Dubbo Regional Council issuing a boil water alert Thursday that could last up to seven days. Residents quickly rushed out to buy water, leaving supermarket shelves bare.

Patrick O'Neill, manager at Ashcroft's IGA in south Dubbo said there was more water on the way and there was no need to rush.

He said the store has a truckload of water coming from Sydney which would more than make up for demand later this week.

"We were sold out by about 8.30-9am this morning and the local guys had another delivery here by 9.30am for us," Mr O'Neill said.

"We'll have a semi coming [on Friday] and we should have at least another four pallets of water [later on Thursday]. I don't think there's an issue to panic, it will be really hard to buy water today because everyone wants it... but they'll have it tomorrow and the next day anyway."

Josh Mackintosh, operations manger from Inland Distributors in Dubbo said they know demand has increased and were working on getting more water out to local shops.

"Where we are [with stock], we are alright at the moment. With the influx that we've had [we said] 'okay, it's going to go a lot quicker than predicted...'," he said.

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One shopper at Dubbo Aldi, Gary Cowper said he prepared early.

"There's no water, it's crazy, it's like the toilet paper again," he said.

"We've actually got a bit of water already at home so we should be alright for a week."

"We were prepared ahead of it."

Dubbo Regional Council mayor Mathew Dickerson said council staff were working hard on the issue.

"I think people understand generally that there are sometimes things that are out of our control, it's pretty hard to predict some of the rain events we've had over the last six months especially consider it was only two-and-a-half years ago that we were still in drought," he said.

"This is something that - we need to be mindful of the fact we've got this water event, this rain event and we've got to deal with it and cope with it and make sure that we don't let this happen again."