People will gather at 3.45 at Ham Lands, head past the common and finish at the YMCA Hawker Centre in North Kingston, which is where Thames Water is holding a consultation on the plans between 2pm and 8pm today.
Thames Water says the project is designed to protect water security for future generations and will enable the company to abstract more water from the River Thames during periods of drought, supported by water recycling.
The proposal would see water extracted from Teddington Weir and transported through an existing underground tunnel to the Lee Valley.
The water would then be replaced by treated effluent from Mogden Sewage Treatment works in Isleworth.
But those against the plan say wildlife and biodiversity would be decimated.
A public consultation is open until the 11th of December and is asking for feedback on the potential sites for the new structures, pipelines and shafts that Thames Water think would be needed for the project.