Yes, the tank is considered a pressure vessel, it consists of a steel tank with a rubber bladder inside that contain the water. High pressure air surrounds the bladder at a operating pressure of 7-9 Bar. (the tank is rated 10 Bar) . I have attached the two documents that normally works for any inspection authority. I have also added the documents and the EU declaration in the folder \ Firefly_pump_and_water_system\ Pressure Tank Documents. https://fireflyab-my.sharepoint.com/:f:/g/personal/adam_sandstrom_firefly_se/Es7Qq6vOJexAtLX4yp8G2_sB0OpV5LgwzIdAmEyxDmuKQw. Password: FF15209. If you will need additional documents, please let me know and I will try to talk to the manufacturer and get it for you. Hopefully, they are well aware of the EU pressure vessel directive and if a product conforms to that, it will also be good enough for them.