Negligence Issue With Tenant

[Zhihan Wan]

Hello, our rental home had a/c unit drains into the p trap in one of the bathroom and clogged the sink in upstairs. The tenants were out for 24 hours and came back found it and the water had already flooded out to the floor and the ceiling of 1st floor. So we have to replace the carpet and floor wood and cabinat board under the sink for that area, and repaint the ceiling. The lease was almost over at that time. Now the lease is end, they move out and want they want the deposit back. Should this issue be a partial responsibility for their absense while leaking and should we deduct some cost from them? Is there any laws address that? Thank you!