The US Environmental Protection Agency (EPA) sets the standards for drinking water in cooperation with local water system organizations and other agencies within the community. These standards are published in the Code of Federal Regulations. As new analytical methods are developed, scientific information is produced and new priorities are made to counter potential health hazards from contaminants.
The EPA takes into account many issues and factors when setting the standard for drinking water. The calculation of pH is one such detail that measures the active acidity of the water. The pH is important to control pipe corrosion and taste issues for the water supply. Recommended pH is a range from 6.5 to 8.5.
The presence of a harmful chemical or chemicals in the environment, the level of human exposure, potential health risk assessment and the economic effect of water treatment costs are all also taken into consideration.
Fresh water from our aquifer typically contains minerals that control the alkalinity and hardness of our water. These minerals are the source of common elements (ions) including magnesium, calcium, sulfate and carbonates. Such ions together with salt and potassium account for roughly 95% of the total dissolved solids (TDS) found in fresh water. Drinking water should not contain more than 500 mg/L of TDS. High TDS water may cause deposits and/or staining as well as a salty taste present in the water. Nearly 40% of the water delivered to homes in urban areas by community water systems eventually empties into the sewer system, where it is then treated in a waste water treatment plant. However, community water treatment water supplies are usually about 1.5 times higher in TDS than its original source. Within this procedure, waste water treatment removes most pathogens, but does not remove all traces of organic chemicals. Reclaimed waste water is considered to be safe for irrigation but requires treatment in order to be consumed as drinking water.
The National Primary Drinking Water Standards (NPDWS) publishes a list of Maximum Contaminant Levels (MCL) that community water systems must follow. Contaminants on the list are known to be a risk to human health and/or the environment if found in concentrations higher than their MCL. The EPA has also formed National Secondary Drinking Water Standards (NSDWS) to assist community water systems in managing their drinking water for aesthetic reasons, including taste, color and odor. Water utilities control the levels of these contaminants in order to prevent tap water odor and taste- related issues.
Primary contaminants regulated under the NPDWS are divided into six groups:
Inorganic contaminants (arsenic and lead)
Organic chemical contaminants (insecticides, herbicides and industrial solvents like trichloroethylene or TCE)
Water disinfectants (chlorine and chloramines)
Disinfection by-products (chloroform)
Microorganisms (Giardia and intestinal viruses)
The most common elements found in Arizona water in concentrates above drinking water standards are fluoride, arsenic, gross alpha radiation and nitrate. Nitrate contamination is due to either agricultural practices or failing septic systems. Ammonium and phosphorus contamination is also linked to septic sewage problems. Fluoride contamination is most commonly caused by confined aquifers concentrated from volcanic materials and some sedimentary rocks.
Human-made pollutants like agricultural pesticides, industrial solvents, fuel additives, petroleum products, plastics and many other chemicals are present everywhere in our environment due to their extensive use in modern society. Organic matter can also play a huge role in water color, odor and foaming in water supplies. This matter is derived from vegetation present within the water source.
Higher levels of other naturally occurring elements have been found in water across Arizona. For example, naturally occurring hexavalent chromium, known to cause cancer, has been found in Paradise Valley, north of Phoenix. Iron is found in almost all groundwater and is the cause of iron-bacterial fouling in wells.
Contaminated groundwater represents half of the outbreak of waterborne disease cases reported every year. Waterborne pathogens originating from leaking sewer lines, septic systems or improperly protected wellheads that drain water into the aquifer along the outer well casing are the cause. If enough nutrients are available for survival, certain bacteria are liable to form bio-films within the well walls. Iron bacteria live in water concentrates high in naturally dissolved iron. This bacteria can cause plugging of the pores in the aquifer and openings of the well screen. The effect of this can reduce well yield by 75% within a year.
Your water supply may be a health risk if any of these contaminants exceeds MCL standards and should be treated immediately to avoid health risk.