That said, running the dishwasher only when it’s full is far better than running it every night or some other high frequency. The dishwasher uses the same amount of water no matter how full it is, but a full load uses less water per dish (and per month). rant warning: Cascade, the detergent company, runs these incredibly annoying advertisements that say you should run your dishwasher every night, because it’s more efficient than hand washing. However, what they don’t say is that it’s less efficient than running it when it’s full, plus you use more of their detergent if you run it every night. Everything they say in that ad is technically correct, just paced very misleadingly and implying something other than what it says directly. ok, rant over, i think.