Drug Foundation spokesperson Hayden Eastmond-Mein said their drug checkers at the Gisborne festival are at capacity.
Eastmond-Mein said there is a limited number of spectrometer testing devices available which means they need to be shared around other New Year's festivals.
Last year they tested roughly 1000 samples at the festival and they expect this year to be just as busy, with more than 26,000 attendees expected.
"We've been really busy at [Rhythm and Vines] which is awesome, this is our first day testing, we're testing right throughout the festival.
"Our people are seeing a lot of people through and they are slammed which is what we want to see," he said.
He said their team of 12 will be at the three-day festival until 5pm each day.
Thousands of pitch tents despite record rain
Over 17,000 campers are checked in and ready for Rhythm and Vines' first day despite record rainfall.
Gisborne saw a month's worth of rain and high winds on Boxing Day, the region's wettest day since records began in 1937.
Rhythm and Vines' head of marketing, Kyle Bell, said the festival asked campers to delay their arrival until after 12pm yesterday to allow the ground to dry up.
"A couple of days out the ground was a little bit soggy we just wanted to make sure people took their time coming in."
He said luckily the high winds they have been experiencing helped to dry the ground, leaving festival-goers with a solid patch to pitch their tents later that day.
Bell said the weather is looking promising for the expected 25,000 people who have purchased tickets to the three-day festival.
