BATHROOMS : Save Water and Get a Handle on Types of Low-Flow Toilets

New energy standards mean that any new toilet you buy will use less water.

The National Energy Policy Act of 1992 mandates that all new toilets manufactured in the United States or imported for residential use must be low-flow.

This means that toilets cannot use more than 1.6 gallons of water per flush--compared to standard water-saving toilets that use 3.5 gallons per flush.

Most toilets manufactured in the 1970s or earlier use five to six gallons per flush.

There are three main types of low-flow toilet designs.

* The first type is the gravity toilet. In the past, toilets relied on gravity. Some of the new low-flow models still work on the same principle. They simply have steeper sides that increase gravitational pull to compensate for smaller water capacity.

* The second low-flow variety is the pressurized-tank toilet. A separate pressurized tank contained within the toilet tank pushes water into the bowl at a high velocity when the toilet is flushed.

* The third type of toilet features an electrically operated pump to quickly push water to the bowl.

Which should you buy?

Most plumbing experts say that new low-flow gravity models are adequate for home use (although they may require an occasional double-flush).

The pressurized and electrically pumped models offer more flushing power.

Gravity models tend to cost less than half of what their more powerful competitors cost.