Awkward conversation: Female Insight Needed

[Jared Mann]

I am currently househacking my first duplex, a couple weeks ago I noticed the main sewer line was backing up slightly in the unfinished basement. I attributed it to the heaven rain fall we were getting at the time. This week it happened again with absolutely no rain, so I called a plumber to take a look. The snake cam revealed a blockage and the culprit was...feminine hygiene products. I am a mid-20’s guy and my tenants are 4 girls in college, so there is no ambiguity who caused the blockage. I am not going to take the cost of the plumber from their security deposit, but the main thing is that it does not happen again. Any tips for how to tactfully have that conversation with tenants I see every day?