A group mounting a legal challenge against Chinese water bottlers in Christchurch over concerns Environment Canterbury cut corners when it gave consent.

Cloud Ocean Water has consent to drill a 170 metre bore, but still needs permission to take water from it.

The company inherited a consent to obtain 1.6 billion litres of water a year for export to China, which could see potential earnings of $4.3 billion annually.

It is allowed to take 50 litres per second from a shallower bore.

Aotearoa Water Action has lodged an application for a judicial review around the consents.

Spokesman Peter Richardson told Chris Lynch ECAN has a lot to answer for.

"Well, we don't believe they followed due process in granting the existing consents they granted to take water from the shallow bores. We don't have any confidence."

Richardson believes ECAN rubber stamped the consents without considering the risks, especially the amount of water the company can take.

"We don't know whether that's sustainable, we don't believe it is, we don't think it's safe."

Christchurch City Councillor Vicki Buck is seeking assurances that the new bore won't affect the city's drinking supply.