According to Official Guinness Records,
The longest line of detergent capsules/tablets is 8,177, achieved by Unilever PLC (UK) in Surrey, UK on 25 January 2018. The line measured 456.77 m and was was constructed by a group of 33 participants from Unilever's engineering team.
For a complete list of 2018 records, please visit 2018 Guinness Records in United Kingdom.