What Pipes Can Be Relined? Materials, Sizes and Limitations

Most Pipes Can Be Relined — But Not All

CIPP pipe relining is remarkably versatile. The technology was developed specifically to work inside existing host pipes of different materials, shapes, sizes, and conditions. For Central Coast homeowners, the practical answer to “can my pipe be relined?” is almost always yes — with a few specific exceptions that a CCTV inspection will identify.

Pipe Materials That Can Be Relined

Terracotta Clay (Vitrified Clay Pipe)

The most common pipe material in Central Coast homes built before 1982 — and the most common material we reline. Terracotta is an excellent host for CIPP liners because:

• The rough clay interior surface provides good adhesion for epoxy resin
• Terracotta’s circular cross-section accepts standard circular liners perfectly
• Even significantly deteriorated terracotta (cracked, root-infiltrated) can usually still be lined, provided the bore is accessible

Limitation: If the terracotta has fully collapsed (no bore remaining), the liner cannot enter. This requires excavation to access the collapse point.

Early-Formula PVC (1975–1990)

PVC pipe replaced terracotta as the standard residential material from the early 1980s. Early-formula PVC from the 1975–1990 era has joint issues — rubber ring joints that deteriorate, poor joint sealing that allows root entry — that are very suitable for CIPP relining. The PVC pipe wall itself is usually still sound; the problem is at the joints.

Liner adhesion note: Smooth PVC doesn’t bond to epoxy resin as strongly as rougher terracotta surfaces do. Liner installation techniques account for this — the liner is selected and installed to create an interference fit as well as a chemical bond.

Cast Iron

Used as junction fittings and short pipe sections in pre-1965 Central Coast homes, particularly in coastal suburbs (Avoca Beach, Terrigal, Point Frederick) where cast-iron components were standard for bathroom stacks and under-floor connections. Internal corrosion in coastal salt-air environments reduces the bore and increases flow resistance.

CIPP relining creates a smooth, corrosion-proof inner bore inside corroded cast iron — one of the most effective applications of the technology. The rough, pitted internal surface of corroded cast iron actually provides excellent resin adhesion.

Concrete Pipe

Used in stormwater systems and older larger-diameter sewer pipes (150mm+ in commercial and older residential applications). Concrete pipe is an excellent host for CIPP liners — solid structural shell, good surface for adhesion, and the circular cross-section accepts standard liner profiles.

Concrete stormwater pipes from the 1960s-80s era are common in Central Coast properties and are routinely relined.

Asbestos Cement Pipe

Used in some Central Coast drainage applications in the 1950s-70s. Asbestos cement can be relined, but requires specific handling protocols — the jetting and pre-lining preparation must be managed carefully to avoid generating asbestos-containing dust or particulate. We are equipped and trained to work with asbestos cement pipe under the relevant NSW Work Health and Safety requirements.

Note: Asbestos cement pipe relining requires additional time and cost due to the handling protocols involved.

Modern PVC and HDPE (Post-1990)

Newer-specification PVC and high-density polyethylene (HDPE) pipe can be relined if required. Issues in modern PVC/HDPE are usually at disturbed or incorrectly installed joints rather than material deterioration. Point repair (patch lining) is often the appropriate treatment for modern pipe joint issues rather than full-length relining.

Pipe Shapes That Can Be Relined

Circular (Standard Residential)

The vast majority of residential drainage is circular pipe (100mm, 150mm diameter). Standard circular CIPP liners are the most available, least expensive, and cover almost all Central Coast residential applications.

Egg-Shaped

Some older municipal sewer pipes and large stormwater pipes use an egg-shaped profile (wider at the bottom to maintain self-cleansing velocity at low flows). Specialised egg-shaped CIPP liners are available for this profile.

Rectangular / Box Culverts

Large stormwater culverts with rectangular cross-sections can be relined using flexible CIPP products formed to the rectangular profile. This is primarily a Council infrastructure application rather than private residential, but may be relevant for large commercial properties.

Pipe Sizes That Can Be Relined

For Central Coast residential properties, almost all work is in the 100mm diameter range (main sewer lateral) with some 75mm branch line work for kitchen and basin drains.

What CANNOT Be Relined

Fully Collapsed Pipe

If the pipe has completely collapsed — the host pipe walls have failed and the surrounding soil has filled the void — there is no bore for the camera or liner to travel through. This requires excavation to expose the collapse, remove the collapsed section, and either replace that section or (if a short section) make an access point for liner entry.

Note: Partially collapsed pipe — where the bore is reduced but some opening remains — may still be relinable if the remaining bore is sufficient for liner entry (typically 50%+ of original diameter).

Severe Offset Joints (30mm+)

A joint offset of more than 30mm creates a physical step in the pipe bore that the flexible CIPP liner cannot bridge without creating a significant restriction at the offset point. Minor offsets (under 15mm) are routinely relined without issue. Moderate offsets (15–30mm) require specialist assessment. Severe offsets (30mm+) typically require excavation to realign the pipe before lining can proceed.

Pipe Below Minimum Liner-Entry Size

Very small pipe bores (under 40mm) may not accommodate a camera or liner mandrel. For these situations (very old small-diameter branch drains), replacement is usually the only option.

Pipe in Situations Where Excavation Is Required for Other Reasons

Sometimes excavation is needed not because the pipe can’t be relined but because another repair on the same run requires access (a service connection that needs to be moved, a pit that needs to be rebuilt). In these cases, the excavated section may be replaced while the remaining sections are relined.

What Pipes Can Be Relined FAQs

Q: I have both terracotta and PVC sections on my sewer line (original + partial upgrade). Can it all be relined? Yes — CIPP liners span across different pipe material sections seamlessly. A run that changes from terracotta to PVC (or vice versa) at a joint can still be lined in a single liner installation. The liner bridges the material transition without any special treatment.

Q: My house is on a slope and the sewer pipe is buried quite deep at the bottom of the slope. Does depth matter? Depth affects excavation cost but does not affect relining viability (within normal pipe access). CIPP liners are inserted through access points at the pipe ends and travel horizontally through the pipe regardless of depth. Depth only becomes a relining factor if there are no accessible entry points at either end of the deep section.

Q: Can branch lines (kitchen, laundry, basin) be relined as well as the main sewer? Yes. 75mm and 100mm branch lines can be relined using appropriately sized cameras and liners. For kitchen drain branch lines in particular — which often accumulate grease — relining after thorough jetting can significantly improve flow performance and eliminate grease-related root intrusion at kitchen waste connections.

Q: Can a pipe that has already been relined once be relined again? Yes, in principle. Each relining cycle reduces the internal diameter by the liner thickness (typically 8–12mm in a 100mm pipe). A 100mm pipe can typically accept two or three relining generations before the diameter reduction becomes a flow concern.

Get a free CCTV assessment to confirm your pipe’s relining suitability →