Scores of sites across the capital are expected to be on the list.
The company has issued a leaflet called Spreading the word on the need for tunnels.
Thames Water's head of London Tideway Tunnels Phil Stride said: "Our key task on the project is to ensure that the UK complies with the Urban Wastewater Treatment Directive."
Hammersmith & Fulham councillor Greg Smith, who has responsibility for parks and open spaces, said: "Residents want to know which sites Thames Water is proposing to blight during the construction phase now. Maybe they are being secretive because the apparent environmental and health benefits simply do not justify the colossal financial cost and massive disruption to residents’ lives.
"We have some of the best open spaces in London - including three Green Flag parks - and this council will fight tooth and nail to protect them."
Thames Water say the £2.2bn, 36km long sewage storage tank, which would take at least eight years to build, is needed to prevent sewage flowing into the Thames.