DO NOT LEAVE EMPTY CUP ON THE BUDDHIST ALTAR
Question: If we will be away from home for a period of time and there is no one available to change the water offerings, is it alright to leave the cup used for water offerings empty while we are away?
Answer: No, you can’t. It is absolutely unacceptable to offer empty cup as it is disrespectful.
Source: Master Jun Hong Lu’s Discourse (Question 324), 24 July 2019