A Fire and Emergency New Zealand (Fenz) spokesman said the fire was discovered by a council staff member, who was alerted by an alarm activation at 1.48am.
Crews from Oamaru arrived at the site at the corner of Richmond and Ferry Rds, north of Oamaru, just after 2am and called for a tanker from Weston to assist.
The fire was in found in a small shed and damaged some electronics, the spokesman said.
A fire investigator is at the scene this morning to determine the cause of the fire.
Crews left the scene at 3.30am and there were no injuries to report.
In a Facebook post, the council said the water supply had been turned off and residents were asked to conserve water until further notice.
Council staff met this morning to discuss ways to resolve the issue and would provide an update this afternoon on its social media channels.
About 800 customers were affected by the outage.
