If water pressure suddenly drops throughout the home, check your water provider’s outage or maintenance notices first.

Ask a nearby neighbor whether their supply has changed too. In an apartment or condominium, contact building management.

Watermain repairs and nearby maintenance can affect several properties at once. Toronto’s water department recommends checking construction notices and neighboring homes when investigating a sudden loss of supply or pressure.

If the utility confirms a supply problem, follow its instructions. There is little benefit in taking apart your faucets while the incoming supply is affected.

Follow any boil-water or water-quality notice separately. Restored pressure does not automatically mean an advisory has ended.

If only one sink has weak flow, inspect the aerator first.

The aerator is the small fitting at the end of many faucet spouts. Its screens can collect grit and mineral deposits.

To clean a removable aerator:

Some aerators unscrew by hand. Recessed versions may need a specific key, while other designs are not intended for routine removal. Moen’s maintenance guidance describes these different types and identifies accumulated debris as a cause of restricted flow.

If there is little improvement, continue with the local supply checks.

When the sinks work normally but the shower feels weak, inspect the showerhead.

Look for blocked spray holes, uneven spraying, and mineral deposits. On a handheld shower, check that the hose is not kinked or crushed.

For cleaning:

Delta recommends wiping deposits from its flexible Touch-Clean spray holes and a diluted vinegar solution for certain other showerheads. That guidance is product-specific: check compatibility before soaking a different model or finish.

Do not drill the openings or remove flow-control parts. Cleaning should restore the fixture’s intended performance.

If cleaning makes no difference, the restriction may be in the shower valve or its supply.

For a weak sink faucet, inspect the valves underneath it.

A valve may have been left partly closed after a repair. A flexible hose may also have become kinked when something was moved inside the cabinet.

Check for:

A quarter-turn valve is generally open when its handle lines up with the pipe. Multi-turn valves usually open counterclockwise, but follow the valve’s design and instructions.

Move accessible homeowner-operated valves gently. Do not force a seized valve or disturb a leaking one.

A damaged hose or faulty valve needs repair or replacement. Shut off the appropriate supply before disconnecting anything.

If several fixtures are affected, locate your home’s main shut-off valve.

It may be near the water meter, where the service pipe enters the building, or in a utility area. Its position varies by property and region.

Check whether it was left partly closed after recent work. Only operate a valve that you know is intended for homeowner use.

Do not operate utility-owned street valves, remove meter fittings, or interfere with sealed equipment.

If your valve is stiff, badly corroded, or leaking, have it assessed rather than forcing it open.

An apparently open handle also does not prove that an old valve is working correctly internally. If the basic checks do not resolve the problem, a plumber can test for a restriction.

If your home has a sediment filter, water softener, or other treatment equipment, check its maintenance record and operating instructions.

A loaded filter or equipment fault can restrict the water reaching downstream fixtures.

For a cartridge filter:

Never open a pressurized housing.

If the equipment has a manufacturer-approved bypass, it may help a technician isolate the restriction. Do not bypass treatment needed to make the water safe to drink unless the manufacturer or a qualified professional confirms an appropriate procedure.

Avoid changing unfamiliar valves simply to see what happens.

A significant leak can reduce the water available at your fixtures. It can also cause damage long before it becomes obvious.

Look for:

If you have an individual water meter, check for unexplained use:

Movement can indicate a leak or an overlooked automatic water user. Water Corporation recommends comparing meter readings while all water-consuming equipment is off.

A meter test does not locate the leak. If water continues moving and you cannot explain why, arrange an investigation.

For a visible leak under a sink, see our guide to fixing a leaking pipe under the sink.

A gauge helps distinguish low incoming pressure from restricted flow.

Use a suitable cold-water connection, such as a compatible outdoor hose tap. Make sure you know whether that tap is supplied before or after any regulator or treatment equipment.

To take a static reading:

The EPA recommends incoming household pressure of 45–60 psi, approximately 310–414 kPa, for efficient operation. This is guidance, rather than one universal required range for every home in the US, Canada, or Australia. Check your local requirements and equipment specifications.

A plumber can also compare pressure while water is flowing. A normal static reading followed by a substantial drop under demand can point toward a restriction or limited supply capacity.

A bucket-and-timer test measures flow, not pressure. It is useful for comparing a fixture before and after cleaning, but cannot replace a gauge test.

Some homes have a pressure-reducing valve, also called a pressure regulator, near the incoming supply.

Its purpose is to lower excessive incoming pressure. It cannot create pressure that the supply does not provide.

If earlier checks have not explained whole-house low pressure, have the regulator assessed alongside the incoming supply.

Do not turn its adjustment screw blindly. Adjustment should be based on measured pressure, the manufacturer’s procedure, local requirements, and the ratings of connected equipment.

Replacing or installing a regulator should be handled by a qualified plumber where required.

If cold water is normal but hot water is weak at several fixtures, concentrate on the hot-water system.

Possible restrictions include heater connections, mixing valves, or other components in that supply path. Arrange servicing rather than dismantling a heater or adjusting gas, electrical, or safety controls.

If both hot and cold flow have weakened gradually, older pipework may need assessment. Internal corrosion or deposits can restrict some pipes, but weak flow alone does not prove that the home needs repiping.

Private wells need a different investigation involving the pump, controls, pressure tank, and available water supply. Leave electrical work and pressure-system adjustments to an appropriate technician.

In freezing weather, a sudden loss of flow may also involve frozen pipework. Do not use a flame to thaw a pipe.