According to Official Guinness Records,
The most hits of a person with water balloons in one minute is 42, and was achieved by Ashrita Furman and Bipin Larkin (both USA) in Jamaica, New York, USA, on 21 September 2016.To achieve this record, Bipin Larkin threw and hit Ashrita Furman with water balloons from a distance of 10 metres.
For a complete list of 2016 records, please visit 2016 Guinness Records in United States.