Tenant Deposit. Water Damage. Negligence?

[Daniella Hernandez]

I am a new real estate investor. I just had my first tenants moved out after renting my first unit for 15 months. A few months ago, they reported water damage. By the time I was notified the whole master bedroom laminate floor was ruined. They blamed it on the bathroom shower doors not being installed correctly. This happened after they lived in the apartment for 13 months. After they moved out, we realized the water damage covered the whole master bedroom (16 ft), so I have to replace the whole floor. I have not given them their deposit back. My rental home insurance does not cover tenant negligence. We have sent plumbers and restoration companies and the conclusion is that it was the tenants negligence. The tenants is blaming me for not having the doors installed correctly. The plumber that went to help 2 hours after they reported the incident said said they had wet towels on the floor and that  he believes the bathroom doors had fallen and they installed them back incorrectly. Not sure what to do to prove that their negligence is going to cost me more than their deposit. I don’t think they should get their deposit back. Any advice and/or guidance would be greatly appreciated. Thank you in advance.