Buying a home is one of the biggest investments you’ll ever make. A property viewing and building inspection can reveal plenty about the house, but they may not show what is happening beneath the ground.

Underground drains can be cracked, blocked, displaced or damaged without any obvious sign inside the home. A pre-purchase drainage inspection gives Christchurch homebuyers a clearer picture of the condition of the property’s sewer and stormwater pipes before they commit to the purchase.

What is a pre-purchase drainage inspection?

A pre-purchase drainage inspection uses specialised CCTV camera equipment to inspect the inside of accessible underground pipes. A small camera is fed through a suitable access point and guided through the drainage system while the operator reviews the footage.

The inspection may identify:

• Cracked or broken pipes
• Collapsed or partially collapsed sections
• Displaced or separated joints
• Blockages and built-up debris
• Intrusive tree roots
• Silt or groundwater entering the pipe
• Damaged connections
• Poorly graded or incorrectly connected pipework
• Older pipes showing signs of deterioration

Depending on the property and the scope of the inspection, the camera may be used to assess sewer, wastewater or stormwater drains. These systems are separate, so checking one does not automatically confirm the condition of the other.

Why should Christchurch buyers have drains inspected?

Christchurch has many older homes with established gardens, mature trees and underground infrastructure that has been in place for decades. The Canterbury earthquake sequence caused significant ground movement that affected private drainage systems in some properties – breaking the main drainage pipes and often breaking pipes connecting individual properties to the city drainage system.

A house may have had previous repairs, an EQC or insurance claim, or no known history of drainage problems at all. None of these circumstances proves that the current drainage is sound.

Ground movement can cause pipes to:

• Crack or fracture
• Shift at their joints
• Separate from connections
• Lose their original fall
• Allow groundwater or silt to enter
• Become more vulnerable to blockages

Some drainage problems take years to become obvious. A pipe may continue to function while allowing roots, soil or groundwater to enter. By the time a blockage, overflow or damp patch appears, the repair may be more disruptive and expensive.

Old terracotta and earthenware pipes

Many older Christchurch properties contain terracotta, clay or earthenware drainage pipes. These materials were commonly used before modern PVC pipe systems became widespread.

Old terracotta pipes are not automatically defective. Some remain serviceable for many decades. However, age, ground movement, tree roots and deteriorating joints can increase the risk of problems.

The Pooman team can carry out a CCTV inspection on the property, which may identify:

• Cracks and fractures
• Open or displaced joints
• Root intrusion
• Deformation or collapse
• Silt entering through damaged sections
• Areas where debris is catching
• Evidence of repeated repairs

If the property you wish to purchase has older pipework, a pre-purchase inspection can help you understand whether it is in reasonable condition, needs cleaning, requires localised repair or may need relining or replacement in the future.

Understanding the limits of CCTV inspections

A CCTV inspection is valuable, but it is not a guarantee that every drainage issue has been ruled out.

The camera can only inspect sections that are accessible and passable. The inspection may be limited by:

• Blockages
• Collapsed pipe sections
• Inaccessible or missing access points
• Poorly designed drainage layouts
• Pipe sizes or conditions that prevent camera travel
• Connections that cannot be reached
• Sections outside the agreed inspection scope

A report should explain which drains were inspected, how far the camera travelled and whether any areas could not be reached.

CCTV also focuses on the inside of the pipe. It does not automatically assess the condition of surrounding soil, foundations, retaining walls, ground stability or every underground service on the property. Additional building, structural, geotechnical or plumbing advice may be needed depending on what is found.

Earthquake-related drainage damage

The Canterbury earthquakes affected buildings, roads, foundations and underground services across Christchurch. Private sewer and stormwater pipes can also be affected by settlement, lateral movement and changes in ground level.

Earthquake-related drainage damage may include cracked pipes, displaced joints or separated connections. It may not be visible from the surface, particularly if the pipe is still carrying water.

