Toilet (IMAGE) Penn State Caption Penn State researchers have developed a method that dramatically reduces the amount of water needed to flush a conventional toilet, which usually requires 6 liters. Credit Wong Laboratory for Nature Inspired Engineering, Penn State Usage Restrictions Non commercial use only License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.