An inquiry looking into the Havelock North water contamination crisis is set to begin hearing from key witnesses.
More than 5000 people became ill and at least 20 were hospitalised after the town's water supply was contaminated with campylobacter in August last year.
An inquiry looking into the cause of the outbreak and the response by authorities was delayed last year and is set to continue in the Hastings District Court on Monday.
Water services manager Brett Chapman and water supply manager Dylan Stuijt, both from Hastings District Council, as well as molecular biologist Dr Brent Gilpin are among five who will give evidence on the first day.
Twenty-five witnesses will be called over the three-week hearing, led by retired Court of Appeal judge Lynton Stevens. Most of those giving evidence work for either the district or regional councils.
The inquiry will report to Attorney-General Chris Finlayson in March.
Havelock North's drinking water is now being drawn from the Hasting's supply.