If you purchase a heat pump dryer or condenser dryer with a drainage option, you don't have to empty the water reservoir. The moisture is automatically drained via the water drainage with help of a condensation drain hose. It's important to have a water drainage present at the location you want to install the dryer. If you want to save on energy, you should purchase a heat pump dryer, which works via a heat pump and cooling agent. This is better for both the environment and your electricity bill.