South West Water must now build a secondary treatment plant
Plans for a sewage plant discharging into the sea off Cornwall have had to be upgraded by South West Water (SWW).
SWW wanted to build a primary treatment works for sewage from the villages of Bossiney and Tintagel.
But the county council rejected its application after people in the area called for a secondary treatment works and a public inquiry was held.
The planning inspector has now agreed secondary treatment is needed and SWW will have to submit new plans.
Primary treatment removes solid waste material, with secondary treatment cleaning up the waste using filters and bacteria.
Objectors, led by local group Tintagel Against Inferior Sewage Treatment (TAIST), said the villages were so close together that their discharges should be considered equivalent to those of a single larger settlement.
That meant they should have a higher level of treatment than South West Water proposed.
The inspector found that Tintagel and Bossiney's combined population of more than 2,000 exceeded the threshold at which a higher level of treatment is required for coastal discharges.
Surfers Against Sewage (SAS), which supported local people against the initial plans, welcomed the inspector's decision.
SAS campaign director Richard Hardy said: "It seemed a no-brainer really, but we needed the legendary campaigning skills of King Arthur and the magic of Merlin to see this proposal rejected.
"The biggest thumbs up though has to go to TAIST, who have done a fantastic job in showing just what a local grassroots community group can do."
Chris Mills, SWW commmunications director, said the firm would now be looking at sites for a secondary treatment works and a new pumping station.
He said: "Our goal all along has been to provide residents and visitors with a modern sewage treatment system that represents the best value for money for our customers.
"That remains our goal."