Residents in parts of south-east London say they fear their neighbourhood could be ruined due to the construction of Thames Water's £3.6bn "super-sewer".
The 20-mile (32km) Thames Tunnel would run from west to east, broadly following the river, collecting sewage discharge triggered by rainfall.
But people in Rotherhithe said the work would cause huge disruption and destroy the little green space they have.
Thames Water said final decisions on work sites have not been made.
One of the proposed work sites is at King Stairs Gardens.
Local resident Donna Spedding said: "We were devastated when we heard about the proposals.
"We find it outrageous that Thames Water can even consider ripping the green heart out of this community."
Sister Cecily Dunn, from the local Bosco Centre, a nursery and community centre, said: "It is going ahead and I think it is absolutely wrong.
"It is the only green space we have alongside the river."
A 14-week public consultation on the Thames Tunnel began on 13 September.
Philip Stride from Thames Water, said: "I do understand the concerns.
"All I can say is, give us your feedback, we are very keen to hear your feedback, and we will actively follow that feedback up."
The tunnel will be at a depth of about 246ft (75m) and will emerge to the east of Tower Bridge at Limehouse before going one of three ways:
- North-east to connect to the Lee Tunnel at Abbey Mills in Stratford - the shortest of the proposed routes;
- East following the river and crossing the Greenwich peninsular up to Beckton Sewage Works in Newham;
- South-east, straight to Greenwich and then on to Beckton.