Heating element used in water require very high safety standard.

(1) Storage water heater heating elements.

(2) Electric showers (UK/Germany) or instant water heaters (USA).

(3) Solar water heaters (required in solar water heaters when weather is not so good).
 
Tube material to be optional: copper, stainless steel, Incoloy etc.
Power, flange, shape, serface treatment to be tailor-made or agreed.

You can contact Mr. Charlie WU for fast reply.