My toilet seems to waste water like crazy. The lever has to be held down until the paper disappears, and the flush seems very wasteful (the way the water swirls for a long time before it goes down - that probably doesn't make sense, but I don't know how else to say it). I'm not sure putting a brick in the tank would help this problem. Does anyone have any experience in lowering water use in a high-water-use toilet? Buy a new one is not feasible (we're renting, anyway).
It would appear that no one has an answer to this. Ah, well, I don't either. That's why I asked. In keeping with the question, though, I think an outhouse (where it is legal) or a compost toilet would be the best way to lessen water use in toilets.
You can use a brick or two to displace the water in the tank, causing the float mechanism to turn off the water sooner. It sounds like you could also use a replacement flapper (I think that's what it's called). Or, the length of the chain connected to the flapper needs adjusting. It's a simple and cheap thing to adjust or replace. This can also be the source of most toilet leak problems where the flapper doesn't properly seal the opening. Water slowly leaks out and causes the toilet to periodically refill to replace the leaked amount.
I found limicid's comments very useful, especially about the "flapper replacement." If you don't have a brick, you could also use a plastic bottle filled with pebbles or sand, and place it in the toilet tank to displace the water.
Well, I put a brick in our tank and it works! You may be skeptical about this but at least you'll be able to save at least a bricks worth of water everytime you flush. If you have a big tank put in two. Adjusting the chain would also help. We are also renting. It would be a waste of money to change the tanks since we can't bring it with us when we leave.
I found that changing the little rubber flap in the toilet tank and adjusting the little chain made my toilet flush better and not run and waste water. The hardware store sells the little rubber flap and the chain. You don't need any special skills, just remove the little rubber disc and chain that are there and replace them with the ones in the package. Make sure you have a tight seal so that your toilet doesn't keep running water.
Nowadays you can buy toilets which are more water efficient but they are quite expensive. Water is the most valuable resource on our planet but I don't think you should bother worrying about the water used when you flush the toilet. Some things are out of our control, even though we would like to help and do our bit for the planet.
I have never tried it, but I have read that the brick idea works well. If you don't have a brick handy you could try filling an empty plastic water or soda bottle and using that to displace the water. The tank will think it is full sooner and use less water. Be careful messing with the flapper chain; they have a tendency to come loose and that becomes a pain for flushing.