Some Cayucos residents could see a rate increase on their water bill, but not everyone in town will feel the impact.Three different water companies serve the town of Cayucos Cayucos Beach and Morro Rock are mutual water companies, while CSA10A is county-operated.Last month, CSA10A proposed a 74% rate increase. That would mean customers using more than eight units of water each month could see their bills go up by more than $150, but at a Cayucos…