The steam dryer will require water but you won't need to install another water line. The dryer comes with a kit that will enable you to connect to the existing water line to the washer. It will come with a connector to hook up the dryer to water.
The image below is from the owner's manual and it will give you an idea of how the dryer is hooked up to the water supply.
I hope this answers your question but if you have other questions then submit another question with any additional detail for further assistance.