Route 1 

10 digit account number beginning with '1'

March Bill
Billing Period: December, January, February
 Due: April
 
June Bill 
Billing Period: March, April, May
 Due: July
 
September Bill
Billing Period: June, July, August
 Due: October
 
December Bill
Billing Period: September, October, November, 
 Due: January

Route 2

10 digit account number beginning with '2'

January Bill
Billing Period: October, November, December
 Due: February
 
April Bill
Billing Period: January, February, March
 Due: May
 
July Bill
Billing Period: April, May, June
 Due: August
 
October Bill
Billing Period: July, August, September
 Due: November
 
 

Route 3

10 digit account number beginning with '3'

February Bill
Billing Period: November, December, January
 Due: March
 
May Bill
Billing Period: February, March, April
 Due: June
 
August Bill
Billing Period: May, June, July
 Due: September

 November Bill
Billing Period: August, September, October
 Due: December