Sewer Network Installation: Step-by-Step Guide for London Sites

When you build or refurbish in London, a well-planned foul sewer network is the difference between a smooth Building Control sign-off and months of disruption. Below is how our team delivers small-to-mid scale sewers for residential blocks, basements and extensions—sequenced for tight urban streets and live services.

What we install (typical scope)

• uPVC/VC or concrete foul pipes sized from 160–315 mm ID, with manholes to suit depth and flow. Quantities, diameters and manhole types are driven by the drainage design and Building Control/Thames Water requirements. 

Our delivery sequence (field-tested)

1. Pre-start approvals & survey
   Confirm shop drawings, permits and traffic management. Set out line/level at 10 m intervals and dig trial pits to locate live services.
2. Traffic & safety setup
   Implement barriers, signage and trench support where required; coordinate with the highways team if carriageway works are needed. 
3. Excavate trenches
   Excavate to formation, maintaining design gradient and trench width. Protect any exposed utilities and keep them operational. 
4. Bed & level
   Prepare pipe bedding and formation with plate compaction; confirm gradients with survey kit and on-site tests. 
5. Manholes
   Seat bases on 100 mm blinding; stack rings/plastic chambers plumb and watertight; waterproof internal/external walls where specified; form benching after successful tests. 
6. Pipe laying (upgrade)
   Lay from downstream manhole “up-grade” to maintain falls; align with rope/mirror checks before surround is completed. 
7. Hydraulic/watertightness testing
   Plug ends, fill to head, hold a minimum period (typically ~2 hrs in the referenced method), and verify no loss before backfill. Vertical slopes can be verified with a rolling ball where applicable. 
8. Backfill & compaction
   Surround and backfill in 300 mm layers to ≥95% of standard Proctor (as specified), reinstate sub-grade to suit the next trade, and place warning tape 500 mm above the pipe. 
9. Connections & handover
   Make core-drilled connections into existing manholes; clean through the network; record tests and as-built levels for Building Control/Thames Water.

Quality records we keep

Daily reports, inspection/test records, weather logs, change orders, and technical queries—so your file is audit-ready for sign-off and future maintenance. 

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Why clients pick AmtaarGC for sewers

• Tight-site expertise: trench support, live services, and traffic management without shutting your project down.
• QA you can show inspectors: pre-set ITPs, compaction results, and hydraulic test certificates linked to chainage.
• One team from drawing to reinstatement: we coordinate with your architect/structural engineer and handle handover packs.