Hi Kevin,
It's good to hear you're planning things to do in Ireland. Yes, it would be possible to find day tours between Dublin and Waterford. There are many
travel operators in Ireland, who may be able to facilitate such a tour for you.
Through a quick Google search, it's possible to find a number of companies that offer related day tours. One such example is Waterford House of Crystal, which organizes day trips to Waterford from Dublin. You can find more information about this
here.
Regards,
Eoin