Water meter-water company.  

City water with one main at the street and how will they bill. 

Quote from @Devin James: Quote from @Scott Mac: Maybe the infrastructure, electrical grid, water sewer, pavement thickness on the roads, cannot handle the extra people in the area.

Then wherever the water is getting discharged off of the roof, that what water is getting at least 4-5 foot away from the structure before it is left to drain with gravity away from the property. 

Usually if it is something no HoA I solve the issues but now the prolem is under the HoA mercy that seems to careless and the water damages are severe and scary on the photos.

What if you turn on water and it goes everywhere.

Locate sewer, old septic tanks,  and water lines.  4.  

:)As for LTR rental terms, usually we sign a 1 year lease where tenants are expected to pay Electric and Gas if applicable, while the owner typically pays water/sewer/trash with the city. 

I'm new to the real estate investment game and I'm a bit nervous about dipping my toes into unknown waters. 

Your question about hydrostatic pressure is getting into the weeds for sure...I would ask myself, does the potential water infiltration have the possibility to damage the unit and tenant property?