The Far North District Council is trucking in water from Auckland to supply Ngawha Prison in Kaikohe.
It comes as the lowest water flows in 50 years have driven drought conditions across the region.
Normally the prison takes around 16 percent of Kaikohe's water supply, although its water access has been restricted since 5 February, and the new supply will ease the drought's strain.
The council said with rain levels predicted to stay low for several more weeks, it was trying to find supplementary supplies for Kaikohe.
It said the result of investigations would be announced shortly.
Kaikohe residents were already limited to using water only for drinking, cooking, and washing.
Since 5 February, Kaikohe was able to reduce its water consumption by more than 19 percent.
However, that was not a signal to relax.
"Water levels in the Wairoro Stream are still falling and we expect this trend to continue until we receive significant rainfall," district council infrastructure manager Andy Finch said.