To ensure pet safety with Christmas tree water, covering the water basin is essential. Many tree preservatives, pesticides, and fertilizers used in the water can be toxic if ingested by pets. Use a tree skirt or a cover to block access. Alternatively, opt for a pet-safe tree stand with a covered water reservoir. Continuously monitor the water level and quality, ensuring it's free from harmful substances. Regularly check that the cover is secure to prevent pets from drinking the water, as plain water can harbor bacteria over time.