A water heater is a necessary household appliance, but it can be expensive to replace. If you are unsure whether or not your water heater needs to be replaced, look out for these warning signs:Leaks: One of the most obvious warning signs is a leak. If you see water pooled around your water heater or coming out from under it, it is time to replace the unit.Age: The average lifespan of a water heater is 10-12 years. If your water heater is 10 years or older, it is likely time for a replacement.Rusty Water: Rusty water can be a sign that your water heater is corroding and needs to be replaced. This usually happens when the water heater reaches the end of its lifespan.No Hot Water: If you are not getting any hot water, even after running the hot water for a while, your water heater could need to be replaced. This could also be a sign that there is something wrong with your heating system as a whole.