As if they haven't suffered enough, Cantabrians toiling to clean up after Saturday's quake now face a potential shortage of Canterbury Draught beer.

And the rest of the country also faces running out of a number of well-known brands, including Guinness, Beck's and the Macs Craft range.

Lion Nathan's Christchurch brewery - which suffered heavy damage in the 7.1 magnitude quake - is closed, and likely to stay that way until the end of the week. It is the sole producer of the four popular labels.

Lion Nathan spokeswoman Judy Walters said it was not clear whether supplies of the brands could be maintained during the week, although reserve stock around the country could be shifted to meet demand.

She said many of the company's other brands were manufactured at multiple sites around the country.

The Christchurch factory is being assessed by structural engineers.

"At this stage we're saying that it's unlikely that we'll be doing any production or deliveries [from Christchurch] this week ... [but] I don't think people will be going thirsty."