Water Quality Most of the time, the water you drink, or the water you interact with, is rarely composed of only H 2 O molecules. Water quality is a measure of the substances in water other than the water molecules.
Water Quality The government sets concentration limits for some substances such as arsenic, copper, lead, or coliform bacteria (such as E. coli). A concentration is how much there is of one substance in a certain volume of another substance. Concentrations are often measured in parts per million (ppm).
Water Quality The pH of water also affects its quality. The pH is a measure of how acidic or alkaline the water is. pH is measured on a scale of 1-14, with 1 being the most acidic and 14 being the most alkaline. Neutral is 7.0 on the pH scale.
Water Quality Calcium and Magnesium are two minerals that can be found in water as well. These two minerals are not harmful to humans, therefore are not regulated the same way. The hardness of water is a relative measurement of the amount of Ca and Mg in your water. Hard water does not form suds easily (meaning more detergent is needed) and can also form deposits that can clog pipes and machinery.
Water Quality The presence of disease-causing organisms also affects water quality. The Escherichia coli bacterium (E. coli) can be found in human and animal wastes, and when present in the water supply, it can indicate that the water has not been filtered properly.
Treating Drinking Water Water treatment is a way to make water safe to drink. Water treatment often takes place in a water treatment plant. The first step of drinking-water treatment from a lake/river is usually filtration. Filtration is when water is passed through a series of screens. The screens do not allow large objects to pass through.
Treating Drinking Water The second step is coagulation. Coagulation is when a chemical is added to water to make particles stick together. The chemical (alum) causes sticky globs (flocs) to form. These globs sink the bottom of a settling basin, and then the water is filtered again. FYI - coagulation is also what your blood does to form clots and to stop bleeding. Exsanguination would be a bad thing.
Treating Drinking Water The next step is to add chlorine to the water. Chlorine is a strong base (alkali) that kills microorganisms that can cause disease. Forced air (aeration) is pumped into the water to reduce unpleasant odors and tastes. Sometimes sodium (Na) or lime will be added to water to soften hard water, and fluoride (F - ) is added to prevent tooth decay.
Treating Wastewater Wastewater and the different kinds of waste in it are called sewage. In most communities, household wastewater flows into a system of pipes called sanitary sewers. The sanitary sewers carry the wastewater to a wastewater treatment plant.
Treating Wastewater Some people treat their sewage using a septic tank system. A septic tank system has an underground tank where bacteria are used to break down materials in the water as the water passes through the tank. Rid-X ® is a commercial product that adds necessary bacteria to a septic tank system.