proration of chicago water bill.  You can prorate a chicago water bill.  To prorate simply request the prior years full bill which is two six month bills. Then divide the total year bill by 360 to get the per day cost.  Then count the days from when the last bill was issued.  Use following equation to caluculate the credit that should be given to buyer at closing

X = number of days since last bill issued

Y= the cost per day for water 

Z= the amount of credit given to buyer at closing

Equation

(X)(Y)=z

Example

Sellers received a water bill for $318 dated February 8, 2014 and another water bill for $324 dated August 18,2014.  Sellers have signed a contract to sell the home to buyers closing on January 31 2015.

To determine coat of water per day, add the two water bills issued in 2014 for 2014 water cost and the. Divide by 360

(318 + 324)/360 =1.783

To find out credit that should be issued to buyer calculate where 134 is the number of days since last bill in August through date of closing

(134)(1.783)=238.92

The credit at closing will be $238.92