High-efficiency toilets (HETs) have been defined by the plumbing industry and the Environmental Protection Agency (EPA) as those that use an average of 20 percent less water per flush than the industry standard of 1.6 gallons.

For a family of four that can mean a savings of almost 9,000 gallons of water each year. That's not only green, but it also makes sense, especially in an age where public water prices are on the rise and aquifers are being depleted.

PATH highlights four styles of HETs on its list. The gravity-fed single flush toilet operates like your traditional bog but can use as little as 1.1 gallons per flush.

For those who want options when flushing, the dual-flush toilet allows you to choose between one mega flush that uses up to 1.6 gallons of water or the more modest light flush that rinses with .8 gallons. These toilets average out to be about 1.2 gallons over the course of a year.

Next on the list of suggestions is the pressure-assist toilet that uses water line pressure or a small air compressor to force the 1.1 gallons of water through the bowl at a much higher rate of speed. These toilets can flush greater loads faster at a significantly lesser volume of sound.

The final HET suggested by PATH is the power-assist toilets that operate using a pump to force water down at a higher velocity than gravity toilets. Power-assist toilets require a 120V power source to operate the small fractional horsepower pump. Typical flush volumes are between 1 and 1.3 gallons per flush, and dual-flush models are also available.