Pipe corrosion is one of the most common and costly plumbing problems homeowners face. It usually develops slowly and out of sight, inside walls and under floors, until it shows up as a pinhole leak, discoloured water, or a damp ceiling. Left unchecked, badly corroded pipes can require a total replacement of your pipes.
The good news: understanding what causes corrosion makes it much easier to slow it down, catch it early, and protect your home.
Which Pipes Corrode?
- Galvanized steel, common in homes built before the 1960s, is the most corrosion-prone. It rusts from the inside out, restricting flow and eventually leaking.
- Copper is durable but can develop pinhole leaks over time, especially with aggressive water chemistry or high water velocity.
- Cast iron drain pipes in older homes can corrode and crack after decades of use.
- Plastic pipes like PEX and PVC don’t corrode. Older Poly-B plastic pipe doesn’t rust, but it can degrade and become brittle over time, which is why many insurers ask homeowners to replace it.
For a closer look at each material, see our guide to the common types of plumbing pipes.
What Causes Pipe Corrosion
- Water chemistry. Water that is too acidic (low pH) slowly eats away at metal pipes, while very hard water leaves mineral scale that can trap corrosion underneath it.
- Dissimilar metals. When copper is connected directly to galvanized steel, an electrochemical reaction called galvanic corrosion causes the joint to deteriorate quickly.
- High water pressure and velocity. Fast-moving water, especially at elbows and fittings, gradually wears away the inside of copper pipes.
- Age. Every metal pipe system wears out eventually. Pipes installed 40 to 60 or more years ago are far more likely to be corroded.
Warning Signs of Corroded Pipes
- Brown, red, or yellow tinted water, especially when you first turn on a tap
- A metallic taste or smell in your water
- Dropping water pressure throughout the house
- Green or blue stains on copper fittings, or rust and flaking on visible pipes
- Small, recurring leaks, water stains, or an unexplained jump in your water bill
How to Minimize Pipe Corrosion
Check Your Water Quality
Calgary’s tap water is treated by the city, so you don’t need to add chlorine or other chemicals yourself. Doing so can actually harm your pipes. Calgary water is moderately hard, though, so scale is a common issue. A water softener or filtration system reduces mineral buildup and protects pipes, fixtures, and appliances. If you’re on a private well, have your water’s pH tested.
Keep Water Pressure in a Safe Range
Household water pressure is typically best between about 40 and 80 psi. Pressure that runs too high strains and wears your pipes. A plumber can test your pressure and install or adjust a pressure-reducing valve if needed.
Use the Right Fittings Between Different Metals
Where copper and steel pipes meet, a dielectric union or fitting separates the metals and prevents galvanic corrosion. If your home has mixed pipe materials, ask a plumber to check those connections.
Replace Galvanized Pipe
Galvanized steel can’t be protected long-term. Once it starts corroding, the damage continues from the inside. Replacing it with modern PEX or copper is the lasting solution.
Schedule Regular Inspections
A professional plumbing inspection every few years, or whenever you notice warning signs, catches corrosion before it turns into a leak. Hidden leaks can be found without opening walls through professional water leak detection.
Repair or Repipe?
A single corroded section can often be repaired. But if leaks keep appearing in different spots, water is discoloured throughout the house, or your home still has galvanized or Poly-B piping, repiping is usually more cost-effective than repeated repairs. For leaks happening now, our team provides fast pipe leak repair.
Get Your Pipes Checked
ProStar Plumbing & Heating has helped Calgary homeowners protect their plumbing since 1996. If you’ve noticed discoloured water, low pressure, or recurring leaks, call us at (403) 250-7232 or contact us online to book an inspection.