Water Meter separations

[Kay Rock]

Good afternoon, 

 I have a duplex and i contacted the city about getting separate water meters,  to get the job done they gave me a quote of $2900. I was wondering if there is another way to know which apartment uses what, since it is so much to do the separation. I have in the lease that the water bill will be divided by to 2 units, but one of the tenant has a washer and the other one does not. 

Thanks in Advance

Kay.