A weak shower. A kitchen faucet that takes forever to fill a pot. A toilet that refills slowly after every flush. Low water pressure is one of those problems that’s easy to dismiss as a minor inconvenience — until it isn’t.

In Mission and across the Fraser Valley, water pressure issues are more common than most homeowners realize, and they rarely fix themselves. The cause could be as simple as a partially closed valve or as serious as a corroding main supply line. In some cases, it can even be related to sediment buildup in your water heater. Knowing the difference saves time, money, and frustration. Delaying a diagnosis can lead to hidden costs from water damage and inefficient appliances.

What Counts as Low Water Pressure?

Normal residential water pressure in BC runs between 40 and 80 PSI (pounds per square inch). Below 40 PSI and most homeowners start to notice — showers feel weak, appliances like dishwashers and washing machines run inefficiently, and filling a bathtub tests your patience.

If you want to know your actual pressure, a simple pressure gauge screwed onto a hose bib will give you a reading in seconds. They’re available at any hardware store for under $20 and are worth having on hand.

Is the Problem Throughout the House or Just One Fixture?

Before calling a plumber, it’s worth narrowing down where the problem is happening.

If pressure is low at every fixture throughout the home, the issue is upstream — either at the municipal supply, the pressure reducing valve, the main shut-off, or the main supply line.

If pressure is low only at one fixture — a single faucet or showerhead — the problem is usually local: a clogged aerator, a failing cartridge, or a partially closed fixture shut-off valve.

That distinction tells you a lot before anyone opens a wall.

Common Causes in Mission Homes

Clogged Aerators and Showerheads

The simplest and most common cause of low pressure at a single fixture is mineral buildup. Mission’s water supply contains calcium and magnesium, and those minerals gradually clog the small screens and openings in faucet aerators and showerheads. Unscrewing the aerator and soaking it in white vinegar overnight often restores full flow immediately. If that doesn’t fix it, the cartridge inside the faucet may be the culprit.

Pressure Reducing Valve (PRV) Failure

Most homes built after the 1980s have a pressure reducing valve — a bell-shaped device typically installed near where the main water line enters the home. Its job is to bring municipal supply pressure (which can exceed 100 PSI) down to a safe residential range. PRVs typically last 10 to 15 years. When they fail, they can either allow pressure to spike dangerously high or drop it to uncomfortably low levels.

If your pressure has dropped noticeably and your home has a PRV, testing and replacing it is one of the first things Watson Ink Plumbing checks. It’s a straightforward repair that can restore normal pressure the same day.

Partially Closed Shut-Off Valves

It sounds obvious, but this is more common than you’d think. After any plumbing work — a repair, a water heater replacement, or even a home inspection — a shut-off valve sometimes doesn’t get opened all the way back up. The main shut-off valve is typically in the basement, utility room, or crawl space. Make sure it’s fully open (turned counter-clockwise as far as it goes for a gate valve, or handle parallel to the pipe for a ball valve).

Corroded or Narrowed Pipes

Mission has a significant number of homes with original galvanized steel supply pipes. Galvanized pipe corrodes from the inside out, and that corrosion accumulates over decades — narrowing the inner diameter and dramatically reducing flow. A galvanized pipe that was originally 3/4 inch in diameter might have an effective interior opening of a quarter inch after 40 years of corrosion. If your home has galvanized plumbing and low pressure, the pipe itself is the problem. The long-term fix is replacing the supply lines with copper or PEX.

Leaks in the Supply Line

A significant leak in the main supply line — whether inside the home or underground between the meter and the house — will reduce pressure at every fixture. Signs include an unusually high water bill, wet spots in the yard between the meter and the foundation, or water stains in the basement or crawl space. If your meter is running when everything in the house is off, you have a leak somewhere.

Municipal Supply Issues

Occasionally, low pressure is not your problem to solve — it’s the municipality’s. If your neighbours are also experiencing low pressure at the same time, or if it coincides with nearby construction or a water main break, the issue is in the City of Mission’s distribution system. You can report it to the City directly and check for any active notices on their website.

What a Plumber Can Do

Watson Ink Plumbing carries a full diagnostic process for pressure issues — from testing at the main supply through to individual fixture assessment. For homes with galvanized pipe, we can advise on repipe options that restore full pressure and improve water quality at the same time. PRV replacement, shut-off valve upgrades, and supply line repairs are all standard work our Mission team handles regularly.

If your water pressure isn’t what it used to be, get in touch and we’ll find out why. Low pressure is fixable — it just needs a proper diagnosis first.