The Most Common Causes for Water Pressure Loss

Most homeowners don’t think about their home’s water pressure until the pressure drops and they notice a problem. Strong shower streams, efficient appliance performance, and reliable fixtures all depend on optimal home water pressure. When your home water pressure drops, the culprit is often the plumbing system.

Our Victoria plumbers have decades of experience diagnosing and resolving home water pressure issues. Within this latest guide, we’ll explain the most common causes for pressure loss and the steps you can take to restore the ideal pressure to your home plumbing equipment.

Partially Closed or Restrictive Valves

One of the simplest plumbing causes of low pressure is a valve that’s not fully open or a valve that’s too small for the flow demands. Your main shut-off valve (where the water supply enters your home) or a meter valve may have been left partially closed after recent service, repair, or renovation work. If these valves sit in a position that restricts flow, you’ll experience lower water pressure throughout the entire home.

If your home has a pressure-regulating or pressure-reducing valve, it could be set too low or malfunctioning, which can limit property-wide water pressure levels.

The steps to take in identifying and resolving water pressure issues caused by restrictive valves:

• Locate and fully open the main shut-off valve and the meter valve (if accessible).

• If there’s a PRV, check its setting; if pressure is lower than the PRV setting, it might be failing.

• Call your plumber for a plumbing inspection to check if the valve is undersized for the flow.

Blockages, Mineral Build-Up, and Clogged Pipes

Over time, sediment, sand, rust flakes, or mineral deposits can restrict pipes.

When debris reduces the inner diameter of a pipe, water flow and effective pressure at the fixture drop. The blockage restricts the flow rate, even if the overall system pressure levels are normal, causing weaker flow throughout the property.

Galvanized or steel pipes in older homes often accumulate rust or scale internally, which eventually causes blockages. Debris can also accumulate at the elbow joints after a series of micro-clogs.

The steps to take when a clogged pipe causes low pressure:

• Clean or replace screens/filters in the supply line (including softeners or whole-house filters).

• In older homes with galvanized piping, call Thunderbird Plumbing to evaluate the feasibility of repiping services.

Corroded or Deteriorated Pipes

Corrosion reduces a pipe’s internal diameter and can lead to leaks, which lower water pressure. Galvanized steel pipes typically begin to corrode within 20 years, while copper or brass have longer life-spans but require careful professional inspections.

Corrosion along the pipe interior can cause turbulence and pressure drop, especially at fitting bends or when branching to smaller pipes. If multiple fixtures rely on undersized or corroded branch lines, the cumulative effect may be a noticeable drop in performance.

The steps to take in evaluating pipe corrosion or deterioration:

• Identify the age of your pipes and their material.

• Book a pipe inspection to check for visible piping for signs of rust, pitting, or “chalky” scale.

• Schedule a repiping quote to address future corrosion concerns.

Leaks Within the Plumbing System

Leaks don’t just waste water. They also reduce the volume of water available to your fixtures, thus reducing effective pressure. Even relatively small leaks (hidden behind walls, under slabs, or in crawl spaces) can cause severe water pressure loss.

If water is leaking before reaching the taps or shower, there’s a limited supply and lower flow. Look for signs such as damp spots, soil saturation in crawl spaces, hissing sounds, or meter movement when all faucets are off.

The steps to take if you believe you have a water leak:

• Stop all home water usage and observe the water meter: if it continues to turn, a leak is likely.

• Inspect for visible moisture, drips, or dampness near fixtures, pipes, or under the house.

• When you suspect a hidden leak in the home(for example, under a slab) call a licensed plumber for leak-detection and repair.

Undersized or Improperly Sized Pipework

If you’ve made recent upgrades to your home that altered the plumbing (for example, installing a new bathroom or upgrading laundry rooms), your pipes may not meet the new demand. Branches could be too narrow, and you may face limited water pressure when multiple fixtures operate simultaneously.

Small-diameter pipes increase friction losses and reduce pressure delivered to the far ends of the system. This is a common plumbing issue in homes with multiple bathrooms or in older buildings.

