Shared water meter and previous lease interpretation

[Carl Hewitt]

I bought my first rental property and inherited tenants. Unit A is in the front of the property and an in-law suite is in the back as Unit B. The have separate electrical meters, but share a water meter. 

My question is in the interpretation of the signed lease agreement that the tenant in A has under the previous owner. I pay for all utilities for Unit B, since it's section 8. For Unit A, the tenant pays all utilities "except for water $100 per month - tenant pays the difference." My thinking is that Unit A doesn't pay the initial $100 because that is reserved for me to pay for Unit B, however Unit A has to pay anything over $100. I believe the average bill is at least $200/month. 

My property manager believes that section means that I pay $100 for Unit B and then on top of that $100 for Unit A. So anything over $200 Unit A would pay essentially. 

[Kelly DeWinter]

call the previous owner and ask for a written explanation on what was being paid by whom.