Once a week we have to remove the water line from the washing machine and clean out the screen because it is clogged with a gritty sandy substance. As it clogs up it stops the flow of hot water into my machine. I'm trying to find out where this substance is coming from. Could it be coming from the water heater or from the water lines? The water heater was installed a couple years ago, it was brand new but it sat in storage for an unknown period of time. I have no idea how old it is.