Yes, it is possible to overwater a Christmas tree. Overwatering can cause the roots to rot, leading to the tree not being able to absorb water and nutrients properly. Signs of overwatering include yellowing leaves, wilting, and a lack of growth. If you suspect that your tree is overwatered, you can reduce the amount of water you're giving it and allow the soil to dry out slightly before watering again. Additionally, you can try moving the tree to a different location that receives less direct sunlight or has more airflow to help prevent root rot.