I think the scope needs to be flushed out here.  

I would just tell them not to flush the toilet. 

If you're making a ton of money reselling stuff, you're not even going to be interested in this until you're too flush with cash to reinvest it in your sales business.

The old tale that tenants will call you at 2 am about their toilet, not flushing is possible--but very rare!

Learned that one the hard way, just because they can not flush the toilet, does NOT mean they stop using the toilet.

She has cussed my manager out more than once; flushed stuff down the toilet causing a plumbing bill; & constantly leaves cigarette butts on the ground outside despite being a non-smoking property. 

This ensures the A/C lines get flushed, filters are changed, plumbing lines are tight, etc.  

Pets can also be a source of innumerable problems with housemates; for instance, a dog might make noise that bothers the housemates...if a pet damages belongings, or bites a tenant, you're liable...tenants with cats often flush cat litter down the toilet, which can block the sewer main...housemates might start to complain about the dog crap in the back yard, etc., etc..

When you "flush" solids down the commode with almost no water, it gets clogged in the sewer line.

Flushing them out into other areas only screws up someone else's neighborhood.