When buying a Christchurch home, ask the vendor or agent:

• Was the property affected by the Canterbury earthquakes?
• Was there an EQC or insurance claim?
• Were drainage repairs completed?
• Is there documentation showing what was repaired?
• Were only localised sections repaired, or was the whole line replaced?
• Have there been recurring blockages, overflows or drainage issues since the repairs?

A CCTV inspection can identify current defects that may be consistent with ground movement. However, CCTV footage alone cannot confirm when or why damage occurred. If a defect may relate to an earthquake claim, obtain appropriate advice from your insurer, solicitor or a suitably qualified expert.

Intrusive tree roots

Christchurch’s established sections often include large trees close to homes, driveways and underground services. Tree roots are attracted to moisture and can enter drainage pipes through cracks, failed joints or gaps around connections.

Once inside, roots can catch toilet paper, grease, silt and other debris. This can lead to repeated blockages and slow drainage.

Root cutting or high-pressure water jetting may clear the immediate blockage, but it may not fix the damaged pipe that allowed the roots to enter. Depending on the condition and location of the pipe, the long-term solution could involve localised repair, pipe relining or replacement.

When should you arrange an inspection?

A pre-purchase drainage inspection is most useful while your offer is still conditional and before settlement. It can be arranged alongside a building inspection, but it is a separate service with a different purpose.

Consider booking one when:

• The property is older
• The drains are made from terracotta, clay or earthenware
• Mature trees are close to the house or drainage routes
• The property has a history of earthquake damage
• There have been recurring blockages or overflows
• Drainage repairs are mentioned in the property documents
• The home has extensions or renovations
• Drainage plans or as-built information are unavailable
• There are low-level rooms or signs of dampness
• You are buying an investment property and want to understand future maintenance risks

How a drainage report can help with negotiations

Finding a drainage defect before settlement gives you information and options. Depending on the seriousness of the issue, you may be able to:

• Ask the vendor for further information
• Request previous repair or claim documentation
• Obtain an estimate for the required work
• Renegotiate the purchase price
• Ask the vendor to complete repairs before settlement
• Include specific requirements in the sale and purchase agreement
• Decide that the property is not suitable for you

A written report and supporting CCTV footage can provide useful evidence during these discussions. It does not replace legal advice, so speak with your solicitor or conveyancer before changing the terms of your agreement.

What should a pre-purchase drainage report include?

Before booking, ask what will be provided. A useful report may include:

• Property address and inspection date
• The type of drainage inspected
• Access points used
• Pipe sections reached by the camera
• Defects identified
• Still images or video footage
• The location of significant defects, where identifiable
• Recommendations for repair or further investigation
• Any limitations affecting the inspection

The report records the condition of the accessible drainage at the time of inspection. It cannot guarantee that an inaccessible section is defect-free or that future blockages, root growth or ground movement will not occur.

Why book Pooman for your pre-purchase drainage inspection?

Pooman provides residential and commercial drainage services throughout Christchurch and surrounding areas, including CCTV inspections of sewer and stormwater pipes.

Our CCTV drain camera technology helps identify hidden problems such as tree-root intrusion, built-up waste, cracked pipes, damaged joints and collapsed sections. If an issue is found, our experienced drainlayers can explain the practical repair options and advise whether further investigation is needed.

Pooman is a Registered Master Drainlayer and approved Christchurch City Council contractor, with experience across CCTV inspections, pipe repairs, root removal, pipe location, drainage replacement and related drainlaying services.

Protect your investment before settlement

A home can look perfect above ground while hiding expensive drainage problems below it. Old terracotta pipes, earthquake-related movement, intrusive tree roots and damaged stormwater systems may not be visible during a viewing or standard surface inspection.

A pre-purchase CCTV drainage inspection gives you better information before you sign on the dotted line. It can help you understand the condition of the pipework, plan for potential costs and negotiate from a more informed position.

Protect your investment. Contact Pooman to book a pre-purchase drainage inspection in Christchurch.