throughout the house.
- Look for leaks. Turn everything off and watch the water meter. If it keeps moving, water is going somewhere it should not.
- Ask the neighbours. If they have the same problem, it may be a municipal issue, such as main repairs or a hydrant flush. The town can confirm.
Mistakes that turn a small repair big
- Turning up a pressure-reducing valve too far. High pressure strains fixtures, hoses and appliances. Most homes do best in a moderate range.
- Replacing fixtures before checking the supply. A new shower head will not help if the pipe feeding it is choked.
- Ignoring a sudden drop. Pressure that falls quickly can mean a leak or a failure upstream.
- Assuming it is always the town. Municipal pressure problems usually affect a whole street, not just one house.
When to put the tools down and call
Call when the problem affects the whole house and you have checked the main valve, when only hot water is weak, or when you suspect a leak. Older homes with galvanized steel pipes often lose pressure as rust narrows the pipes over decades, and the fix is usually replacing those sections.
If your water heater is a rental and the hot side is the weak one, a rental water heater swap may solve it along with a few other headaches. While we are looking at the main line, raise the idea of a backwater valve for that basement. The two systems sit close together in many homes, and checking both in one visit saves a second trip.
Asked on site
What is normal water pressure for a house?
Many homes run somewhere around 50 to 70 psi. A plumber can test your actual pressure with a gauge on a hose bib or laundry tap.
Why is my water pressure low in only one bathroom?
Usually it is the fixtures in that room: clogged aerators, a blocked shower head or a partly closed shut-off valve. Old pipe feeding that bathroom can also be the cause.