While an influx of summer visitors put extra strain on the township’s water supply, the "excessive" usage has stumped the Westland District Council.
General manager district assets Erle Bencich said the Haast water treatment plant was able to generate 140,000litres a day, and the reservoir had a 400,000litre capacity.
However, cartage contractors had to be deployed to transport water from Fox Glacier via tankers to supplement the Haast reservoir from December 29 to January 16.
"Although tourist numbers were high over this period, weather conditions were not particularly dry, so the amount of production is viewed as excessive," Mr Bencich said.
"Leak detection and heavy usage inspections were undertaken over the holiday period, culminating in an advised property-by-property investigation last week in Haast. The results have remained inconclusive as coincidentally water usage returned to more normal levels at this time."
A conserve water notice was put in place on New Year’s Eve, banning all outdoor use.
Mr Bencich said this week water production and reservoir storage levels had remained stable since last Friday, and the restrictions had now been lifted.
However, staff were still keeping an eye on consumption levels.
About 210 residents are connected to the town supply.
"Council staff and contractors will continue to closely monitor water production from the plant and usage in this network, which could also include metering of different sectors to pinpoint high water loss or excessive usage."
Haast township averages about 2814mm of rain a year — more than four times Canterbury’s annual rainfall, which averages 648mm.
