It is alleged that low levels of the parasite cryptosporidium were discovered in the treated drinking water at the Alderney water treatment works in May 2013.
The parasite can cause gastrointestinal illness, particularly in young children.
The Drinking Water Inspectorate (DWI) confirmed there is due to be a hearing at Bournemouth Magistrates’ Court on 25 March but could not provide any further details ahead of the case.
Sembcorp Bournemouth Water managing director Roger Harrington said: “In view of the impending court case, I am unable at this stage to comment in detail.
“However, I can confirm that since May 2013, when the matter under investigation occurred, we have implemented a range of enhanced protection measures.
“These include a new £3.5 million ultraviolet plant at our Alderney water treatment works.
“The use of ultraviolet will complement the current chlorine-based disinfection process, improve disinfection and reduce chemical usage.
“Ultraviolet disinfection will completely eliminate any risk from cryptosporidium.”