What size water hosing is used? Andrzej October 27, 2017 09:32 Updated Follow We use 8mm internal diameter hosing (around 10mm external) for all of our water lines. Related articles Do I have to protect the HOTTAP from the elements? Why are your prices higher than competitors? Where is Joolca based? Setting up your HOTTAP How long is the warranty period for? Comments 0 comments Please sign in to leave a comment.