Officials expect further testing of water from the Waikato River will help them start to understand the cause of elevated arsenic levels

Auckland's Watercare and Hamilton City Council have reported slightly elevated arsenic levels in recent samples of treated water.

The National Public Health service says drinking the water for a short period is unlikely to impact people's health - it is safe to drink.

Waikato Regional Council Science Manager Mike Scarsbrook says they're waiting on results from latest testing.

He says those results are due this afternoon.