A public inquiry into plans for a sewage treatment plant in north Cornwall is due to open on Tuesday.
Objectors claim SWW proposals are not good enough
South West Water's (SWW) application for a primary treatment works in the village of Bossiney was turned down by the county council.
SWW already has permission for a fine screening unit in nearby Tintagel, but the county council and people in the area want a secondary treatment works.
SWW says it is committed to delivering environmental improvements.
When the county council turned down the Bossiney application, SWW appealed and the decision has now been "called in" by the Secretary of State for the Environment.
During the inquiry, a government inspector will hear evidence from all sides, including local protest group Tintagel Against Inferior Sewage Treatment.
SWW said it was committed to delivering environmental improvements in the area, but added that until one or other of the treatment works was completed, raw sewage was being discharged.