A Canterbury swimming complex is remaining open after cryptosporidium cases were linked to the pool

There's been 18 cases of the gut parasite in Selwyn confirmed in the past week, all stemming from Rolleston's Selwyn Aquatic Centre.

The district council's been working closely with health authorities since being advised people were ill last month.

Water testing has increased - as well as cleaning and chlorine doses.

Medical Officer of Health, Doctor Cheryl Brunton says the pool complies with all relevant standards.