Understanding Pipe Relining and Its Common Problems

Pipe relining is a trenchless technology that repairs damaged pipes by inserting a resin-saturated liner into the existing pipe, then curing it to form a new, seamless inner wall. While this method is highly effective for most pipe issues—corrosion, cracks, root intrusion—occasional problems can arise after installation. These problems often stem from installation errors, material defects, or pre-existing conditions that weren’t fully addressed. Understanding the typical issues and knowing how to systematically troubleshoot them can save homeowners significant time, money, and frustration.

In this guide, we’ll walk through the most common post-relining problems: reduced flow, odors, leaks, liner damage, and persistent clogs. For each issue, we’ll provide a detailed root‑cause analysis and practical troubleshooting steps. We’ll also cover preventative maintenance and when it’s time to call a licensed professional.

Common Problems After Pipe Relining – Detailed Overview

1. Reduced Water Flow or Recurring Blockages

One of the most frequent complaints after pipe relining is noticeably slower drainage or complete blockages. This can happen for several reasons:

  • Improper liner inversion or curing that leaves a partial obstruction (a “fold” or “lump”) inside the pipe.
  • Debris trapped during installation (e.g., mud, stones, or old pipe fragments that weren’t fully cleared).
  • Liner thickness that is too great in relation to the original pipe diameter, effectively reducing the cross‑sectional area.
  • Grease, hair, or soap scum buildup on the new lining surface, especially if the liner wasn’t smoothed properly.

Troubleshooting Steps for Reduced Flow / Blockages

  1. Perform a CCTV inspection – This is the most reliable way to see inside the pipe. Look for any visible obstructions, liner folds, or resin drips that might be narrowing the pipe.
  2. Use hydro‑jetting – Professional hydro‑jetting can clear soft blockages (grease, soap) without damaging the cured liner. Avoid drain snakes or chemical cleaners until you know the nature of the blockage, as these can sometimes scuff the liner.
  3. Check for liner folds – If the CCTV shows a fold that is blocking flow, a small robotic cutter may be used to trim it. This should only be done by a trained technician.
  4. Verify pipe diameter – Compare the original pipe diameter to the relined diameter. If the liner reduced the internal bore by more than 10–15%, re‑lining a larger diameter pipe or using a thinner liner may be necessary.
  5. Flush with hot water – For mild grease buildup, running hot water for several minutes can help dissolve fatty deposits.

2. Unusual Odors from Drains

Foul smells emerging from sinks, showers, or floor drains after pipe relining are concerning but usually traceable. The lining material itself (epoxy or vinyl ester) has a strong odor during curing, but that should dissipate within 24–48 hours. Persistent odors often indicate:

  • Trapped debris decaying between the old pipe wall and the new liner.
  • Bacterial growth in areas where the liner didn’t fully adhere, creating a crevice for organic matter.
  • Improper plumbing venting – If the relining project altered the vent stack or a vent was blocked during installation, sewer gases can back up.
  • P‑trap issues – The liner may have covered or reduced the trap’s water seal, allowing gas to escape.

Troubleshooting Steps for Odors

  1. First, confirm the liner is fully cured – A slight epoxy smell is normal for a day or two. Run water for 5 minutes to flush any lingering fumes.
  2. Inspect the pipe with a camera – Look for gaps between the liner and the host pipe where sewage or debris might collect.
  3. Check all vent pipes – Ensure no vents were accidentally capped or crushed during the relining process. A simple test: if you pour water down a drain and hear a gurgling sound, the vent is likely partially blocked.
  4. Pour water into little‑used drains – If a trap has dried out, refill it. If the odor persists, try pouring a cup of white vinegar followed by hot water to kill bacteria.
  5. Seal small gaps – If the CCTV reveals a gap between the liner and the host pipe, a professional may inject a small amount of epoxy or use a spot repair liner to seal it.

3. Leaks or Water Seepage Around the Relined Pipe

Leaks can occur at pipe joints, at transitions between the relined section and original pipe, or through the liner itself if it was punctured or improperly cured. Even a small pinhole can cause water damage over time.

Common Causes of Leaks After Relining

  • Incomplete curing – If the resin wasn’t cured long enough or at adequate temperature, it remains soft and prone to leaks.
  • Debris or moisture trapped beneath the liner – This prevents a proper bond, creating channels for water to seep.
  • Mechanical damage – Sharp objects (rocks, tools) may have punctured the liner during or after installation.
  • Joint misalignment – The liner may not have extended fully into adjoining pipe sections, leaving gaps.

Troubleshooting Steps for Leaks

  1. Locate the leak source – Use a CCTV camera to inspect the entire relined section. Mark any areas where water appears to seep through.
  2. Check for voids or air pockets – A technique called “air‑testing” can help determine if there are gaps between the liner and the pipe wall.
  3. Apply a patch using a spot‑repair liner – For small, isolated leaks, a short length of cured‑in‑place patch can be installed by a professional.
  4. Re‑cure if the liner is still tacky – In some cases, applying additional heat (via hot water or steam) can complete the curing and seal minor leaks.
  5. Excavate if necessary – If the leak is at a connection where the liner didn’t bond to a fitting, or if the liner has a large tear, the only reliable fix may be to dig up the pipe and replace that section.

4. Cracks or Damage to the Relining Material

Although cured‑in‑place pipe (CIPP) liners are strong, they can still crack under certain conditions. Ground settlement, tree root pressure, or manufacturing defects can cause longitudinal or circumferential cracks.

