Council officers undertook precautionary testing on water bores during the weekend after the contamination in Havelock North.
Director Infrastructure, Jon Kingsford, says the precautionary testing was done over and above routine testing.
"Our water is tested in accordance with the Ministry of Health Drinking Water Standards, which means water supplies are tested anywhere between 2-7 times a week, but routinely 2-3 times a week," Mr Kingsford says.
"All bores are tested once a month as extensive long term testing has allowed them to be granted full secure bore status."
"Our frequency of sampling is set at around 200 per cent of what is required under the Drinking Water Standards."
Napier Mayor, Bill Dalton acknowledges the seriousness of the issue and says his sympathy goes out to everyone affected.
"Havelock North is an important part of Hawke's Bay. We have a lot of people who live in Havelock North and work in Napier or vice versa, so we are all feeling the impact too.
"I have personally offered our assistance to Hastings Mayor Lawrence Yule. We are here and willing to help with resources and personnel whenever it is required. It is times like this that we have to band together and help each other get through."
He assured residents and visitors that Napier is "open for business".