Putting water on a Christmas tree is a common tradition to help keep the tree hydrated and prevent it from drying out too quickly. To do this, you'll need a large bucket or tub and a watering can or pitcher. Fill the bucket or tub with room-temperature water, then place the tree in it so that the trunk is submerged. Let the tree sit in the water for several hours, or even overnight, to allow it to fully absorb the water. Once the tree has had enough time to soak, remove it from the water and set it in its stand, making sure to water it daily or whenever the soil feels dry.