Signs of Liner Damage

  • Water stains or mold on walls near the pipe route.
  • Sudden increase in water bills (hidden leak).
  • CCTV images showing linear fractures or “spider‑webbing” in the liner surface.

Troubleshooting Steps for Cracks

  1. Immediately stop using the drain – Flushing water through cracked liner can worsen the damage and lead to pipe collapse.
  2. Have a structural assessment done – A professional can determine if the cracks are cosmetic or structural. Flexible liners often accept small hairline cracks without leaking, but deeper cracks require repair.
  3. Install a structural liner repair – A short section of new liner can be installed inside the old one, sealing the crack from the inside.
  4. Address external causes – If tree roots are pressing on the pipe, they must be removed and the pipe encased in concrete or replaced. If ground movement caused stress cracks, consider soil stabilization or pipe re‑routing.
  5. Replace the entire relined pipe if damage is extensive – When a liner is cracked in multiple places, the entire section may need to be excavated and replaced with new pipe or re‑lined.

5. Persistent Backups or Slow Drains

A backup (wastewater rising in a fixture) is more serious than simple slow drainage. It often indicates a complete or near‑complete obstruction downstream. After relining, this can be due to the liner itself being too narrow, or because the installation team left a collapsed section upstream.

Troubleshooting Steps for Backups

  1. Use a CCTV camera to navigate past the backup point – This will show whether the obstruction is within the relined section or further downstream.
  2. Hydro‑jet the line – High‑pressure water can clear most soft clogs and reveal if the liner is clear.
  3. Verify the liner was installed to the correct diameter – If the liner shrank slightly during curing, the functional pipe diameter may be too small for the fixture loads. A pipe redesign or re‑lining with a different material may be required.
  4. Check for grade issues – If the relined pipe now has an insufficient slope (e.g., because the liner created a slight sag), water won’t flow properly. This may require re‑grading the pipebed or installing a new alignment.
  5. Consult the original installer – Many companies offer a warranty. If the backup occurs within the first year, the installer should re‑inspect and correct at no cost.

Preventative Maintenance After Pipe Relining

Once your pipe is properly relined, following a maintenance routine can greatly extend its lifespan—typically 20–50 years or more.

Regular Inspections

Schedule a CCTV inspection every 2–3 years, especially if you have large trees near sewer lines or if the pipe carries grease‑producing kitchen waste. Early detection of root intrusions or lining defects allows for simple, low‑cost spot repairs.

Mindful Drain Usage

  • Never flush non‑degradables – Baby wipes, feminine products, paper towels, and even “flushable” wipes can accumulate on the smooth liner surface and eventually form blockages.
  • Use strainers in sinks and showers to catch hair and food particles.
  • Limit chemical drain cleaners – Harsh chemicals (sulfuric acid, lye) are unnecessary for a relined pipe and can damage the epoxy over time. If you need to clear a slow drain, use a plumber’s snake or hydro‑jetting.
  • Flush with hot water weekly – A bucket of hot (not boiling) water poured down each drain helps dissolve soap scum and grease.

Professional Cleaning

If you notice any slowing of drains, hire a professional for hydro‑jetting rather than using off‑the‑shelf liquid cleaners. Hydro‑jetting thoroughly scrubs the liner’s interior without damaging it, restoring full flow instantly.

When to Call a Professional

While many troubleshooting steps can be performed by a handy homeowner, certain situations absolutely require a licensed plumber or a relining specialist:

  • You see water damage (stains, mold, or wet spots) in walls, ceilings, or floors.
  • The CCTV camera shows large cracks, collapsed sections, or gaps.
  • Odors persist after cleaning and flushing, indicating a possible vent problem or trapped sewage.
  • You have repeated backups that return after clearing.
  • The relining work is still under warranty – always call the original installer first. Many companies offer a 5‑ to 10‑year labor and material warranty.

Professional plumbers have specialized equipment: robotic cutters for liner folds, heat‑curing units for spot repairs, and cameras capable of 360° inspection. They can also perform pressure tests to confirm the repair is watertight. This Old House provides a helpful overview of when pipe relining is the right choice and when excavation might be better.

Summary of Troubleshooting Flow

Here’s a quick decision flowchart for common post‑relining problems:

  1. Is water flowing slower than before? → CCTV inspection → If there’s debris or a fold, hydro‑jet or trim. If the diameter is too small, consider re‑lining with a thinner liner.
  2. Do you smell sewer gas? → Check vents and traps. If no vent issue, inspect liner for gaps. Seal small gaps with epoxy.
  3. Is water leaking (visible or in water bill)? → CCTV find → If it’s a pinhole / small crack, patch with spot liner. If extensive, replace section.
  4. Is the liner cracked? → Assess structural integrity → Small cracks can be sealed; large cracks require a structural liner replacement.
  5. Do you have backups? → Clear with hydro‑jet. If backups recur, check grade and liner diameter. Consult a professional.

Pipe relining is a proven, durable solution when performed correctly. By systematically troubleshooting issues and performing regular maintenance, you can enjoy a trouble‑free drainage system for decades. For further reading on pipe relining best practices, Epoxy.com’s guide on common relining mistakes offers additional insights, and Trenchlesspedia’s technical overview can help you understand the process in depth.

Remember: when in doubt, always call a professional. A small investment in expert help now can prevent costly water damage and a full‑blown pipe replacement later.