Water will not stay hot for more than ten min

Gas or electric? If it's electric check the elements starting with the bottom one. If the elements check out then remove the cold water supply and check the dip tube. Let me know what you find. Good lock, Tom

IF electric, do as tom says, and if gas, still check the dip tube. Also, flushing the water heater may help. Im assuming you are experiencing shortage of hot water only while showering?

All good answers, if not sure how to check that dip tube just ask.