Pinhole Leaks in Copper Pipe and the Water That Causes Them
Most of North America worries about hard water. The Lower Mainland has the opposite problem, and it shows up as tiny holes in otherwise healthy copper.
A pinhole leak is exactly what it sounds like: a hole barely wider than a needle, punched through a copper wall from the inside out by pitting corrosion. The pipe around it can look perfect. That is what makes these leaks expensive. A pinhole above a finished ceiling can run for weeks as a fine mist before anyone notices a stain, and by then the drywall, insulation and sometimes the framing have all been wet for a long time.
When WaterLine Plumbing's Surrey team finds one pinhole in a home, the first question is never whether to patch it. It is why the pipe corroded, because the answer usually applies to every other length of copper in the building.
Our Water Is Unusually Soft, and That Matters
Metro Vancouver's drinking water comes from three protected mountain watersheds: Capilano, Seymour and Coquitlam. Rain and snowmelt off granite picks up very little dissolved mineral on the way down, so what arrives at your tap has almost no calcium or magnesium in it. Regional water sits around 0.3 grains per gallon of hardness, roughly 5 mg/L expressed as calcium carbonate, which puts it among the softest municipal supplies on the continent.
That is excellent for kettles, glassware and soap. It is harder on copper. In a hard-water city, dissolved minerals precipitate out and lay down a thin scale layer on the inside of the pipe. That layer is a nuisance in fixtures and water heaters, but inside a copper line it acts as a barrier between the water and the metal. Very soft water never builds that barrier, so the copper stays chemically exposed for its entire service life.
Softness also means low alkalinity, which is the water's ability to resist a change in pH. With little buffering capacity, small shifts have an outsized effect on how aggressive the water is toward metal. Metro Vancouver runs a long-standing corrosion control program for exactly this reason, raising the pH of the regional supply and increasing alkalinity with natural minerals to make the water less corrosive to copper pipe, fixtures and hot water tanks.
This is not an argument for a water softener. Softeners remove hardness minerals, and the water here has essentially none to remove. Installing one in a Lower Mainland home addresses a problem you do not have. The tools that matter for copper corrosion are pH and alkalinity correction at the point of entry, and they are a different piece of equipment entirely.
Why Some Pipes Go and Others Do Not
Water chemistry sets the background risk. What decides which specific length fails first is usually something mechanical.
| Factor | Why it accelerates pitting |
|---|---|
| Heat | Corrosion reactions speed up with temperature. Hot lines and the first few metres off a water heater are the most common failure points in a house. |
| Recirculating loops | Constantly moving hot water combines heat with velocity. Buildings with hot water recirculation see disproportionate copper failure. |
| Water velocity | Undersized pipe or aggressive pump pressure scours the inside wall and strips any protective film that has formed. |
| Flux residue | Excess soldering flux left inside a joint stays corrosive after installation. This is a workmanship problem, not a water problem, and it produces failures clustered near fittings. |
| Thin-wall tube | Type M has less wall thickness to lose than Type L before a pit becomes a hole. |
| Grounding faults | Electrical current travelling on a plumbing system that is acting as a ground path drives corrosion at the point where it leaves the pipe. |
Warning Signs Worth Acting On
- Blue-green staining in a tub, sink, shower base or on grout. That colour is dissolved copper coming out of your pipe, and it means the water is taking metal with it.
- Green or white crust on the outside of an exposed pipe or fitting, often with a small dried mineral trail below it.
- A recurring damp patch on a ceiling or wall that dries out and comes back.
- Water meter movement with every fixture in the house shut off.
- A second leak within a year of the first, in a different part of the house. One pinhole is an event. Two is a pattern.
Water running behind a wall with nothing turned on? Shut off the main, avoid the electrical panel and any wet fixtures, and call (778) 562-5628 for 24 hour dispatch.
Repair Options
Spot repair
Cut out the failed section and join in new pipe. Appropriate for a first leak in an otherwise sound system, and it is what happens on an emergency call at midnight regardless of the longer-term plan.
Partial repipe
Replace the segment that is failing, most often the hot water distribution or a recirculating loop, and leave the cold lines in place. This is the practical middle ground when failures cluster in one part of the system.
Full repipe in PEX
Cross-linked polyethylene does not pit. In a home with repeat copper failures it removes the failure mode rather than managing it. The process is the same one described in our Poly-B piping guide: permit, planned access points, staged changeover, pressure test, inspection.
Point-of-entry corrosion control
For strata buildings and larger properties, a neutralizing system at the water main raises pH and adds mineral before the water reaches the building's distribution. This is the standard approach where replacing every riser is not realistic, and it protects new copper if a partial replacement has already been done.
Strata buildings. Repeat pinhole leaks in a multi-unit building are a shared infrastructure problem, not a series of unrelated unit incidents. Once leaks begin appearing in more than one unit, the council usually needs a plumbing assessment on record before the next budget cycle. See who is responsible for what in a strata leak.
Found a Stain You Cannot Explain?
Book an inspection and a technician will locate the leak, check the condition of the surrounding pipe and explain whether this is an isolated repair or the start of a pattern. The $60 inspection fee is credited toward the work once you approve the quote.
24 hour emergency dispatch. WaterLine Plumbing is licensed, bonded and insured, with an A+ BBB rating.
Common Questions
How long should copper pipe last here?
There is no single number. In water with normal mineral content copper routinely runs 50 years or more. In very soft, low-alkalinity water, service life is meaningfully shorter, and hot lines shorter again than cold. Installation quality moves the number as much as the water does.
Is blue-green staining a health concern?
The staining itself is an aesthetic effect of dissolved copper. Health Canada sets guideline values for copper in drinking water, and if you are seeing persistent staining the practical step is to have the plumbing assessed and, if you want certainty about what is in the water, have it tested.
Can a pinhole leak be patched with a clamp?
A repair clamp will stop water today. It does not restore the pipe, and the corrosion that made the first hole is still working on the wall on either side of the clamp. Treat it as a temporary measure, not a repair.
References
- Metro Vancouver, Corrosion Control Program: Copper Pipes Protection (fact sheet). Retrieved from metrovancouver.org.
- Metro Vancouver Update, Metro Vancouver's Corrosion Control Program. Retrieved from mvupdate.metrovancouver.org.
- Province of British Columbia, BC Plumbing Code 2024. Retrieved from gov.bc.ca.