Hamilton City Council is keeping a close eye on the Waikato River following a water main and wastewater pipe break in Lake Taupō on Tuesday afternoon.
The water main broke at 2pm on Tuesday afternoon causing a large washout on the lakefront.
About an hour later the footpath collapsed and took out a wastewater pipe, resulting in about 800,000 litres of wastewater entering the lake.
Hamilton City Council compliance manager for City Water Trent Fowles said increase monitoring is taking place on the river from which Hamilton draws all its water.
"Hamilton City Council does not anticipate any disruption to the supply," Mr Fowles said.
"However, we have increased monitoring of the raw water quality to see if there is any increase in organic matter, and process would be altered as required to treat any increase."
"We are also ensuring the reservoirs are holding more water than normal."
"As has been previously identified, there would be significant dilution between Taupō and Hamilton. We will continue to monitor the situation and will alert the community immediately if there is an impact on the quality of the city's drinking water."
In Taupō, residents are being urged to minimise their water use for the next three to five days.
Pumps were brought in yesterday, and sandbags have been put in the manhole and the pipe, as a further preventative measure.
Drinking water was not affected, while water sampling will be taken twice daily for at least the next three days to determine E. coli levels in the lake.
Taupo District council is working with Waikato Regional Council and iwi to begin the clean-up although it was unclear how long it would take.