Illinois American Water has filed a request for an 18 percent statewide rate increase for all of the water and sewer company's operating districts in Illinois. The request would increase the average company customer's base water and sewer service rate by $7.57 per month. The proposed increase is pending approval by the Illinois Commerce Commission. Company spokeswoman Karen Cotton says the commission's decision won't come until the end of this year. The company says the requested rate increase is driven by investments in infrastructure improvements statewide. Illinois American Water's last base rate increase was approved in 2012. The company's operating districts include Peoria, Sterling and Champaign County.