Normally Kaikohe takes most of its water from Wairoro Stream just north of town, with water pumped from a bore on Monument Hill as a back-up.
However, logging near the stream has increased silt levels to the point where sediment keeps blocking filters at the council's Taraire Hills Water Treatment Plant, reducing the volume of water that can be treated.
To compensate, the Far North District Council has increased the amount of water it takes from the bore, which taps into the same aquifer that feeds nearby Waikotihe spring.
A relatively dry winter means the water level in the aquifer, 54m below ground level, is lower than normal.
If it drops to 58m Waikotihe spring is expected to dry up and the council's resource consent will ban it from taking any more water from the bore.
The council expects the water level to drop another 4m over summer.
The chairman of Waikotihe Trust, Wi Pou, said he didn't want to see a repeat of 2012-13 when the spring ran dry because the council was taking more than it should.
The water was better managed now but silting of Wairoro Stream had placed extra demand on the aquifer.
He urged all Kaikohe residents connected to the council supply to cut back their water use to help preserve the spring.
''This spring is a taonga for us. It's a key part of our identity and the life force of the hapū.
"To lose it would be devastating for us, but that would also mean Kaikohe's whole water supply is in jeopardy," Pou said.
The hapū's water conservation message was also directed at residents beyond Kaikohe.
With a drier than normal summer predicted, many rural Kaikohe and South Hokianga residents would buy water to replenish their rain water tanks.
The closest filling point for bulk water trucks was Kaikohe, so that also put pressure on the town water supply.
Council infrastructure manager Andy Finch said extra membrane filters would be installed at the Taraire Hills plant to increase production, but sourcing and fitting the equipment could take as long as five months.
Recent rains wouldn't help and could even make the problem worse, he said.
"The aquifer takes months to recharge from rainfall. At the same time, rain falling in the Wairoro catchment will likely increase sediment downstream, putting an extra load on our filters.''
Fortunately logging work in the catchment was winding down so water quality in the stream was expected to improve over the coming year.
Finch said council staff would contact high water users in Kaikohe to urge them to reduce consumption.
If water use did not fall in the next few weeks, restrictions would be imposed and enforced, he said.
The Northland Regional Council, which issues resource consents for logging, has been contacted for comment.
Waikotihe Trust is the kaitiaki (guardian) of the spring and surrounding land.
For tips on saving water, go to bewaterwise.org.nz. To tell the council about water leaks or breaches to water restrictions phone 0800 920 029.
