Galvanized Pipe Replacement in Ontario: What to Know Before You Replumb

What is galvanized pipe?

Galvanized steel pipe is steel pipe coated with a layer of zinc. The zinc coating was intended to prevent rust by acting as a sacrificial barrier — corroding in place of the underlying steel. This approach was effective initially, and galvanized pipe was the standard for residential water supply in Ontario from the early twentieth century through the late 1950s, when copper became widely available and began to replace it.

If your home was built before 1960 and has not had its supply piping updated, there is a high likelihood that at least some of the supply piping is galvanized steel. In the Greater Toronto Area, this encompasses tens of thousands of homes — particularly in established neighbourhoods like East York, Etobicoke, Hamilton's North End, and older inner-ring suburbs across the GTA.

Why galvanized pipe fails

The failure mode of galvanized pipe is internal: the zinc coating breaks down over 30 to 50 years, and without that protective barrier, the underlying steel begins to corrode. Rust and mineral scale accumulate on the interior walls of the pipe — a process called scaling. Unlike a corroding exterior, interior scaling is invisible from the outside.

As scale accumulates, the effective interior diameter of the pipe shrinks. A pipe that started with a 3/4-inch interior might eventually have an effective opening of 1/4 inch or less in heavily scaled sections. This progressively reduces water flow and pressure throughout the system — not just at one fixture, but everywhere.

Eventually, the pipe body or threaded joints begin to fail — first as small leaks that can worsen quickly. In advanced cases, a fitting can fail entirely. Galvanized pipe at its end of service life may look perfectly intact on the outside while being severely compromised internally.

Signs of galvanized pipe problems

• Low water pressure at multiple fixtures — particularly if it was not always this low and has worsened over years
• Rust-coloured or brown water — especially the first water drawn in the morning after the pipes have been still overnight
• Visible rust at fittings or joints — surface corrosion at threaded connections or where pipe passes through walls
• Frequent small leaks at fittings — threaded galvanized joints are common failure points as corrosion thins the pipe walls
• Water discolouration affecting appliances — brown staining in toilet tanks, bathtubs, or on white laundry indicates rust in the supply
• Uneven pressure between floors — in two-storey homes, the upper floor often suffers greater pressure loss because scale is worse in horizontal pipe runs

Risk level by age

Galvanized pipe lifespan varies with water quality, pressure, and installation quality, but age is the most reliable risk indicator:

• Under 40 years: Low risk; monitor but no action typically needed
• 40–60 years: Moderate risk; worth having assessed, particularly if pressure has declined or water is discoloured
• 60–70 years: High risk; should be assessed; replacement likely warranted
• Over 70 years: Very high risk; near or past end of service life; plan replacement; do not wait for a leak

In practical terms, Ontario homes built before 1960 with original plumbing are now at the 65+ year mark and should be assessed by a licensed plumber, regardless of visible symptoms.

Replacement options

Whole-home repipe

A whole-home repipe replaces all supply piping from the main shutoff to each fixture throughout the home. This is the comprehensive solution — it eliminates galvanized pipe entirely and restores full flow and pressure to all fixtures. It is a significant project, but it is often the most cost-effective choice when galvanized pipe is pervasive, when multiple sections are failing, or when a major renovation is already underway and walls are open.

Selective replacement

Selective replacement targets the most affected sections — typically the horizontal runs in the basement or the sections serving the fixtures with the lowest pressure. This is a reasonable approach when only part of the system is failing, or when budget constraints require a phased approach. A plumber can assess which sections are most critical and sequence replacement accordingly.

PEX vs. copper: which material for your repipe?

Both copper and PEX (cross-linked polyethylene) are excellent, Ontario Plumbing Code-compliant supply pipe materials. The choice between them involves trade-offs:

Many licensed plumbers offer both options. For most whole-home repipes in Ontario today, PEX is the common choice — faster installation means less disruption and lower overall cost. Copper remains the choice where aesthetics matter (exposed piping) or where specific compatibility is needed.

Ontario permit requirements

In virtually all Ontario municipalities, supply pipe replacement — whether a full repipe or selective replacement — requires a plumbing permit. The permit process involves submitting work plans, the municipality issuing a permit, a licensed plumber doing the work, and a municipal plumbing inspector reviewing the completed work before walls are closed.

A licensed plumber handles the permit application as part of the project. Do not engage a contractor who proposes doing this work without a permit — unpermitted plumbing work can create problems at resale, with insurance claims, and with home warranty coverage.

What to expect during a repipe

A whole-home repipe is a significant but manageable project when done by an experienced plumbing team. Here is what the process typically looks like:

• Assessment and planning: A licensed plumber reviews the home's layout, identifies the routing of existing supply pipe, and plans the new pipe routing. This determines which walls and ceilings will need to be accessed.
• Permit application: The plumber applies for the required plumbing permit with the municipality before work begins.
• Main shutoff and drain-down: Water is shut off at the main and the system is drained before any pipe is cut.
• New pipe installation: New supply piping is run through the home. The goal is to minimize wall openings — an experienced plumber works strategically, often routing through the basement and up through closets and utility spaces.
• Connection to fixtures: New supply lines are connected to each fixture — sinks, toilets, showers, appliances, hose bibs, and the water heater.
• Pressure test and inspection: The new system is pressure tested before walls are closed. The municipality's plumbing inspector reviews the work.
• Wall patching: Drywall openings are patched. This may be done by the plumbing contractor or arranged separately.