A public inquiry into proposed sewage treatment works in north Cornwall is to cost the county council at least £7,000 more than was previously thought.
South West Water appealed against a decision to refuse an application for the works at Bossiney, near Tintagel.
The matter was then referred to a four-day public inquiry that began in February but was adjourned until April.
The council's cost of representation at the inquiry was estimated at £17,000. It has been revised upwards to £24,000.
In 2004, South West water drew up plans for a treatment works at Back Lane in Bossiney. They said it was the best option as other sites would cause more environmental damage.
But after strong local opposition - and fears about the impact on tourism - the county council's planning committee refused the application.
The inquiry, which began on 28 February, had to be adjourned until 19 April because it could not be finished in the allotted time.
More than 100 people protested against plans for a sewage treatment works in Cornwall when councillors visited a proposed plant site.
The site is listed in proposals by South West Water (SWW) for a new treatment works near Boscastle.
Protesters said the plans would result in three plants within a 3 mile (4.8km) stretch of land because of treatment plans for other nearby areas.
SWW said the site was right and the works were essential.
The company is trying to improve sewage treatment for Boscastle, Bossiney and Tintagel.
It said there would a mix of preliminary, primary and secondary treatment at the three sites, but some people want a complete rethink.
Graham King from Boscastle's sewage liaison group said: "We feel that having three separate sewage treatment plants within three miles of coastline is too much.
"We feel that SWW haven't properly examined the possibilities of having one site, one outfall for all three areas, all three villages."
The plans for the secondary plant at Hillsborough Farm near Boscastle have also run into opposition from the National Trust, which owns the land.
Ian Kemp from the Trust said: "Whilst we don't want to be obstructive to the desire to get a treatment plant scheme somewhere in Boscastle, we're not convinced that this is the right site and this is the right scheme."
Keith Field of SWW said: "Sewage treatment works are an essential part of living but nobody wants them near to their community, so we've had this extensive search for a site.
"We believe we've found a suitable site for Boscastle at Hillsborough."
He added that some of the "silent majority" of supporters of the scheme also had the chance to meet with councillors at the site on Wednesday.
Planners for Cornwall County Council will make the decision as to whether the Boscastle plans will go ahead.
A public inquiry is to be held into the plans for Bossiney and Tintagel.