Grey District council has issued a ban on all handheld watering devices and sprinklers.

Workers are frantically trying to fix a broken water main in Greymouth to make sure the West Coast town has water for Christmas Day.

A large leak on a water main in the town caused the town's reservoir to empty.

Grey District Council utilities team leader Kurtis​ Perrin-Smith said the council identified a leak on the main water line into Greymouth on Monday afternoon.

STUFF Greymouth residents are being asked to conserve water after a break in a water main caused the reservoir to empty.

"The reservoir storage for the main Greymouth area has dropped effectively to zero so we have no storage left in the Greymouth area."

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He hoped to have the problem fixed before midnight on Christmas morning.

Residents were asked to conserve water until further notice, with a ban on all handheld watering devices and sprinklers. This would remain on Christmas Day and Boxing Day at the least.

"Standard use for cooking, cleaning and sanitary purposes is OK, but any unnecessary use like washing the car, watering the gardens, we're asking people to delay that until we get our storage back."

Perrin-Smith said in his 15 years at the council, this kind of event had never happened before.

The problem affected Greymouth, surrounding towns and settlements.