Bought my house 10 years ago. It had a brand new hot water heater. We live in an area with hard water and lots of mineral buildup. For example, shower heads and dishwasher ducts clog up. I don't get my water treated with softeners by the Culligan man or anything like that. (Probably should but haven't done it). My electric kettle gets a nice layer of buildup that I have to remove with vinegar once in awhile. So I have a feeling that even though it's a good quality hot water heater and is working just fine that it's a) filling up with gunk; and b) maybe about to rust through and start leaking all over my garage. But do I just wait until it leaks, or is there another way to evaluate it and decide when it's time to replace it? I recall an earlier thread that suggests that since I haven't been servicing it that it is probably too late to do any preventative maintenance and that any attempts to do so might actually hasten its demise-- and therefore to just replace it when it's time to do so. But how do I know when it's time without waiting for a leak?