How to address water usage/bill on duplex

[Shawn Reidy]

I'm writing in hopes of getting some advice about how to tackle a situation that I'm dealing with regarding the water bill.  Here's the background:

-I recently purchased a duplex and am occupying one unit and renting the other

-Currently, the owner (me) is footing the water bill for the building

-My unit has in-unit laundry, the other does not

-The water bill averages $200/month

I'm considering the following options and would really appreciate any advice on how you would handle the situation:

1) Once I move out, continue to pay the water bill (expensive over the long run)

2) Work in a flat fee to the rent and pay the difference myself each month (tough sell to tenants)

3) Install a secondary meter and charge tenants back at the end of each month for their usage (requires more work on the part of the property manager, hassle to charge precise bill to tenants each month)

4) Run a second water line, completely separate bills and make the tenants completely responsible for their own water bill (most expensive, initially)

What are your thoughts, and can you think of any better options to deal with the issue?  Any and all input is greatly appreciated.  Thanks!