The people of Havelock North are entitled to know why they got sick from their drinking water. The Government Inquiry into Havelock North Drinking Water should give them their answer. I have extra questions over how well the whole regulatory system was designed and operated. The same system is supposed to protect us all from this kind of incident but it obviously didn't in this case. This page collects the better posts I have put up and useful links.
Government Inquiry into Havelock North Drinking Water - all the main documents are posted here. If you know how to read them they are more enlightening than anything I can say.
Science Media Centre backgrounder on aquifers, groundwater and contamination. Terrific explanations of the science.
Will HBRC Score an Own Goal? - contains a picture of the working relationships between HBRC and HDC. It is important to understand when HRBC is the regulator and when it has an operational role (also subject to audit or scrutiny)