The average low flow toilet uses 1.6 gallons per flush.
Yes, George Bush Sr. signed the low flow toilet law in 1992 which was enacted in 1994. The low flow toilet basically stated that toilet can not flush more than 1.6 gallons of water.
Yes, there is check with your local government to see if they are giving "low flow rebates". The typical rebate is usually between 50-100 dollars. There is rumors that California was giving free low flow toilets which is actually somewhat true. In the Rancho California Water District during 2008 they were actually installing and giving away low flow toilets. What a great deal!!!
There are two ways to tell some toilets have the gpf (gallons per flush) on the back of the toilet. It would say 1.6gpf on the toilet or inside the tank for the gpf. If neither of those are present than perform the following steps to measure the amount of water your toilet flushes.
1. Take of the tank and measure the amount of water in the tank. Than record the height of the water level in inches.
2. Flush the toilet with the measurement device still in the tank. Now record the inches of water the toilet has when it is at its lowest flushing point.
3. Subtract the two water measurements and this will give you the Height.
4. Measure the length, width, of the toilet tank.
5 Now multiply length x width x height= flush volume
6. Finally divide the flush volume by 231 to convert the inches to gallons. {Source: How to you know if your toilet is a low flow toilet}
If your toilet flushes 1.9 gallons or less than you have a low flow toilet. This is also how you know if you qualify for your city's low flow rebate program. I know this is a pretty intense process but it is worth it.