Baltimore water bills and tenants

[Nicole A.]

For those of you investing in Baltimore County Maryland--and especially with multi-units--how do you handle the water bills?

-Do you pay it yourself and "include" it in the rent?
-Do you have a method of determining which unit owes what per bill if it's not separately metered?
-Is it legal to say in a lease that if the water bill is above $XX amount, that the tenants owe the difference?