The nearly 24,000 Western Municipal Water District customers can expect to see their water bills rise on average about $15 to $20 a month after this week’s approval of phased rate increases. Residential customers in the Riverside area should see bills climb an average of $14.63 per month by early 2020, with a first incremental bump of $4.64 in January, a district report states. Customers in Murrieta are in for a hike of $19.24 over that period, starting with a $5.98 increase in January.