Newer dishwashers cycle the same water through repeatedly during the wash cycle, only bringing in fresh a few times during the process. Old ones from before they were concerned about water efficiency would just pull in fresh water and drain out dirty water instead of cycling the same water through repeatedly during each phase of the process.
Because they only run clean water it takes less runtime on the older dishwashers but they’re also constantly pulling in fresh water. It’s also why newer dishwashers require more cleaning out filters - they don’t just drain to the drain, so they need to care that the water draining won’t gum up the sprayers and such because it’s going to go back through. The point is that they use much less total water to get the job done.
Newer dishwashers cycle the same water through repeatedly during the wash cycle, only bringing in fresh a few times during the process. Old ones from before they were concerned about water efficiency would just pull in fresh water and drain out dirty water instead of cycling the same water through repeatedly during each phase of the process.
Because they only run clean water it takes less runtime on the older dishwashers but they’re also constantly pulling in fresh water. It’s also why newer dishwashers require more cleaning out filters - they don’t just drain to the drain, so they need to care that the water draining won’t gum up the sprayers and such because it’s going to go back through. The point is that they use much less total water to get the job done.