What a pinhole leak looks like and why it forms
Early signs are quiet. A green or white crust on the pipe, a damp spot on drywall, a faint hiss in a wall or a water bill that creeps up with no change in habits can all mean a pinhole. A stained ceiling below a bathroom often means the leak has been going for a while.
Several causes can wear a hole through the wall of copper tubing. Fast or turbulent water scours the inside of elbows and tees. Pitting can start where the water chemistry or leftover flux attacks the metal. Outside moisture, contact with other metals and thin tubing add to it, and often more than one cause is at work.
A plumber can see which pattern you have. A single pit near a fitting suggests a local flaw. Pits spread across a long straight run suggest the whole pipe is aging.
Soldered, push-fit or press: how the three repairs compare
All three methods can make a lasting repair when installed correctly. The right one depends on the space, the moisture in the pipe and how many joints the job needs.
| Method | How it seals | Best use | Limits |
|---|---|---|---|
| Sweat solder | Heat draws molten solder into a cleaned joint | Permanent joints in open, dry, reachable runs | Pipe must be dry, and flame near framing needs care. |
| Push-fit | Stainless teeth grip the pipe and an O-ring seals it | Fast repairs in tight spots or wet pipe | Pipe end must be clean, round and fully inserted. |
| Press | A power tool crimps the fitting over a sealing ring | Many joints in one job, including damp pipe | Needs the tool and clearance around the joint. |
| Repair clamp | Rubber sleeve and screws squeeze the hole shut | Temporary hold until a real repair | Not a lasting fix, so plan to replace it. |
A pinhole in copper rarely stays small, so call (336) 453-0472 if you see green crust or beads of water.
Repair or replace: a decision guide
One pinhole in clean pipe, with smooth walls and no crust beyond the leak, is a repair. The plumber cuts out the damaged section and joins in a coupling or a short new piece. The rest of the run is probably sound.
Replace the run when the pattern says the wall is gone. A new leak weeks after a repair, rough or pitted pipe on the inside, or a second pinhole on the same line all point that way. Opening drywall again and again is a poor trade, and repiping the affected run is usually the sounder decision. For an active leak that cannot wait, our burst pipe repair team can stop the water first and talk through the longer fix.
Cutting into a wall or ceiling is part of any honest quote, so ask what the plan is for drywall and who handles the finish work.
- Repair: one leak, firm pipe, no green crust along the length.
- Repair first, watch closely: two leaks on separate runs a year or more apart.
- Replace the run: several pinholes, pitted walls or repeat leaks at old patches.
- Replace and ask questions: leaks on both hot and cold lines in the same house.
Shutting off and draining before any repair
- Close the main valveTurn off the shutoff where water enters the house, or at the meter box if you cannot find it. Turn it firmly to the closed position and do not force a stuck valve.
- Open the tapsOpen the highest faucet to let air in and the lowest faucet to let the line drain. Flush a toilet once to empty the tank on the affected line.
- Protect the water heaterIf the leak is on a line that feeds the water heater, switch off its power at the breaker or set a gas unit to pilot so it does not run while water is low.
- Dry the pipeSoldering needs a bone-dry joint, because trapped water turns to steam and blows out the solder. Push-fit and press fittings tolerate more moisture, but read the manufacturer's instructions.
- Restore water slowlyOpen the main valve a quarter turn, let the lines refill and check the repair with a dry paper towel. Run each faucet until air stops sputtering, then look again an hour later.
Test your tap if pinholes keep coming back
Water testing is something a homeowner can arrange alone, and it costs far less than replacing pipe on a hunch. Collect the sample at a cold tap that has sat unused overnight, and follow the lab's instructions. We also repair and replace copper for homes in Lewisville and the rest of our service area, and we explain the price before work starts.
If a house has had more than one pinhole in a few years, test the water at the tap for pH, chlorine and dissolved minerals, then compare the result with your supplier's report. A test tells you whether the water is part of the story. Without it, blaming the utility or the pipe is only a guess.
Clemmons plumbing note: what the utility report says about pH
The Winston-Salem/Forsyth County Utilities 2025 Water Quality Report lists pH from 6.4 to 8.0 with an average of 7.5, and lead and copper at the tap both non-detect at the 90th percentile. An average near 7.5 gives no reason to blame the utility for pinholes in your pipes. The range is wider than the average, so a test at your own tap is the only way to see what your pipes get.
Check your bill to see who supplies your water, because some properties use private wells. Well water chemistry differs from the utility's numbers, and the report does not describe it. If you are on a well, test the well.
Source: Winston-Salem/Forsyth County Utilities 2025 Water Quality Report.
Frequently asked questions
Can I fix a pinhole leak with epoxy or a clamp?
A clamp or putty can slow a leak for a day or two. Neither is a lasting repair, and a damp wall behind the patch can grow mold. Use them only to buy time until a plumber cuts in a proper coupling.
Is a push-fit fitting acceptable inside a wall?
Read the manufacturer's installation instructions first, since they say where the fitting may be used and whether it can be covered. For permit questions, ask the Winston-Salem/Forsyth County Inspections Division at 336-727-2624.
Does Clemmons water cause pinhole leaks in copper pipe?
The utility's reported pH averages 7.5, so the report alone does not point a finger at the water. Other causes are common, and homes on private wells have different water. Test your tap before deciding.
How long can I leave a pinhole leak before fixing it?
Not long. A pinhole can wet framing, insulation and drywall steadily, and the damage and the water bill both grow. Shut off the line if you can and arrange a repair as soon as possible.
Should I replace all the copper after one pinhole?
Usually not. One pinhole in healthy pipe is a repair. A plumber looks at the surrounding pipe and tells you whether the whole run is worn.
Standards and sources
This guide was written by Clemmons 24/7 Plumbing using general trade practice and the sources named in the local note above. For code questions, the standard to check is the North Carolina State Plumbing Code together with the manufacturer instructions for your product.
Written by Clemmons 24/7 Plumbing. Questions about permits or inspections go to the Winston-Salem/Forsyth County Inspections Division at 336-727-2624, and questions about the water on the utility side of your meter go to your water provider.