The super sewer was granted planning approval on Friday by the environment and communities secretaries, despite opposition from Hammersmith and Fulham Council and Southwark Council.
Both local authorities have told Utility Week that they are now taking legal advice on whether they should mount a legal challenge against the decision.
The authorities have six weeks from the day of consent to formally file their challenges.
Hammersmith and Fulham Council opposed plans for a tunnelling site to be situated by Carnwath Road because it would cause “avoidable misery” and “24/7 noise, dust and air pollution” for residents.
Meanwhile, Southwark Council opposed the plans for the Thames Tideway Tunnel to use Chamber’s Wharf as a construction site.
Leader of Southwark Council, Peter John, said: “This is a ludicrous and evil decision by the Secretaries of State as the Planning Inspectorate clearly found that Chamber’s Wharf was not a suitable drive site for this super sewer.”
He added: “We will continue to fight this decision and look at all our options including a Judicial Review, and ensure Thames Water is held to account along every step of the planning process to get the best possible outcome for our residents.”
Thames Tideway Tunnel said they would not comment on speculation.