After 5 months we had a bad water leak under the house.

Maybe the P trap under the sink is not filling with water correctly and allowing sewer gas to come back in.  

One misstep and you could be in hot water. 

Then based on @Michael Baum's suggestion, I think I will have my cleaner and/or maintenance person do monthly/quarterly maintenance like using using enzyme based cleaners, grease fighting drain treatments and hot water flushing. 

It had 22 of the 25 lots occupied but we'll be fixing it up, filling it up, billing back water and raising rent up to market.

If there are pets in the unit take a pan from under the sink and fill it with water so there's something to drink.

Just starting out and testing waters for BRRR in Chicagoland area.Any advice or suggestions regarding this?

What is the best overall water metering company you have found when it comes to ease of installation, reliability, and the cost of the equipment and monitoring?

A buddy of mine just built a duplex on the water in Placencia

I don't recommend throwing the baby out with the bath water, and definitely make sure you understand the nature of the Mentor you choose.BP is a great resource to meet some amazing people.