Plumbing problems are among the most common findings in a home inspection, and some of the most costly if missed. The biggest red flags are pipe materials with a history of failure, active or past leaks, an old or poorly installed water heater, slow or backing-up drains, and signs of trouble in the sewer line. Most can be confirmed and priced by a licensed plumber before you commit.
Pipe materials to watch for
The type of supply and drain piping tells you a lot about what to expect. Some materials are known to cause problems as they age.
| Material | Where you may see it | Why it is a flag |
|---|---|---|
| Polybutylene (grey plastic supply pipe) | Homes built roughly from the late 1970s to the 1990s | Known for failures at fittings and pipe breakdown; many insurers ask about it |
| Galvanized steel supply pipe | Older homes | Corrodes from the inside, reducing flow and eventually leaking |
| Lead service lines or lead pipe | Older homes and neighbourhoods | Can add lead to drinking water; many cities have replacement programs |
| Cast iron drains | Older homes | Durable, but can crack or corrode with age |
| Clay or older sewer lines | Older homes | Prone to root intrusion, cracking and shifting |
Copper, PEX and modern plastic drain pipe are generally reliable when properly installed, though installation quality still matters.
Red flags during the inspection
Leaks and water damage
- Stains on ceilings below bathrooms and kitchens.
- Soft or stained flooring around toilets, tubs and showers.
- Corrosion, green or white deposits on fittings and valves.
- Drips or moisture under sinks and behind appliances.
- Musty smells or mould in cabinets or basements. See moisture, mould and indoor air.
Water pressure and flow
- Low pressure when two fixtures run at once, which may point to corroded supply pipes.
- Very high pressure, which strains fixtures and connectors; a pressure-reducing valve may be needed.
- Discoloured water when taps are first opened.
Drains and venting
- Slow drains in several fixtures, which can point to a problem in the main line rather than a single clog.
- Gurgling sounds or sewer smells, which can mean poor venting or dry traps.
- Missing or improper traps, such as S-traps under sinks.
- Signs of past backups at floor drains.
Water heater
- Age near or past the typical service life for its type; the manufacture date is usually on the label.
- Rust or water at the base of the tank.
- A temperature and pressure relief valve without a proper discharge pipe extending toward the floor.
- Venting problems on gas units, such as poorly sloped or disconnected vent pipes, or scorch marks near the burner.
- No seismic strapping where it is required, such as in parts of BC.
Gas smells and venting problems are urgent. If you smell gas, leave the building and call your gas utility from outside. Signs of spillage at a gas water heater or furnace vent should be checked by a licensed gas fitter before the appliance is used.
The sewer line
The main sewer line from the house to the city connection is out of sight but can be one of the most expensive repairs. In older homes, homes with large trees nearby, or homes with a history of backups, consider a camera inspection of the sewer line by a plumber. It can show roots, cracks, sags (bellies) and offset joints. A backwater valve helps protect against sewer backups; check whether one is present and working. See why basements leak for more on backups.
What to do with the findings
- Ask the inspector which findings are urgent, which need further evaluation and which are routine maintenance.
- Have a licensed plumber evaluate significant items and provide a quote before your conditions expire.
- Check with your insurer about any pipe materials that may affect coverage.
- Find out whether your municipality has programs for lead service line replacement or backwater valve installation.
Our guide on how to read a home inspection report helps sort findings into what matters now and what can wait.
How ehZee can help
An ehZee home inspection looks at visible supply and drain piping, fixtures, the water heater and signs of leaks. You can walk through with the inspector, ask questions on the spot and hear the findings on the day, with a written report within two days.
Common questions
Does a home inspection include a sewer camera inspection?
Usually not. A standard inspection covers visible plumbing. A sewer camera inspection is a separate service, typically done by a plumber or drain specialist.
Is polybutylene piping a deal-breaker?
Not necessarily, but it is worth pricing replacement and checking with your insurer before you buy.