We have one sign on top of the toilet that kindly asks our guests to not flush anything besides toilet paper down the toilet because we are on a septic system.

It’s running fine now, but if tenants start flushing stuff they shouldn’t, a block in the pipe would be a huge ordeal.

low flow shower heads and faucetsnew toilets or "duo-flush" retrofits on old toiletscharge for laundry or no laundryno outdoor hose bibs

Each has 1.6gpf toilets (or 1.8, in either case, it's a lot of water per flush).

I do have in my lease regarding the septic and to ensure that they know not to flush anything besides toilet paper.

Since I am a land buyer I do accept newbie wholesalers sending me stuff .. but its just to get an address.. they offer nothing else of value other than the contact.. and its rare I would buy from a wholesaler simply because they have no clue as to whats involved with land use and development and they just waste all their time chasing a unicorn deal that has no chance of going anywhere.. land owners with for real development ground most of the time are going to flush out someone with no capacity and no knowledge of how to push these deals through entitlements.. 

@Megan Hadley i am happy to help in any way that i can. forget what Quicken said. i talked to them once and then they called me for months like vultures. they are very square in terms of their loan offerings. i stay far away from big banks.i am not normally flush with cash either. i utilize hard money and owner financing as many times as possible. i got into my first deal with FHA financing, 3.5% down and househacked my way to the next property. i do not do any traditional or conventional loans now though. let's talk. i am always happy to help. i also write articles for BP that you might find helpful. either way, let me know how i can help!

And one of the toilets is an older toilet with more water per flush than what a toilet bought today would use.Now if the OP is living in one unit, less rent will get collected; and one of those garages would probably be used to store stuff, meaning even less collected rent.

The upstairs had backups when the toilet was flushed and the shower was running, which prompted a line scope.

First of all, you are a landlord to make money, not just to provide people with housing or keep their toilets flushing for because you are good person.