PortCities London

Bazalgette and London's sewage

Bazalgette's system

Joseph Bazalgette

Once the enabling act was passed, the Metropolitan Board of Works could begin the task under the direction of its Chief Engineer, Joseph Bazalgette (1819-91).

Most schemes for removing London's sewage had planned to carry it inland so it could still be used as fertilizer, but Bazalgette realised this was impractical. Instead, he planned to build main sewers to collect the contents of the existing sewers and take their contents east to be discharged into the Thames.

Bazalgette's scheme

Bazalgette's scheme consisted of three major elements:

  • the intercepting sewers
  • the pumping stations and the outfall sewers
  • the pumping stations at Beckton and Crossness.

Each of these involved major feats of engineering.

From the intercepting sewers to the pumping stations

Deptford Pumping Station.
View full size imageDeptford Pumping Station. © NMM

On either side of the Thames, three main intercepting sewers captured the sewage from all existing sewers and carried them by gravity eastwards to the pumping stations at Abbey Mills (for the north bank) and Deptford (for the south). 

To the Thames via the outfall sewers 

The pipes of the Northern Outfall Sewer
View full size imageThe pipes of the Northern Outfall Sewer. © NMM
The pumping stations raised the sewage so it could be carried by gravity to the Thames. It flowed to the river in the massive pipes of the outfall sewers.

Building the Northern Outfall Sewer across the Plaistow Marshes.
View full size imageBuilding the Northern Outfall Sewer. © NMM

The outfall sewers were a massive feat of engineering. The Northern Outfall Sewer was more than 6.5 km (4 miles) long, and crossed the marshes east of the River Lea.

The Northern Outfall Sewer in Plaistow.
View full size imageThe Northern Outfall Sewer in Plaistow. © NMM

For most of its length, the Northern Outfall Sewer was concealed within a massive embankment. Several bridges carried it across the River Lea and its branches. The scale of the work is still impressive today.

The pumping station at Crossness.
View full size imageThe Pumping Station at Crossness. © NMM

The Southern Outfall Sewer ran underground for much of its length from Deptford to Crossness. At Beckton and Crossness, the sewage was stored in huge reservoirs, from which it was released into the Thames at high tide. 

The Thames Embankments

Commencement of the Thames Embankment: Driving the first pile in front of the Duke of Buccleuch's mansion.
View full size imageCommencing work on the Thames Embankment. © NMM

The Embankments on either side of the Thames were another benefit of Bazalgette's scheme. The idea of building embankments to reclaim marshy land along the riverbank had been debated for centuries, but little was done before Bazalgette. 


Landing materials to build the Embankment.
View full size imageLanding materials to build the Embankment. © NMM
His embankments concealed sections of his intercepting sewers, and avoided the huge cost and inconvenience of digging up central London streets. They reclaimed nearly 10 hectares (22 acres) of mud, and also concealed a section of the Metropolitan Railway, the world's first underground railway line.

Bazalgette's legacy

Northern Outfall Sewer: east of Stratford.
View full size imageThe Northern Outfall Sewer east of Stratford. © NMM
The whole scheme took seven years to complete. Bazlgette's achievement was amazing even by modern standards. When completed in 1865, London had 2100 km (1300 miles) of sewers, including 130 km (82 miles) of the main intercepting sewers.  Almost a century and a half later, London still relies on Bazalgette's sewers. 


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