Pre-Purchase Drain Survey in Cobham, Surrey
Alton Facility Services completed a pre-purchase CCTV drain survey for a residential property in Cobham, Surrey, giving the buyer a clear view of the drainage condition before purchase.
The survey identified serious foul drainage defects, root ingress, cracked clay pipework, a failed soakaway and a non-compliant septic tank that would require further remedial and compliance work.
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Project Overview
The customer requested a homebuyer drainage survey before committing to a property purchase. A key question was whether the drainage could be connected to mains drainage in future.
Our engineer attended site and carried out a CCTV inspection of the accessible foul drainage system. The survey confirmed that the drainage system discharged to a septic tank and that there was no nearby mains sewer connection available from the information found on site.
The inspection also confirmed that foul water and surface water were not combined. Surface water drainage could not be fully assessed because suitable access was not available, so the location and condition of that pipework remained unknown.
Quick Facts
- Service
- Pre-purchase drain survey
- Location
- Cobham, Surrey
- Property
- Private residential
- System
- Foul drainage and septic tank
- Date
- 18 June 2026
- Outcome
- Major defects and compliance risks identified before purchase
The Challenge
The buyer needed to understand the true condition of the drainage system before progressing with the property purchase. The drainage arrangement was more complex than a straightforward mains-connected system because the property discharged to a septic tank.
The site also had limited surface water access and areas of mature trees and vegetation around the private drainage system. This made the drainage survey important for identifying any hidden risk before purchase.
Why this survey mattered
A pre-purchase drain survey can identify defects, non-compliant off-mains drainage, failed soakaways and costly repairs before the buyer commits to the property.
Survey Findings
The foul drainage pipework was a combination of clay and UPVC, with most of the system made up of 100mm clay pipework. The condition of the pipework was poor in several areas.
- Multiple joint displacements were found in the foul drainage runs.
- Root ingress was present at several points, including the main line between FW3 and FW4.
- The camera survey recorded cracked pipework, holding water and bellies in the line.
- A section of pipework had dropped and would need repair.
- The main line to the interceptor was in poor condition and would require root removal and lining.
- FW3 had eroded benching and would require breaking out and re-benching.
Septic Tank and Soakaway Issues
The survey found that the existing septic tank was not compliant and was in poor structural condition. The tank was brick and render construction with several significant defects.
- Major cracking was visible within the tank structure.
- Dip pipes were missing.
- Brickwork and render had deteriorated.
- Some brickwork was missing.
- The soakaway had failed.
The recommendation was that the septic tank should be condemned and that a compliant treatment plant solution would be required. Because the septic tank was located in a wooded area, the report noted that a new system and drainage field would be better diverted to a more open area of the grounds.
Recommended Remedial Works
The drainage survey gave the buyer a clear list of defects and likely remedial work before purchase.
- Root cutting and high-pressure water jetting to remove root ingress.
- No-dig lining to repair the main foul drainage line after root removal.
- Repair of the dropped pipe section.
- Breaking out and re-benching FW3.
- Replacement of the non-compliant septic tank with a suitable treatment plant.
- Possible diversion of drainage to a more suitable open area for a treatment plant and drainage field.
Outcome
The buyer received clear evidence of the drainage condition, the septic tank compliance issue and the likely scope of future remedial works before committing to the property.
Survey Photos
Services Used on This Project
- Pre-purchase drain survey
- CCTV drain survey
- Homebuyer drainage inspection
- Foul drainage condition survey
- Septic tank inspection
- Drain defect reporting
- Root ingress and drain lining recommendations
- Off-mains drainage compliance advice
Buying a property with private drainage?
Arrange a pre-purchase drain survey before exchange so you understand the condition, compliance risks and likely repair costs.
