Visible indicators documented during inspection — galvanized steel supply piping, cast-iron main drains, corrosion, staining, slow drainage, leakage traces, mixed or patched plumbing — limitations of visual inspection regarding interior condition of concealed pipes and remaining service life, and the need for evaluation by a licensed plumber or camera inspection. Educational page — not a service-life guarantee, not a confirmation of hidden leaks, not legal advice.
Galvanized steel plumbing was commonly used for water supply piping in homes built before 1970. Its nominal service life is generally 40-60 years, but it is subject to internal corrosion (which progressively reduces useful diameter, flow, and water quality) — a phenomenon often invisible from the outside. Cast-iron main drains were widely used for vertical stacks for wastewater drainage until the 1980s. Their nominal service life is longer (50-100 years), but they are subject to internal corrosion, flaking, and localized perforations — particularly at joints and horizontal sections. During a visual inspection, we document visible indicators in accessible areas (basement, crawlspace, mechanical room) and risk conditions. Much of the plumbing is concealed behind walls, in floors, or in soffits — therefore inaccessible to visual inspection.
Here are the visible indicators we systematically document when older plumbing is suspected or observed in accessible areas. These indicators guide toward evaluation by a licensed plumber — they confirm neither imminent failure nor remaining service life.
Galvanized steel supply piping in accessible areas (basement, crawlspace, mechanical room, behind water heaters): grey or silver colour, characteristic rough texture, threaded connectors, often rusted around connection points. Typical presence in pre-1970 homes.
Vertical stacks and accessible sections of main and secondary cast-iron drains: black or dark grey colour sometimes covered with patina or rust, large diameter (3-4 inches or more), original mortar joints or metal band clamps on replacement sections.
Surface rust stains, flakes or detached plates, mineral crusts at connections, apparent perforations, weeping through joints. Indicators of exterior deterioration that may reflect (but does not confirm) interior deterioration.
Slow evacuation at sinks, bathtubs, showers, or the basement floor drain. May indicate internal diameter reduction from scale buildup, corrosion, or partial blockage. Precise diagnosis through camera inspection (separate service).
Water rings on basement ceiling under bathrooms or kitchen, wet stains at the base of vertical stacks, mineral salt deposits (efflorescence) on metal pipes, stained or warped finishes. Priority indicators of active or past leakage warranting prompt verification.
Connections between different materials: galvanized + copper, copper + plastic ABS or PEX, cast iron + ABS. Visible partial repairs at joints. Indicator of prior interventions whose quality and durability depend on workmanship — to be validated by a licensed plumber.
Important: these visible indicators document conditions observed at the time of inspection. A visual inspection does not confirm the interior condition of pipes, does not measure residual thickness, does not guarantee remaining service life, and does not diagnose leaks concealed behind finishes. Not all galvanized or cast-iron plumbing needs to be replaced — evaluation by a licensed plumber determines the actual condition and appropriate actions. Drain camera inspection is a separate service that is not included in a standard pre-purchase inspection. We do not provide plumbing repair instructions or legal advice.
Our visual inspection follows the InterNACHI standard. For plumbing, limitations are important — much of the system is concealed and its interior condition cannot be confirmed by visual observation.
Our report documents visible indicators and risk conditions, and recommends, on a case-by-case basis, intervention by a licensed plumber and/or drain camera inspection based on the nature of observations.
Galvanized plumbing and cast-iron drains are concentrated in pre-1970 housing stock. Evaluation remains case-by-case based on actual age, renovation history, and observed conditions.
Regions with predominantly more recent construction (Laurentians cottages post-1990, Lanaudière post-2000) are less affected by these materials, but any pre-1970 home in these regions merits case-by-case evaluation.
If the pre-purchase inspection reveals visible galvanized plumbing or cast-iron drains and the condition-removal deadline is short, several options are available depending on your risk tolerance and the seller's cooperation.
What is documented during an inspection, what is not, and when to consult a licensed plumber or request a camera inspection.
Pre-purchase inspection in Greater Montreal. Report within 24h*. InterNACHI Certified · IBC Network. Thousands of inspections.