Upon the enactment by the United States Congress of the 1992 Energy Policy Act, it became mandatory that all water closets in residential and commercial settings reduce the volume of water that they consume per flush. In 1994, after installations began of the new low-flush or low-flow water closets that used less than half the water that their predecessors used, many owners of the new plumbing fixtures began to complain that their performance was sub par. Many complained about plumbing backups and of complete bowl clearance problems. There have been studies conducted to evaluate the new water closets’ bowl evacuation properties. This study focuses on what happens to the solid waste that is flushed through the water closet after leaving the bowl, namely how far the solid media is transported down waste piping. The main focus of this study is to compare the performance of the low-flush, 1.6 gallons (6 liters) per flush water closets with the performance of the formerly standard flush 3.5 gallons (13 liters) per flush in regards to how far they transport solid waste through waste lines. It was found that the media flushed through the high volume water closets traveled significantly farther that the media flushed through the low-flush water closets. It was often more than double the average distance. It was also found that media traveled farther down pipes composed of PVC than those composed of cast iron and also traveled farther down three inch pipes than four inch pipes.

Collection of sewage from toilets in a closed tank provides good protection for the environment and health. The closed tank reduces emissions of fertilizing substances, and other substances that may pose a risk, such as pathogens and drug residues. To reduce the water volume in the tank, it is advantageous to connect an extremely low-flush toilet, which means that the average flush volume is a maximum of 1 liter per flush. It is important that the toilet system is reliable for the technology to be used to a greater extent. This study examines experiences and functioning of extremely low-flush toilets to identify possible deficiencies and possible areas for improvement. Information has been obtained through telephone interviews and online surveys. The result shows that most respondents are generally satisfied with their extremely low-flush toilets. For the system to function optimally, it must be properly installed and maintained. There are some deficiencies that are more common, such as interruptions caused by flushing of incorrect objects or incorrect installation, but also some occasional errors. Many malfunctions appear to be caused by improper use or installation. There may be a need to develop certain technology components, such as the alarm function. The sound when flushing can be perceived as too loud. It is important that there are clear instructions for installation, maintenance, and use, as well as functioning service networks in case of problems.