The chemicals in the water destroy the Polybutylene Pipes from the inside going out.  

A lease is a binding agreement on both sides and I don't see a tenant agreeing to a harsher penalty than you have them signed up for and honestly I wouldn't even bring it up. 

Talk to your insurance agent about the correct commercial STR policy that would also cover the pool.Then just put all the normal stuff, like no glass around pool, no diving, no lige guard swim at your own risk etc.Have a licensed insured pool company maintain it so you don't get sued for improper chemicals.

Also, if Drain-O is used and the plumber still needs to be called you must disclose that you used a highly toxic chemical.

@Justin Dar  You definitely don't want someone dumping hazardous products on your lot such as oil and any other harsh chemicals that could potentially contaminate the ground water.

My main business though is chemical manufacturing and we're looking to expand via purchasing a building.

Pool chemicals, service calls, broken furniture, dishes, etc. all add up. 

The downside to swimming pools is even at apartment buildings, almost nobody uses the pools in Los Angeles County throughout the entire year with the exception of a few times and they cost about $3000 per year to maintain with a pool cleaning company, chemicals, electricity and equipment replacement and repairs.

There are chemicals that kill the roots, but you need to be careful if you go that route.

@Stephen BrownFor starters, find local chemical distributors and call a few of them.