Different system here with more possibilities for debris papadave , I often get clogged lines from debris building up in the screen of feeding hoses. Cleared the washing machine screen clog last night......
I'll second that. The lime, calcium or other deposits settle to the bottom of the tank and can eventually surround the lower heating element and cause it to burn out and fail. You usually notice a decrease in the hot water supply as the lower element goes bad. You have to drain the tank, remove the lower element, suck out all the mineral deposits and then install a new element. The new element is only $25 but the process is a PIA. Good luck !