If you are concerned about how much water you might be wasting in your toilet, then you need to think about how much water you need (versus how much water your toilet currently uses) every time you flush.
EPA WaterSense certified toilets are an obvious choice in sustainability. The most commonly found water-efficient toilets are those using dual-flush technology (examples here). By providing exactly the right amount of water based on the need to flush down either solid or liquid waste, a dual-flush toilet system conserves a tremendous amount of water. However, replacing your system completely can prove to be expensive in some cases, so another option to consider is converting your existing toilet with a dual-flush converter kit.
For example, SelectAFlush is a dual flush toilet kit and a water conservation device for standard toilets. The kit enables you to convert your toilet into a dual flush system enhancing the performance of your current toilet for a fraction of the price of a new dual flush toilet.
The average U.S. family of three can save 21 gallons of water a day, or more than 7,000 gallons of water a year with SelectAFlush. With a present US population of 300 million people, if dual-flush water-conserving toilet valves were installed on every home toilet, the U.S. could potentially save a minimum of 700 billion gallons of water annually, enough to fill more than a million Olympic-size swimming pools. It’s staggering to think of what that kind of savings could mean not only for the US, but for drought ridden economies around the world.