Water service line and galvanized pipe replacement

Galvanized pipe installed in Montreal homes up to the 1950s doesn't rust from the outside — it closes up from the inside. A 3/4-inch pipe installed in 1935 can narrow to pencil width after decades of rust buildup. Pressure drops, hot water beats cold to the tap because cold has to fight its way through, and a modern dishwasher struggles to fill.

Replacement runs in copper or PEX, from the service box to the risers. On the portion of the water service that belongs to the municipal network — often lead in areas built before 1970 — coordination with the borough's public works department is needed before the water gets shut off.

On a duplex or triplex, the private portion can usually be redone in a day, shutoff included. We confirm whether the line is lead or galvanized before quoting, and never touch only the private portion when the public portion is also part of an active municipal replacement effort.

On site, the three materials can usually be told apart without opening the whole wall. Galvanized is dull grey, threaded at every joint, and a magnet sticks to it — it's zinc-coated steel, not stainless. Copper stays reddish or greenish depending on oxidation and never pulls a magnet. Lead is dull and almost waxy to the touch, and a light knife scratch leaves a shiny mark without flaking the metal, where steel and copper resist that scratch. The distinction matters because lead gets a different priority: even a short lead section feeding a single fixture is worth flagging and replacing, while a galvanized section elsewhere on the same run that's still in decent shape can wait.

A spot fix — a repair clamp over a localized leak — never restores the flow lost to interior corrosion on the rest of the run; it stops the leak, not the pressure drop. Full replacement becomes the only real option once the pressure loss shows up at several taps rather than one specific point. We also avoid tying new copper straight onto existing galvanized without a dielectric union: contact between the two metals speeds up galvanic corrosion, and the next problem shows up sooner than it should.

Price mostly comes down to the run length between the curb stop and the service box, and the frost line depth — roughly 1.2 to 1.5 metres in Montreal — which sets the minimum trench depth. A line that crosses a driveway or sidewalk means saw-cutting concrete and sometimes a street-occupation permit, both of which add to the job. A finished basement also complicates interior access to the service box, where an unfinished one lets us open the floor directly. For the private portion alone, the range runs about $3,500 to $7,000 depending on these factors.

Building age is the first clue before anyone opens a wall. In the brick duplexes built before 1920 north of Sherbrooke Street in NDG, the original water service is more often lead, sometimes tied into galvanized further in. In the stretch built through the 1920s to 1940s near Somerled Avenue, lead is less common and galvanized dominates almost everywhere — a replacement there usually touches one material instead of two.

Replacement usually goes by open trench, from the sidewalk to the house, because few of these original services sit inside a sleeve that would allow a trenchless method. Winter complicates the job: digging in frozen ground needs extra equipment and stretches out the timeline, which is why most homeowners plan the replacement between snowmelt and the next freeze rather than in the middle of January.