River Westbourne

The Westbourne or Kilburn, also known as the Ranelagh Sewer, is a culverted small River Thames tributary in London, rising in Hampstead and Brondesbury Park and which as a drain unites and flows southward through Kilburn and Bayswater (west end of Paddington) to skirt underneath the east of Hyde Park's Serpentine lake then through central Chelsea under Sloane Square.

Since the latter 19th century, the population of its catchment has risen further but to reduce the toll it places on the Beckton Sewage Treatment Works and related bills[clarification needed] its narrow basin has been assisted by private soakaways, and public surface water drains.

The Serpentine was formed in 1730 by building a dam across the Westbourne at the instigation of Queen Caroline, wife of George II, to beautify the royal park.

[6] When west Belgravia, east Chelsea and Paddington were developed, it was becoming obvious the river would have to remain a combined or foul sewer, with a certain storm element until such time as surface water drains (if ever) were built upstream.

As some of its foul content overwhelms the system with further inflows from the west, an improvement, the Thames Tideway Scheme tunnel will enable that sewer to continue to cope.

[6] The finest and most intelligible map of the whole course of the Westbourne, superimposed over the Victorian street plan, is found in an article by J. G. Waller, published in the Transactions of the London and Middlesex Archaeological Society, vol VI (1882) pp 272–279.

[9] Waller's map shows that the stream never ran further west than the easternmost extremity of Westbourne Grove, Notting Hill (an east–west road ending at Queensway where the course lay).