Like Energy Star, WaterSense is an EPA backed program specifically aimed at water conservation. This program provides consumers with an information resource and an easy way to spot water efficient products like faucets, showerheads and toilets via the WaterSense Label.
The EPA designed this program with the understanding that consumers might want to conserve water but would probably not do so at a sacrifice to comfort. Products that they endorse with their stamp of certification are guaranteed to reduce water use by at least 20% while maintaining the practical standards of traditional plumbing fixtures. What would be the point of having a water efficient toilet if you needed to flush it twice every time you used it, right?
Savings from these appliances will stack up too. Using less water with your faucets and shower not only saves on your utility bill but also means less water needs to be sent through your water heater, which will reduce the cost of your electricity bill. The EPA even has a handy savings calculator so that you can calculate your savings for 3 months or up to 10 years depending.