Pinhole Leak Assessment and Repipe Recommendation

Purpose

A pinhole is a sample, not an event. It treats the hole the customer called about as one data point from a system carrying the same water at the same temperature and velocity, and ends with a written failure rate, a named mechanism, and a repipe verdict against a stated gate. Skip it and the shop solders a coupling, invoices a small repair, and returns three more times over two years, each time calling this one unrelated. It prevents the opposite error too: a repipe sold off one hole a nail or a hanger explains completely.

Scope

Covers assessment of a pressurized potable copper system in a house, small office, small retail space or multifamily unit after one or more pinhole failures, and the recommendation that follows.

Does not cover executing the repipe (the repipe of an occupied home phasing SOP), polybutylene or PEX-AL-PEX, whose failures are a fitting problem rather than a tube problem (the polybutylene and legacy material assessment SOP), a leak nobody has located (acoustic and tracer gas leak location), or an active flood (burst pipe emergency response).

Roles and the handoff

Procedure

1. Answer the water-and-electricity question before touching a tool. Look for standing water or spray near a receptacle, panel, furnace or appliance cord. Acceptance: a written yes or no with a time, before any cutting. Wrong: a tech on a wet floor with a torch lit. Stop rule: where water and energized equipment share a space nobody works there until a qualified person under 29 CFR 1910.332 and 1910.399 isolates the circuits per 29 CFR 1910.333(b)(2), and if nobody on site is qualified it goes to an electrician. Hazard: this step is the hazard, which is why it runs first.

2. Isolate, bond across the cut, drain, and cut a coupon you can read. Close the upstream valve, open a low fixture, clamp a temporary bonding jumper of adequate size to clean metal each side of the intended cut, then cut 3 in of tube centred on the hole with a fine-tooth saw. Acceptance: both jumper clamps tight on bare metal before the blade moves, the run empty, and the hole intact with the bore uncrushed, bagged and labelled with location and side. Wrong: a wheel cutter rolling the wall inward, closing the pit you came to read. Stop rule: a crushed coupon is not evidence, so cut a second before the wall closes; a jumper that will not bite clean metal stops the cut until it does. Hazard: a metallic water line can be carrying neutral or fault current, which crosses you the moment the last strand parts, so the jumper goes on before the blade and stays on through the repair, the permanent connection being restored at step 9 per NEC Article 250 in the edition your AHJ has adopted; hot-side pipe also sits at 120 to 140 F and 140 F water scalds in seconds, so drain to a bucket first.

3. Read the pit from the inside and name the direction of attack. Split the coupon lengthwise, or look down the bore with a light and loupe. Acceptance: the pit described as bore-outward or exterior-inward, a pit count on that coupon, and what the bore carries. Wrong: calling every hole a pinhole; an external groove with bright bore metal is mechanical. Stop rule: one pit, exterior-in, on a clean bore ends this procedure at a repair. Hazard: splitting a coupon throws chips, so eye protection with side shields, and never wire-wheel the bore clean, which destroys the evidence and raises metal-oxide dust into your breathing zone.

4. Count the independent prior failures and date each. Walk visible piping for old couplings, sweat repairs, clamp scars and patches, and pull the address history. Acceptance: every entry supported by a visible repair or dated record, recollection logged separately as unverified. Wrong: taking "this happens all the time" as three. Stop rule: an unverified count does not feed the step 8 gate; write both numbers. Hazard: this puts you in crawlspaces, so stay on joists, and where piping wears pre-1980 thermal system insulation treat it as presumed asbestos-containing under 29 CFR 1926.1101 for construction work or 1910.1001 in general industry, noted on the ticket, and do not brush, cut or pull it.

5. Measure the hot-side velocity driver. Read the recirculation pump curve, note return tube size and type, and compute velocity. Acceptance: a figure in feet per second with the tube ID used, against about 2 to 3 fps on a continuously running return and roughly 5 fps on hot branch piping (Copper Development Association tube handbook practice). Wrong: "pump present" with no number. Stop rule: a return over the ceiling is a named mechanism and goes in the record whatever the verdict, because a repipe reusing that pump and return size pits again. Hazard: pump and return sit at tank temperature, so read the label in place and loosen no union.

6. Record static pressure and delivered hot temperature at named points. Gauge on a hose bib with fixtures closed, then a probe at the nearest hot tap after a 60 second run. Acceptance: a static psi with the gauge point named and a temperature with the tap named. Wrong: quoting the thermostat dial instead of measuring at a tap. Stop rule: static above the 80 psi ceiling the IPC and UPC carry in their water-supply chapters, in the edition your AHJ has adopted, adds the house pressure survey SOP as a parallel finding rather than replacing this one. Hazard: a hot line that has sat delivers a slug above setpoint, so run into the basin and keep hands clear.

7. Survey the exposed system for the same signature. Walk every accessible foot of the same material on the same side, feeling elbows and looking for green weeping stain and unopened scabs. Acceptance: exposed footage in feet with the count of stained or scabbed points on it. Wrong: a system-wide condition reported from one bathroom. Stop rule: where less than roughly a quarter of the run is accessible the rate stands on exposed footage only and the record says so. Hazard: where this needs a ladder, set the feet on a solid surface and tie off nothing to piping; otherwise none, recorded as checked.

