Tenant want to hire and pay for a plumber themselves

[Evan Hauler]

Hello, 

I just bought, my first ever property/home (woo), and there is an existing in the lower unit. And they have reported a slow clog in their bathtub, the thing is they offered to hire a plumber and pay for it themselves.

Ive never heard of anyone doing this, and was wondering if it is legal or what are my risks by allowing this? 

Thank you :)