Older properties across Portsmouth often share one hidden feature beneath their gardens or driveways: a Buchan trap, also known as an interceptor trap. Designed in the late-Victorian era to block sewer gases from entering homes, these bent clay or cast-iron fittings are now a leading cause of blocked drains Portsmouth wide.
What Is a Buchan Trap?
A Buchan trap is a U-shaped section of pipe set into the foul drain near the property boundary. Water permanently sits in the bend, acting as a seal against odours rising from the main sewer. While ingenious for its time, it has become outdated for two reasons:
- Modern wastewater treatment plants control odours far more effectively than in the 1800s.
- The trapped bend creates a choke-point that collects debris, wipes and fat, leading to blockages.
Why Most Older Portsmouth Homes Still Have One
Large areas of Southsea, Fratton and North End underwent rapid development between 1880 and 1930, when building regulations called for interceptor traps in every new drain. Many were never removed, so today’s owners inherit an unseen liability:
- Narrow clay or cast-iron construction
- Sharp 90-degree bends that collect waste
- Often hidden beneath concrete or tarmac, making access difficult
Common Problems Caused
- Slow flow and regular blockages (especially wipes, fat and silt)
- Flooding of the upstream pipework during heavy rain
- Cracking of the trap due to ground movement, causing leaks
- Root intrusion through joints and hairline fractures
These issues typically appear as repeat call-outs for a blocked drain Portsmouth homeowners experience every few months.
How Portsmouth Drains24 Diagnoses and Fixes Buchan Traps
Drain survey Portsmouth service
Our engineers carry out a high-definition CCTV drain survey to confirm if a Buchan trap exists, assess its condition and locate any fractures.
Trap removal or CIPP relining
Depending on access and pipe layout, we offer two compliant solutions:
- Remove and replace the trap with a straight pipe section, reinstating the surrounding surface.
- CIPP (Cured-In-Place Pipe) lining to create a smooth, watertight internal sleeve. This seals cracks, bypasses the U-bend restriction, and prevents future root ingress—without excavation.
Both options restore full bore flow, reduce future maintenance, and keep the system legal under Building Regulations Part H.
Why Choose Portsmouth Drains24
- No call-out fees and fixed quotations
- NADC- and WJA-certified engineers
- 24/7 emergency response for blocked drains Portsmouth properties
- Full digital reports for insurance or building control
Act Before the Next Blockage
If you live in an older Portsmouth property and suffer repeat slow drains or backups, a hidden Buchan trap may be to blame. Book a CCTV inspection with Portsmouth Drains24 to find out—and get a safe, lasting repair.
