YUMA, Ariz. — Residents of the Tierra Mesa neighborhood say sharp increases in their water bills are straining household budgets, with some bills reaching hundreds of dollars. Some customers say their charges have doubled or tripled, and they worry they may not be able to afford future bills. Jesus Rosillo said his family has cut back on water use but continues to see higher bills. Residents who challenge large charges say they have sometimes been told a leak or heavy usage could explain them. Central State Water Resources President and CEO Josiah Cox said the company is investing in Tierra Mesa and other small communities that, in his view, went years without needed improvements. “These smaller communities that haven’t been invested in for decades are the ones we are focused on,” he said. The Arizona Corporation Commission approved a rate increase of at least 300% for the company. Residents say they understood the higher charges would help fund infrastructure repairs, but have not seen work taking place. Cox said some projects are difficult to see because they involve underground infrastructure or electrical and mechanical work inside facilities. Arizona Attorney General Kris Mayes has asked the commission to reopen the rate case and pursue lower bills for rural customers. Cox said the company will work to schedule a hearing with the commission and is aiming to hold community meetings within two months to answer customer questions. The dispute puts basic service affordability and accountability for promised infrastructure investment at the center of residents’ concerns. The available information does not specify the size of individual bills before the increase or provide a detailed schedule of the work underway.