The most important part of my service is replacing the anode rod which is the key to water heater longevity. This solid magnesium bar is what corrodes away to protect the tank metal from rusting. The anode rod should be replaced every 5 years to maintain rust protection. If you have a water softener the anode can be consumed in half the time of 2½ to 3 years so a second anode is added for $35 more to provide double corrosion protection. New 5 year warranty tanks come with one anode and 10-year warranty tanks have 2 anodes. The secrete to water heater longevity is replacing the anode every 5 years so the tank is never left unprotected to rust away. So don't spare the rod and spoil the tank. It’s best to spoil the rod and spare the tank.