A call for New Zealanders to do the checks before hydrating or swimming this summer

Water New Zealand says it's important to boil or treat tank water, as it can easily be contaminated by vermin or bird droppings.

It's urging people to check for boil water notices around public or council water supplies, as it means E. coli has been found, usually from faecal contamination.

There is also a similar risk when swimming in rivers, lakes, or at the beach, especially in the two to three days following heavy rainfall.