Many people believe that laying a brick in your toilet tank saves water. In fact, it does nothing to save water because the brick is always below the surface of the water.
To visualize exactly what happens, take a look at the sketch.
Before you flush, the tank is filled to the upper-level water line in the sketch. When you flush, it drains to the lower-level line. At this point the flush valve closes and the tank refills to the upper level.
Let's say that the volume of water between the upper and lower levels is 7 gallons. Every time you flush the toilet, 7 gallons drain out of the tank, then 7 gallons flow back in to refill it. Laying a brick in the tank as shown, so that it always lies below the lower water level, doesn't change this fact.
That volume remains 7 gallons. The only way to change the volume of flush is to change the volume of the tank between the upper and lower water levels. Laying a brick in the bottom of the tank is no more effective than laying it on the floor, taping it to the ceiling or leaving it at the brick yard.
OK, if laying a brick in the tank won't help reduce water use, what will? One simple way to get the job done is to bend the float arm down a bit. This will lower the upper water level, and quite obviously this will reduce water use.
This isn't such a good idea, however. Because when you lower the upper water level, you don't just reduce the volume of the flush. You also reduce the force of the flush because you have reduced the height from which the water falls.
A better approach is to leave the water levels as they are, but introduce a space killer between the upper and lower water levels. You could, for example, stand a brick on end so that at least part of it extends above the lower water level. Then, every time you flush, you'd save a volume of water equal to the volume of brick that extends above the lower level.
But a brick can disintegrate and start to interfere with the mechanics of the toilet. Something better is called for. One thing you can use is a tall glass or plastic bottle. Fill it up with sand and water, cap it and stand it in the corner of the tank.
Just make sure it doesn't interfere with the operation of the float arm.
If there's space, you can put a bottle in each corner. But again, fill these bottles with something heavy (such as sand and water) so you can be sure they won't shift around and block the flush mechanism. If they do this, they can waste more water in a single day than they can save in a year.
There are also some commercial approaches. Some plumbing shops sell special dams that you can wedge into your tank to reduce its volume. These work well enough, but in my experience, it's hard to find a shop that stocks, or even knows about them.
Of course, the most effective way to reduce water waste is to buy a specially designed water-saving toilet. All toilet-makers offer these. In fact, they are required in many parts of the country.
Sure, they cost more than putting a brick or a bottle in your tank. But because they are designed expressly to save water, they'll save more than jury-rigged retrofitting will. And they'll also give you a good, clean flush, something you often don't get when you modify a standard toilet.
(c) 1989, Los Angeles Times Syndicate.