Nearly $1.5 million has been spent by the Hawke's Bay Regional Council on the Havelock North water contamination.
The contamination of the Hastings suburb's water supply in August led to more than 5000 residents becoming ill with gastroenteritis, and has been linked with three deaths.
After a two-week hearing in February, the inquiry into the contamination is now deliberating, with its reporting date of March 31 expected to be pushed back.
A report to be presented at tomorrow's regional council meeting shows $1,484,800 has been spent on the inquiry and its own investigation.
The paper, prepared by group manager resource management Iain Maxwell, states $1,040,549 was spent up to March 16 on the inquiry, including $283,629 on internal time and $756,910 on external costs.
The majority of the external costs - $612,830 - was spent on legal fees with Mai Chen of Chen Palmer representing the council during the inquiry.
The council also spent $444,251 on its own investigation to determine whether the contamination was in part or wholly the result of resource consent conditions not being met.
The outcome of this investigation saw the regional council drop its two charges against the Hastings District Council for unlawful water takes.
The district council had conceded the breach of resource consent conditions and agreed to not contest two infringement notices, resulting in two fines of $500 apiece.
The amount spent on the investigation included $211,977 in external costs - with $100,000 spent on external laboratory testing, and $20,000 on legal advice from Jonathan Krebbs for the investigation for prosecution.
Mr Maxwell wrote the past period had seen further significant costs "given the nearly two weeks of hearing time".
"We have actively managed the attending Counsel so that a junior Counsel was in
attendance during sessions that were not directly related to HBRC," he stated.
"Nonetheless there remains a significant cost, not all of which has been fully invoiced yet."
While there would be further costs associated with the second stage of the inquiry, it was thought these would be "significantly less" than for stage one.
The council had "tentatively" engaged a locally based planning consultancy to assist with the second stage.
"We anticipate that the costs associated with stage two will be substantially less than stage one as we see this process being led by the planners," he stated.
Mr Maxwell wrote they understood the inquiry panel would, or had already, sought permission from the Government to extend the reporting dates to allow stage one to be reported in May, and stage two toward the end of the year.