Twelve hours' unrelenting rain across the Waikato today has prompted Hamilton City Council to ask the city’s residents to be cautious and patient.

Hamilton was saturated by more than 100mm of torrential rain from 6 this morning until 6 this evening.

The deluge has put significant pressure on Hamilton’s drains and sewerage system.

Andrew Parsons, Council’s City Waters Manager says obviously that volume of rain has to go somewhere, popping manhole lids, flooding roads and gutters, and blocking some drains.

Mr Parsons says it is unsafe and impractical for staff to clean up through the night, and residents are asked to be patient.

He says urgent and serious jobs will be done tonight, but most of the clean-up will start tomorrow.