8. Compute the rate, then write the verdict against the gate, per material class per side. The repipe gate is three or more verified independent failures within a rolling 24 months AND a step 3 mechanism of general internal attack, meaning bore-out pitting with more than one pit on the coupon. Both must be true. Acceptance: the division printed with both inputs, plus repipe, partial repipe of the affected side, or repair-and-recheck, naming which condition carried it. Wrong: repiping on one dramatic failure. Stop rule: exactly one condition met is repair-and-recheck at 6 months, never a soft repipe pitch. Hazard: none, a desk decision.

9. Repair, then put the water back and prove the building is as safe as you found it. Reopen the isolation valve a quarter turn at a time with a high fixture running. Acceptance: static back within about 5 psi of the step 6 reading at the same gauge point, every fixture running solid water, and no drip at any joint or valve you touched after a 10 minute settle. Wrong: snapping the valve open, which slams the system and drives loosened scale into fill valves. Stop rule: a valve that will not reseal is replaced today, because you introduced that failure. Hazard: soldering here is hot work in a closed cavity, so ventilate, keep flux fume out of your breathing zone, shield framing and insulation with a listed pad, extinguisher in reach, and stand a 30 minute fire watch after the last flame; where the cavity holds loose fill or unidentified insulation the joint is made mechanically rather than with a torch. Repressurizing then puts your face at a fresh joint, so crack the valve and stand out of its plane; and because you cut metallic water pipe the equipment bonding path through it is open, so bond across the cut and restore the permanent connection per NEC Article 250 in the edition your AHJ has adopted.

The record this produces

Eight fields, filed on the address rather than the invoice line: the water-and-electricity answer with its time; the coupon photo with location and side; pit direction and count; the verified failure count with dates plus the unverified figure beside it; return velocity with the tube ID used; static and delivered hot temperature with gauge and tap named; exposed footage with stained points; and the rate with its verdict and deciding condition.

The next tech reads the pit direction, because a second exterior-in hole in another room means a hanger problem, not a water problem. The velocity line is what stops a repipe being sold without correcting the pump and return size that caused the pitting, which is the most common way a repiped house pits again.

One worked pass, including a step that fails

Two-story house, 1988, type M copper, hot side recirculated. Complaint: a wet spot on the garage ceiling.

Step 1: no standing water near electrical, drip on bare concrete, logged 09:20. Step 2: upstream stop closed, tub spout opened, 4 in coupon cut from the hot branch with a hacksaw.

Step 3: split lengthwise, the bore shows four discrete pits in that 4 in, all opening bore-outward, blue-green deposit mounded over three and one perforated. Mechanism: general internal attack.

Step 4 FAILS its acceptance. The customer recalls "three or four" prior leaks. The walk finds one old sweat repair in the laundry ceiling and one clamp scar in the garage; office history holds one dated invoice matching it. Verified failures including today: 2. Unverified recollection: up to 4. The stop rule is taken, the unverified figure does not feed the gate, and both numbers go in the record.

Step 5: the return is 1/2 in type L, ID 0.545 in, and the pump's lowest speed is listed at about 4 gpm at this loop's head. Using v = 0.4085 times gpm divided by diameter squared: 0.4085 times 4 is 1.634, and 0.545 squared is 0.297, so 1.634 divided by 0.297 is 5.5 fps, against a 2 to 3 fps ceiling.

Step 6: 74 psi static at the laundry bib, inside the 80 psi ceiling. Hot delivered 141 F at the kitchen tap after 60 seconds.

Step 7: roughly 60 ft of hot side exposed across garage, laundry and a closet, three more green-stained scabs, none perforated. Well under a quarter of the run, so reported as exposed-footage-only.

Step 8: 2 verified failures over the 14 months between the dated laundry invoice and today. 2 divided by 14 is 0.143 per month, and 0.143 times 12 is about 1.7 per year on the hot side. The mechanism condition is met; the count condition is not, 2 against a gate of 3. Under the AND rule the verdict is repair-and-recheck, written as mechanism confirmed, count short, recheck at 6 months. The velocity finding is recorded as a correctable driver, since it stands regardless of the verdict.

Step 9: coupling soldered, stop reopened a quarter turn at a time with the tub running. Static reads 72 psi at the laundry bib against 74 psi on arrival, a 2 psi difference and inside the 5 psi acceptance. No drip after the 10 minute settle. The step 2 jumper stayed on through the repair, and the permanent bond was confirmed before it came off.

When the site does not match this procedure

A repipe is wanted today off one hole. Quote the repair and hand over the rate arithmetic. A count of one with a confirmed mechanism is a warning, not a gate; say so rather than selling on fear or dismissing it.

The failures are all cold side. Velocity is a hot-side story, so the drivers move to chemistry: pull the utility's annual water quality report into the record rather than concluding in the field.

Galvanized steel rather than copper. You are reading tuberculation and thread-root wall loss, not discrete pits, so run the pipe material identification and condition report SOP instead.

References

• Copper Development Association tube handbook, for design velocity practice on copper tube and returns.
• IPC and UPC water supply chapters, in the edition your AHJ has adopted, for the 80 psi static ceiling.
• 29 CFR 1926.1101 and 1910.1001 for thermal system insulation presumed asbestos-containing in buildings constructed no later than 1980; 29 CFR 1910.333(b)(2) with 1910.332 and 1910.399 for energized work.
• NEC Article 250, bonding, in the edition your AHJ has adopted.
• See related: repipe of an occupied home phasing; pipe material identification and condition report.