Havelock North's campylobacter outbreak has so far cost Hawke's Bay District Health Board an estimated $380,000.
It's the first time the DHB has given an insight into the financial hit it has taken from the water disaster that left more than 5000 people with the gastro illness last month.
More than half of the cost, $216,000, was attributed to staff sickness.
Hawke's Bay Regional Hospital's intensive care unit was saddled with predicted extra costs of $66,000.
The DHB has done four telephone surveys, and is doing a further study to look into the extent of reactive arthritis in the community - the more common of the two post-campylobacter infections. These surveys are costing an estimated $24,000.
"Gastro clinical supplies" have cost the DHB $23,000 during the outbreak, and "dehydration management resources", such as drips, cost an estimated $18,000.
The cost estimates were released at yesterday's DHB meeting in Hastings.
In a statement, chief executive Kevin Snee said although the estimates were an "extra cost burden" to the DHB, "they were not at a level that had been disruptive to the organisation".
The DHB's latest annual report shows an operating surplus of $3.1m in 2014/15, and a $3.2m surplus the year before.
Hastings District Council, which manages the water supply, could not provide cost information. A spokesperson said the council was still assembling information on the total bill it was facing.
Earlier this month Work and Income said almost $17,000 in Civil Defence payments and emergency grants had been paid out to cover food, water, medical bills and loss of income.
A government inquiry into the water disaster, led by retired judge Lyn Stevens, is due to report back by June next year.