We had also a leak in our Amundsen and went to our dealer. Finally the cause was not the piping but only the water tap / shower head. There was a small rinse from there to the piping. Just try first if the shower had is thoroughly fixt.
Hope it helps,
Miguel
Victron Smart Solar, Shunt, Orion Booster; Votronic Standby Charger; BOS LE 300 LiFePO4; Ramto Felgen mit 17’’ Allwetter Conti; Android Radio und Gladen One165, X1 Pro Rückspiegel; AMG AlarmTab; Night Breaker LED