Tenant wants to put a hot tub

[Aaron Xie]

The tenant wants to put a tub in the back yard. 

They will pay for the purchase, installation, usage and maintenance of the tub. They will also be responsible for any possible damage to the house (such as leakage). When they move, they will take it with them, fill the land, and put new sod on the ground. 

I did not see any problem with that, so have verbally agree with it. But would like to post it here to get a second thought from BPers before we put it on paper. Thanks in advance.