That depends on various factors. First it depends on the size of the toilet bowl and secondly the country in which you live is another factor. But generally it is believed that every time one flushes the toilet the amount of water used is about 3 to 4 liters (3,000 to 4,000 cc). In some developed countries like Japan and Singapore, the amount of water could be much less because in these countries water is a very precious resource. The flush system of their toilets has to be modified to make the flushing more efficient and effective.