Quick Answer:
If the line still runs slowly after a recent jetting, it’s often not a broken lateral. Start with simple checks: test nearby fixtures, inspect the P-trap, and open the nearest downstream cleanout to rod or camera the run. Jetting can dislodge grease, scale or debris that then lodges downstream — adding more pressure can make the problem worse. Follow the step-by-step checks below to find whether the issue is leftover debris or pipe damage.
Why This Happens
High-pressure water removes scale, roots and grease, but that material has to go somewhere. A jetting blast can:
- break loose chunks of scale or hardened grease that collect at a bend or transition;
- throw up solids that settle in a P-trap or a narrower section downstream;
- momentarily compress flexible tubing or displace poorly supported joints, causing a temporary restriction; or
- reveal—but not cause—existing damage in older pipes that now interferes with flow.
Step-by-Step What to Do
1. Run a quick flow test on nearby fixtures
Turn on each fixture closest to the cleaned section (sink, shower, toilet) and note if they all run slowly or only one. This tells you if the problem is isolated to a single trap/branch or affects the main lateral.
2. Inspect the P-trap and visible trap arms
Remove the P-trap under the slow fixture (use a bucket). Look for:
- freshly deposited grease, scoured scale, or bits of material that could have been blasted into the trap;
- signs the tubing has been crushed, distorted, or warped from the jet stream.
Clearing or replacing a damaged P-trap is an easy homeowner fix; large damage may require a plumber.
3. Open the nearest downstream cleanout and probe
Locate and open the closest downstream cleanout (outside or in the basement). Use a hand auger / hand rod first to see if you can dislodge remaining debris. If you have a small inspection camera, run it a few feet past the cleanout to check whether:
- there is a partial obstruction (grease ball, rag, scoured scale);\li>
- the pipe has cracks, offsets, or root intrusion; or
- the jetting simply washed material down to the next choke point.
4. Use targeted mechanical clearing or camera-guided cleanup when needed
If the camera or hand rod finds grease or solids thinned out by the jetting, use a mechanical method targeted to that material: a rotating cutter, a hooked rod, or camera-guided tools to retrieve or break up the choke point. Avoid increasing jet pressure as a first response — targeted work clears the remaining blockage without pushing material into deeper funnels.
5. Re-test fixtures after cleaning
After clearing, run the same flow test from step 1 to confirm improvement. If one fixture is still slow but others are fine, the issue is likely local (trap, stub-out, or branch). If multiple fixtures remain slow, proceed to professional help.
What Not to Do
- Avoid repeating high-pressure jetting without identifying the remaining obstruction — that can push material into deeper funnels or damage older clay pipes.
- Don’t stick your hand into a trap or pipe opening where sewage or sharp debris might be present; use tools and gloves.
- Call a pro when multiple fixtures remain slow after jetting or when you smell sewage; camera inspection often reveals whether pipe damage or residual debris is the cause.
When to Call a Professional
- If more than one fixture stays slow after you’ve checked traps and the cleanout — this is where a plumber’s camera and experience are most useful.
- If you detect sewage odor, repeated backups, or standing sewage — these are reasons to stop DIY work and call a pro immediately.
- If pipe material looks brittle, cracked, or you suspect a collapsed lateral — professional evaluation and possibly replacement will be needed.
- For broader household symptoms, see the related topic Multiple drains slow after cleaning for guidance on systemic issues and next steps.
Safety Notes
- Wear gloves and eye protection when opening traps or cleanouts; sewage can contain bacteria and sharp objects.
- Turn off nearby water to avoid unexpected flushing while you inspect or rod a line.
- Don’t mix chemical drain cleaners with mechanical methods — chemical residues can injure you or damage tools.
- If you smell strong sewer gas, ventilate the area and leave enclosed spaces before calling a professional.
Common Homeowner Questions
- My toilet and sink are both slow — is that a main line problem? Short answer: Possibly. If multiple fixtures drain slowly, it often points to a shared lateral or main; call a plumber for a camera check.
- Can I just jet again with higher pressure to finish the job? No. Higher pressure can push debris further down or damage older pipe materials; inspect first to identify the cause.
- What if I find grease in the P-trap? Remove and clean the trap, then use a targeted mechanical rod or camera-guided tool to clear downstream deposits rather than re-jetting immediately.
More in this topic
For more related fixes and similar symptoms, see Post-Snaking Main Line Problems.