If the water is surface water, almost always it can be solved by properly grading around the foundation, being sure that gutters are installed and drain downhill from the house, and (when necessary) a toe drain around the foundation. 

It just doesn't take much more than a couple of day laborers and some tar to dig out and tar a foundation if thats the issue, if its a runoff issue, just know that water flows downhill and divert it. 

As SOON as you see the place going down hill, FILE for eviction.

Additionally, if anything breaks or you have unplanned additional vacancies, I can see this going downhill quick.

I mean, I know advice on BP has been rolling downhill for a while, but this would take the prize!

In case you need more convincing that we are heading down hill, take a look at the rent map in SOMA in San Francisco....

If the property has a downhill driveway I would consider flood insurance as well. 

Once you get one to two properties paid off it becomes a snowball rolling downhill, you can't stop it unless your an idiot.  

I can’t answer that exactly but it starts to go downhill quick at 150k 

If your doors and windows work, you can set things on kitchen counters to cook without it falling off, and don’t feel like you’re walking downhill...then that is functional and should be the goal.