A three-day planning inquiry hearing has begun over proposals to construct Sewage Treatment Works (STW) at a site in Peel.
Manx Utilities wants to get the green light to erect the plant at Glenfaba House by the Raggatt, but has been met with opposition from Patrick Commissioners.
Discussion will take place on issues ranging from the environmental effects to the visual impact of the works, as well as whether another site could be considered.
Representatives from both sides will put forward their arguments before planning inspector Brian Sims makes his closing recommendations on Thursday.
Chairman of Patrick Commissioners, John Anderson, is also a neighbouring farmer to the land at Glenfaba House.