No matter how stingy the showerhead, taking a hot shower can be like pouring money down the drain. The EcoDrain shower heat exchanger reduces the waste by capturing heat from the wastewater and using it to preheat the incoming cold supply. According to the maker, the product boosts the temperature of the water flowing into the cold side of the mixing valve from the typical 50°F to 85°F or more, cutting water-heater use for showers by 25 percent to 70 percent. It retails for $499. EcoDrain, 514/448-4798, ecodrain.com