i think tb is the closest the anoid rod in the hot water heater is going bad it will have a sulfer smell and the pressure on the hot water will lessen from it braking down or scaling up but dp is right you do need more info to be sure like how old is the hot water heater like is the cold water pressure low also do you have a boiler with a heat excanger do you have copper or steel pipes so you do need more info just a thought that was rude dp it is hemoroids.....RICK