Why is it important to flush the water heater? Well, your water has minerals. Your water has calcium, calcium and minerals build up at the bottom of the tank. So you want to have it flushed. You want to actually have that tank flushed once a year To basically preserve the life of your water heater 'cause you're flushing out all that sediment. If you don't flush it, it decreases the lifespan of the water heater. It raises energy costs to heat up the water 'cause remember that sediment at the bottom of the tank, you're heating up the sediment before you're actually heating up the water. So, flushing it increases the lifespan of the water heater and reduces energy costs.