You never want to see rust or other types of corrosion appearing on important metal appliances or fixtures. It’s bad news because corrosion weakens metal and eventually causes it to deteriorate and flake away.
Because a water heater is a mostly metal device that holds and circulates water, it’s in jeopardy of rusting. Thankfully, water heaters have special defenses built into them to prevent rust and other types of corrosion from getting an early hold on them. These defenses include the sacrificial anode rod that attracts rust to it rather than the tank; the expansion tank that keeps oxygen out of the main tank (corrosion requires oxygen to trigger the chemical reaction between water and metal); and a glass lining inside the tank.
Yet seeing that your water heater has rust on the outside can still happen. When you see rust on your home’s water heater, does this mean the water heater is finished? Is it time to call us for a water heater replacement?
A broken water heater means an unpleasant day. People often discover they have a failed water heater in the morning after they get up, go to the shower, turn on the tap … and the water never heats up.
You need your water heater working steadily now more than ever. And that means it’s more important than ever to stay on top of potential water heater problems and their signs. The faster you schedule 
When water meets metal, there’s a chance for rust to start. Although water heaters are in danger of corroding, they’re manufactured to resist rust for many years. If you keep up with regular maintenance for your home’s water heater, as well as calling for water heater repair in Fresno, CA when needed, you probably won’t encounter signs of rust until the system is into its second decade.
Water heaters are built to last for years without suffering leaks, corrosion, or drops in performance. But no water heater is designed to last forever. Depending on how old your current water heater is and how well it’s been maintained, you may soon find yourself needing to have the unit replaced.