If you’re like most people, you probably don’t really know where the money you spend on utilities is actually going. You just get a bill in the mail every month and hope it isn’t too high. Sure, you know that your air conditioner uses a lot of energy because your electricity bill skyrockets in the summer. But how much electricity does your refrigerator use? How much water does your dishwasher consume every time you run it? Those questions are hard to answer, but you can at least build this Arduino-based monitor to find out how much money you’re spending on water in the shower.