Chief Executive Wayne Jack said rather than reopening the tank right away, it was opting to bring in an expert commercial dive team to inspect, clean and vacuum both tanks of the reservoir.
This highly specialised work, undertaken by an experienced dive squad who work with councils and water companies around New Zealand, was due to start on Thursday, and conclude late on Friday.
Daily testing for e.coli, and chlorination would continue until the reservoir had been fully cleaned and was ready to be reintegrated into the Napier city water network.
Manager Asset Strategy Chris Dolley said Council has also formulated a programme of work that should mitigate any future opportunities for e.coli to present in its reservoir.
"We haven't yet been able to isolate the exact cause of the contamination but we're continuing to investigate the cause. We'll also be looking at what improvements can be made to decrease the chances of anything like this happening again," he said.
The proposed works programme included upgrading sampling points in the water network and increasing the frequency of cleaning.
Level two water restrictions WILL remain in place for now, as to clean both tanks at the affected reservoir will mean they are both offline for short periods of time.
"Although rain is forecast this week, we're also looking at the mid-range forecast and seeing another spell of dry and hot weather in the near future," Mr Dolley said.
"Understandably, this typically means that residents get the hoses and sprinklers out. So we are reminding our community to keep up their great work they've been doing so far to lighten the load on our reservoirs and allow them to stabilise.
"We'll be keeping the public informed of our progress along the way and of when the restrictions are likely to be lifted."
Today, a multi-channel media campaign began sharing "top tap tips" with the Napier public and informing them of the guidelines around restrictions.
Already, social media has seen a "direct and positive impact" on reservoir levels, Mr Dolley said.
"It has been a very effective channel over the long weekend but we're looking to more traditional methods, too, to reach a larger sector of our community. We also want to take this opportunity to thank the fantastic people of Napier for their positive response so far."
For those unable to tolerate the chlorinated water supply, four chlorine-free taps remain in place at Anderson Park - a location in which Napier City Council was able to access a steady unchlorinated supply from a separate source to the Enfield reservoir.
The public is welcome to use the York Ave taps, set up next to the light blue Girl Guide hall in Anderson Park. Signage has also been installed to assist with way-finding.