The steps to take if you suspect your water pressure issues relate to undersized pipes:

• Map your plumbing system: note pipe sizes, lengths, and number of fixtures per branch line.

• If long runs of ½″ pipe serve multiple fixtures, consider upgrading branch lines to ¾″ or larger where feasible.

• Consider hiring a plumber for a retrofit if you’re unsure whether recent plumbing work adheres to sizing codes.

Fixture-Specific Pressure Loss Issues

Not all water pressure issues affect the whole home. If the problem is localized to one faucet, one shower, or one floor, the culprit may be a simple fixture issue.

Aerators (the screens on faucet outlets) and shower head nozzles get clogged with mineral deposits, debris, or rust. This can restrict flow without reducing actual supply pressure, but the loss of pressure effect is the same.

Likewise, mixing valves and cartridges inside taps/shower valves may clog or wear down and restrict hot-water flow more than cold, giving the impression of “low pressure on the hot side only”.

The steps to take if you suspect fixture-specific water pressure loss:

• Remove and clean aerators or showerheads. Soak them in vinegar to remove the mineral scale.

• Test other fixtures to isolate areas of pressure loss.

• Call Thunderbird Plumbing to replace old or malfunctioning faucet cartridges or shower mixing valves.

External Supply or Shared Line Factors

Supply issues outside your home may also be the culprit behind water pressure loss. Maintenance on a nearby municipal water line or local leaks may cause intermittent pressure issues. If you share a line with neighbours and they increase water use, you may experience a loss of pressure to your property as a result.

The steps to take if you suspect external factors are causing pressure loss:

• Ask neighbours if they’re experiencing similar water pressure issues.
• Contact your water supplier to determine if pressure reductions or work are underway.
• Book a visit from Thunderbird Plumbing to assess the shared supply and identify potential options for restoring pressure.

Thunderbird Plumbing is Your Victoria Expert for Water Pressure Analysis and Plumbing Repair

When you experience low water pressure and require experienced guidance to analyze the cause and restore the flow to your home, depend on Thunderbird Plumbing.

Our Victoria plumbers have decades of experience serving communities throughout Greater Victoria, including Colwood, Saanich, Oak Bay, and Langford. We offer a 5-star service, backed by hundreds of local reviews and an exceptional industry reputation.

To speak with a plumber, call our dispatch team at 778-402-9431 or schedule your low water pressure analysis online!

Answers to Your Low Water Pressure Questions

How can I determine if the low pressure affects one fixture or the entire house?

Shut off or isolate other water-using appliances and test one faucet. If only one fixture shows low flow, it’s probably a fixture-specific issue (aerator, cartridge, clogged supply). If multiple fixtures show low flow, it’s likely a system-wide issue. 

What’s a normal water pressure reading in a home?

For most homes, pressure levels of between 40 and 80 psi are considered normal, with around 50-60 psi being comfortable for most fixtures. Readings significantly below that can cause a performance drop.

Can I fix low pressure myself, or do I need a plumber?

Some fixes are DIY-friendly: check and open valves, clean aerators, and remove filter screens. But issues like internal pipe corrosion, hidden leaks, improper pipe sizing, or failing PRVs are best handled by licensed plumbers.

When should I consider installing a booster pump?

If your home consistently receives low pressure due to elevation, a long service line, or a shared supply, and internal plumbing is functioning well, then a booster pump may improve pressure. This is a more advanced solution that requires professional installation and pressure regulation to prevent damage to fixtures.

Could a pressure regulator be the culprit?

A malfunctioning PRV (pressure regulator valve) may set your pressure too low or fail entirely, limiting your home’s supply even though the municipal source is fine. Testing with a pressure gauge can help you isolate any regulator issues.

What’s the best first step when I notice low pressure?

Start with the simplest checks: ensure the main valves are fully open. Inspect and clean aerators. Ask neighbours if they see the same issue. If the problem persists, measure your system pressure and then investigate deeper plumbing causes, such as leaks, corrosion, and pipe sizing.