I agree with "JustBill" there shouold be no correlation between your hot water heater and the water softener and your PRV should not have caused any internal leaking. I would suspect a incoming pressure problem from your water source. Your incoming water pressure should be around 60 psi and anything drastically above that can cause damage to appliances, fixtures and the WH. I have a blog about the danger of too much water pressure appearing currently here in the DIY Blogs. Click on "DIY Blogs" on the task bar at the top of the threads and read it, maybe it will help you understand.