There have been recent advances made in the technology of toilets, and the potential for significant water savings has resulted.

Let's examine a family of four. And assume that each person in the family flushes twice a day. Eight flushes per day for one year equals 2,920 flushes per year. Our bar chart compares water use with four different size toilets, also using a brick in the two largest tanks to see the savings realized there. Want to know how much water your toilet uses? Mark the water level in the tank with a crayon. Turn off the water supply and flush. Use a measured cup or bucket to refill the tank with fresh water up to the crayon mark you made. That's how much water is used with each flush.

At one time it was popular to save flushing water by placing a brick in the bottom of the toilet tank. As you can see on our chart, you can count on about a 5-percent savings from brick displacement - not as significant as the alternatives, but a savings nonetheless.

It is important to know that the toilet-tank reservoir size is carefully engineered at the factory to match the bowl size. This is so that there will be enough water held in the tank to generate a predetermined siphon at the toilet bowl when a flush occurs. Too little water in the toilet tank could result in improper siphon pressure and an improper flush or even clogs in the sewer line.

By indicating the minimal effect, we aren't suggesting that you shouldn't use a brick in your toilet tank to cut down on water consumption. We think any conservation measure is a good idea. Make sure to wrap the brick in a watertight plastic wrap. An unprotected brick will eventually begin to dissolve and might clog the toilet.

If you try the brick and it doesn't work, you might be reluctant to purchase one of the new ultra-low flow toilets. Since the new ones hold less water than your old brick-filled model did, you might figure that if your old one didn't work, the new one, with less water, couldn't possibly do the job.

Not so. The bowl of this new breed of toilet works beautifully -even with the smaller tank and reduced water input. If you can afford the air-assisted model, the flush is actually superior to almost all the previous toilets made. And the water pressure is so good that waste is forced farther down the sewer line than with some models using twice as much water.

These new toilets are somewhat expensive. Depending on brand and medel, ultra-low flow toilets can be purchased from about $150 to $350. With air-assist, the price is about $250 to $750.

Even though they are more expensive to purchase than old-fashioned models, they are every bit as easy to install.

First, turn off the water supply to the tank. Next, flush the toilet. Once emptied, disconnect the water supply line from the tank. Two nuts (one on each side of the base of the toilet) will have to be removed. To complete the job, straddle the toilet bowl facing the tank, reach under either side of the tank and lift. This job requires a certain amount of strength. To install the new toilet, simply replace the wax ring and reverse the steps in the removal process.

Many states already require ultra-low flow toilets. Conversion will support conservation where you live.