Quick Answer:
Dry the area, find exactly where water is coming from, and address that joint. Small leaks at unions or threaded adapters often come from misalignment or loose nuts and can be fixed by evenly tightening or reseating. If a sweat joint is weeping after soldering, you may need to re-sweat it or call a pro if you’re not comfortable with soldering.
Why This Happens
- New fittings shift pipe alignment. A union or threaded adapter can pull out of alignment during install and leave a small gap.
- Heat or movement can disturb soldered joints, causing a weep at a sweat connection.
- The PRV body or its adjustment screw can also leak if seals were disturbed during installation — consider the possibility of a separate internal leak such as PRV leaking from adjustment screw.
- Pipe strain: if the installed valve puts stress on nearby joints, that stress can open small leaks.
Step-by-Step What to Do
1. Turn off water and depressurize
- Shut off the main supply or the nearest shutoff valve. Open a downstream tap to relieve pressure and drain the line.
- Place a bucket or towels under the work area to catch drips.
2. Identify the exact leak location
- Dry the area completely with a rag and let it sit for a minute. Small weeps are easier to spot on dry metal.
- Check each possible source: union nut face, sweat joint seam, threaded adapter, and PRV body. Move the pipe slightly by hand to see if the leak changes.
3. Test and verify with a dry paper towel
- Wrap a dry paper towel around each suspect joint (one at a time). Turn the water on slowly and watch the towel for damp spots — this isolates which joint is leaking.
4. Tighten union nuts evenly
- If the leak is at a union, back the nuts off to finger-tight, then tighten in small increments, alternating sides to seat the gasket evenly.
- Use moderate force — snug first, then a small additional turn with the wrench. Re-test with the dry towel.
5. Re-sweat a weeping sweat joint (if you can do it safely)
- If a soldered joint is weeping, drain and dry the joint fully. Remove the fitting if possible, clean the pipe and fitting, apply flux, and re-solder using proper technique.
- If you’re not comfortable with torch work, or if nearby components could be damaged, call a professional.
6. Fix threaded adapter leaks
- For threaded adapters, shut off and disassemble the joint. Clean threads and reseal with appropriate thread sealant (pipe dope) or PTFE tape on the male threads, then reassemble and test.
7. Relieve pipe strain with proper supports
- Install pipe straps or clamps to support the pipe so the PRV and unions are not carrying load or shifted by gravity or movement.
- Ensure the PRV and fittings sit squarely — misalignment is a common cause of recurring leaks.
8. Final test and observation
- After adjustments, dry the area and do a final test with the dry paper towel method. Let the system run under normal pressure while you observe for several minutes.
- If the leak stops, leave the supports in place and check again the next day for slow weeps.
What Not to Do
- Don’t over-tighten unions; you can crack fittings and create worse leaks.
- Don’t apply an open flame near plastic piping, insulation, or the PRV internals — risk of damage or fire.
- Don’t assume the leak is from the PRV body without isolating other joints first. Tightening or soldering the wrong part can waste time and create new problems.
When to Call a Professional
- Leaks at the PRV body after you’ve checked unions and joints — internal seals may be failing.
- If soldering is required but you lack tools or experience, especially in tight spaces or near combustibles.
- Persistent leaks after tightening, resealing, and supporting the pipes, or if the leak is large and you cannot stop it safely.
Safety Notes
- Always shut off and depressurize before working on pressurized pipes.
- Wear gloves and eye protection when soldering or using tools.
- Keep a fire extinguisher nearby if using a torch and protect nearby materials from heat.
- If unsure about working on a pressure-regulating valve or if the plumbing is gas/plumbing combo, hire a licensed plumber.
Common Homeowner Questions
- Q: How do I know if the leak is from the PRV body or a joint?
A: Dry the area, isolate joints with a paper towel, and observe which spot gets wet first — that pinpoints the source. - Q: Can I use more thread tape to stop a threaded adapter leak?
A: Yes, but disassemble, clean threads, apply proper tape or pipe dope, reassemble, and test rather than piling tape on a tightened fitting. - Q: Is re-soldering a weeped joint a DIY job?
A: It can be if you have a torch and experience; otherwise call a plumber to avoid damage or fire risk.