CHAP. 2.2 – WATER TO DRINK

WATER TO DRINK Drinking water comes from either a public or private water supply. Large communities maintain a public water supply where they collect, treat, and distribute water to residents. Less-populated areas often rely on private wells to supply water to individual families.

I. WATER QUALITY A. STANDARDS OF QUALITY Def. of Water Quality: the measurement of the substances in water besides water molecules. Iron is often present in water but it is not dangerous unless it is found in high concentrations. Iron can affect water’s color (yellow to rusting orange in color) and its taste (taste like rotten eggs).

Other things found in water are chemicals (such as fluoride) and microorganisms. This can be harmful or helpful. The U.S. Environmental Protection Agency set the limits and standards on what can be found in water. The limits and standards are termed levels of concentration. SEE FIGURE 5 ON PG. 58. Def. of concentration: the amount of one substance in a certain volume of another substance.

B. ACIDITY The pH level of water also affects its quality. The pH of water is a measurement of how acidic or basic water is on a scale of 0 – 14. Pure water has a pH of 7 – it is neutral (neither an acid nor a base).

Over 7, the water is leaning to be more basic. Under 7, the water is leaning to be more acidic. Acidic water can cause problems by dissolving lead or other metals from pipes it passes through. This can be toxic and corrosive.

C. HARDNESS When looking at the hardness of water, you are looking to how much calcium and magnesium is present in the water. Hard water contains high levels of calcium and magnesium that come from rocks (such as limestone) that water flows over underground.

Evidence of hard water is that it does not mix well with soap and detergent to form suds. Suds are necessary for effective cleaning. Therefore, in order for cleaning to work, you need to use more soap and detergent than necessary. Another problem with hard water is it that forms deposits that can clog pipes and machinery.

D. DISEASE-CAUSING ORGANISMS To see if you have disease causing bacteria in the water, one must perform a coliform count test. A coliform count test measures that number of Escherichia coli bacteria present in the water. Escherichia coli bacteria are disease-causing organisms found in human and animal waste.

II. TREATING DRINKING WATER Water from public and private supplies often needs some treatment to ensure that it is clean and safe to drink. A simple treatment is a filter but a complicated treatment is a public water treatment plant.

A. STEP 1: FILTRATION Def. of filtration: the process of passing water through a series of screens that allows water through but not larger particles. The large particles are trash, leaves, branches and other large objects.

B. STEP 2: COAGULATION In the second step, a chemical called Alum is added to the water to cause sticky globs to form called flocs. Particles that passed through the filtration process stick to the flocs such as particles are mud and bacteria. The sticking to the flocs is called coagulation.

C. STEP 3: SETTLING BASINS The flocs are removed from the water by settling to the bottom of a basin. The top water is pushed through to a second filtration step.

H. TESTING SAMPLES Public health officials regularly test water samples from treatment plants to make sure it is safe. Private owners of wells have to test their water themselves.

I. WATER DISTRIBUTION From a treatment facility, water is pumped to a central pumping station. From the central pumping station, the water is pumped through an underground network of pipes called water mains. Water from water mains branch into smaller pipes that goes to homes and businesses.

Water moves through the pipes via the force of pressure within an enclosed pipe. A community can use a water tower or water tank on top of a hill to pump water to homes instead of a central pumping station. When water is needed from a water tower or water tank, it rushes downhill to the water mains and pipes

D. STEP 4: SECOND FILTRATION The water trickles down through sand or gravel to filter out algae, bacteria, and some chemicals. Water from an aquifer requires less treatment because it naturally flows through rocks and sand to purify the water.

E. STEP 5: CHLORINATION During the third step, chlorine is added to the water to kill any disease-causing organisms.

F. STEP 6: AERATION Air is forced through the purified water to reduce unpleasant odors and tastes. Minerals may also be added to soften the water.

G. STEP 7: ADDITIONAL TREATMENT Sodium or lime may be added to soften hard water. Fluoride is added here to help prevent tooth decay.

H. TESTING SAMPLES Public health officials regularly test water samples from treatment plants to make sure it is safe. Private owners of wells have to test their water themselves.

I. WATER DISTRIBUTION From a treatment facility, water is pumped to a central pumping station. From the central pumping station, the water is pumped through an underground network of pipes called water mains. Water from water mains branch into smaller pipes that goes to homes and businesses.

Water moves through the pipes via the force of pressure within an enclosed pipe. A community can use a water tower or water tank on top of a hill to pump water to homes instead of a central pumping station. When water is needed from a water tower or water tank, it rushes downhill to the water mains and pipes

III. TREATING WASTEWATER Def. of sewage: water that holds different types of waste. Sewage can be cleaned through a wastewater treatment plant (public) or a septic system (private).

A. WASTEWATER TREATMENT PLANTS Household wastewater flows through a network of pipes called sanitary sewers. The sanitary sewers feed to a wastewater treatment plant in order to clean the water so it is safe to return to the environment.

B. SEPTIC SYSTEMS A septic system is a private underground septic tank that stores sewage and wastewater. Bacteria are found in a septic system that breaks down the sewage and wastewater. Sludge and scum are materials that bacteria cannot break through or do so very slowly.

Sludge sinks to the bottom of the septic system it is very dense but scum is very light and it flows on the top of the septic system. Sludge and scum needs to be professionally removed before it starts to build up in the septic system. The remaining water in the septic system filters out small holes into the surrounding soil area. That surrounding soil area is called a leach field. Any waste found in the leach field will break down naturally.