The consultation on the UK’s biggest sewer began this week.

The Planning Inspectorate examination will look into the £4.2bn, 15-mile, 200ft deep Thames Tideway Tunnel, designed to will capture 39m tonnes of untreated sewage that is currently flushed into the Thames every year.

The Planning Inspectorate held a preliminary meeting for the application for development consent on September 12 and 13, which marks the start of the six-month investigation.

A Planning Inspectorate spokesman said: “The meeting is not designed to discuss the merits of the supplication itself.

“After that the Planning Inspectorate will issue an examination timetable which will have all the dates interested parties can respond to.”

The Planning Inspectorate then has three months to write reports, which will be submitted to the Secretary of State, who then has three months to decide.

A planning application was a notice of acceptance earlier this year for Thames Water to build a sewage interception site on the south eastern perimeter of Barn Elms playing fields.

Work includes construction of underground structures to connect the combined sewer overflow to a shaft 34m deep, 6m in diameter.

While the main work will be underground, there will be a permanent kiosk and ventilation structure above ground.

Construction by the playing fields is due to start in 2017 and be complete by 2019.

In November 2011, campaign group Stop the Shaft (StS), councillors and MPs, won a battle against Thames Water to build a main tunnel drive site by the playing fields, which would have been a much bigger construction lasting up to seven years.