Tenant now requests a water softener (we live in a very hard water area) due to clothes not being clean, stains, etc.

In these instances, you'd have to check things like flooring, plumbing for leaks, roof for leaks, hot water heater, and heating and air conditioning units. 

No question RE is a long game and those who try BRRRRR (I add the last R because there should be one called "Reserves") with $200 cash flow in low cost areas are generally going to be blown out of the water in short order.

They will get a $100,000 liability to cover fires, water damage, accidents, and more.As @Greg Scott stated, you should require your tenant to add you as "additional insured" on their policy.

What happens when the water service line has to be replaced?

If you can get a house with a killer view I think that is what sells the most, second being on water. 

All of that is going to be very helpful while navigating new waters.

Water submetering is more difficult with smaller properties; especially older ones. 

I’ll give the water company a call on Tuesday.

I normally recommend using a Property Manager who works with the program regularly to help navigate the waters.