The Green Party wants to introduce a bill to ensure the Water Services Authority regularly publishes data on drinking water quality.

The party said this would ensure people could easily check the safety of their public drinking water supply.

The Water Services (Increasing Transparency of Quality of Drinking Water and Drinking Water Sources) Amendment Bill, which the Greens released on Friday, would require Taumata Arowai to publish and update drinking water quality data online, introduce consistent standards for how the information is reported, and publish drinking water safety plans.

In Christchurch on Friday, co-leader Marama Davidson said up to 100,000 people get sick each year from polluted drinking water.

"Nitrate pollution in our rivers is getting worse, and it's costing ratepayers in Ashburton, Selwyn, Waimate and Gore at least $17 million combined.

"Five schools in Otago, Canterbury, and Waikato have had to upgrade their water systems just so their children can have a safe drink of water at playtime."

Davidson said while some councils (such as Hastings, Gore, Selwyn, Waimate and Ashburton) regularly published their drinking water data online, many did not.

"This turns a glass of water into a postcode lottery. The Green Party will make sure water quality reporting is transparent, consistent, and accessible online."

The bill would require the publication of water quality monitoring information at the source and tap "as soon as practicable" after it was received from a supplier.

It would not change any requirements for which suppliers must report to Taumata Arowai.