High volume flush vs. low-flush water closets and solid waste transport distance: a comparative study

摘要

Upon the enactment by the United States Congress of the 1992 Energy PolicyAct, it became mandatory that all water closets in residential and commercial settingsreduce the volume of water that they consume per flush. In 1994, after installationsbegan of the new low-flush or low-flow water closets that used less than half the waterthat their predecessors used, many owners of the new plumbing fixtures began tocomplain that their performance was sub par. Many complained about plumbingbackups and of complete bowl clearance problems. There have been studies conductedto evaluate the new water closets? bowl evacuation properties. This study focuses onwhat happens to the solid waste that is flushed through the water closet after leaving thebowl, namely how far the solid media is transported down waste piping. The main focusof this study is to compare the performance of the low-flush, 1.6 gallons (6 liters) perflush water closets with the performance of the formerly standard flush 3.5 gallons (13liters) 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 closetstraveled 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 mediatraveled farther down pipes composed of PVC than those composed of cast iron and alsotraveled farther down three inch pipes than four inch pipes.