We are planning a bathroom remodel and want a separate bathtub and shower. We have one , inch and a half drain line now. Should we run a two inch separate drain for the shower or can we use the existing drain line for both fixtures?

We are planning a bathroom remodel and want a separate bathtub and shower. We have one , inch and a half drain line now. Should we run a two inch separate drain for the shower or can we use the existing drain line for both fixtures?

Because of all the grease and hair that goes down the drain I'd pipe the shower in a separate 2" drain line and I'd connect it to the lavatory drain where it will be wet vented. If you don't then a separate vent for the shower will have to be installed. Good luck, Tom