From the Archive: Old Steel
Galvanized Pipes in Older Homes
Grey steel pipes with threaded joints were standard in houses built before the 1960s. Decades later, many are rusting from the inside out.
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What you need to know
Galvanized steel supply pipe was coated with zinc to slow rust. Over many decades the zinc erodes away and the steel corrodes inside, narrowing the pipe. The result is low pressure, discoloured water and eventually leaks, usually at the threaded joints.
Checking your own pipes
- Find exposed piping in the basement near the water heater or primary shut-off.
- Look at the colour. Galvanized is dull grey or silver; copper is orange-brown; plastic is white, grey, blue or red.
- Try a magnet. It sticks firmly to galvanized steel and not to copper or lead.
- Look at the joints. Galvanized line is joined with threaded fittings rather than soldered or crimped joints.
- Run a cold tap after the water sits overnight. Brown or rusty water at first is a sign of internal rust.
Many older homes have a mix: copper added in renovations and original galvanized hidden in walls. A partial check may miss sections.
Keep this kit by the main shut-off
- Flashlight or headlamp
- Bucket and old towels
- Adjustable wrench and slip-joint pliers
- Flange plunger for toilets, cup plunger for sinks
- Label on the main valve so anyone can find it
What not to do
- Do not join copper directly to galvanized without a proper dielectric fitting; the two metals corrode each other.
- Do not overtighten old threaded joints. Corroded pipe can snap.
- Do not assume a single leak repair has solved the problem.
Stop and phone a plumber when
- 1A ceiling or wall starts dripping
- 2More than one drain backs up at once
- 3You smell gas or sewage indoors
- 4A valve will not turn or drips when touched
When to get a plumber
If pressure is poor at several fixtures, water is discoloured or you have had more than one leak, it is time to plan replacement. Our whole-home repiping page explains the process, and service line replacement covers the pipe from the street. Also read low water pressure causes and lead service lines.
Straight answers to common calls
Is galvanized pipe dangerous to drink from?
The main issues are rust and reduced flow. Older pipes can also collect lead from upstream sources, so testing is wise in very old homes.
Can I replace galvanized in stages?
Yes, though doing it all at once is usually more efficient.
Keep reading
- Whole-Home Repiping in Oakville
Patch after patch, leak after leak.
- Common Causes of Low Water Pressure
A shower that dribbles, a hose that barely reaches the garden.
- Lead Water Service Lines: What to Know
Most Oakville homes never had a lead pipe.
- Water Service Line Replacement in Oakville
One pipe carries every drop into the house, from the curb stop to the meter.
Ready when you are
One call books the visit. Tell us what you are seeing and we will tell you straight what it likely is.