It’s been a generation since the U.S. Congress passed the Safe Drinking Water Act, which empowered the Environmental Protection Agency to promulgate and enforce comprehensive quality standards. While the law has helped to ensure one of the safest overall drinking water supplies in the world, what’s true nationwide isn’t necessarily true of what’s coming out of your tap. The condition of the source water, plus the methods used to treat it, can cause variations in water quality from place to place.

That’s not all. U.S. laws and regulations don’t cover single-family homes served by private water wells, as is common in most rural and semi-rural regions. About one out of every eight homes has a well. Even where private groundwater or public water is of superior quality, contamination can be introduced by home plumbing systems, also not subject to regulation.

Water for public supplies comes from two principal sources: Above ground, such as rivers, lakes and reservoirs, which are fed by the runoff from rainfall or snowmelt; and under ground, in which reservoirs, called aquifers, are slowly recharged by surface water percolating through sand, soil and rock.

Whether above ground or below it, water dissolves naturally occurring minerals that come into contact with it. It’s also vulnerable to environmental substances resulting from human activity or animals in the general vicinity. Dissolved minerals such as calcium, iron and manganese cause what is commonly known as hard water. Development, industry, agricultural and numerous other land uses also can contribute to contamination. Not only that, water can pick up traces of naturally occurring radiation from the rocks around which it passes.

 

Contamination takes many forms, including:

•  Microbes such as bacteria and viruses. Sources for microbes include treatment plants, septic systems, livestock and wildlife.
•  Pesticides and herbicides used in both residential and agricultural applications.
•  Organic chemicals whose sources can include storm-water runoff, septic systems and synthetics, such as gasoline and other refined petroleum products stored in underground tanks.
•  Inorganic compounds such as salts or metals. These can occur naturally; they may also result from storm runoff, wastewater discharges, and mining and farming operations. Corroding copper pipes inside homes also introduce traces of the metal into the water.

It’s important to understand how EPA guards water quality:

•  Public water supplies may be provided by municipal utilities, private companies, or even cooperatives and neighborhood associations. EPA regulates all of these entities as community water systems regardless of whether they’re operated for profit or not. Community water systems serve roughly seven out of eight U.S. homes.
•  Among regulated systems, EPA has established maximum contaminant levels for each of more than 150 substances that can appear in public water supplies. The agency also sets minimum standards for regular quality testing and for reporting the results of those tests.

Isn’t it EPA’s job to make sure water is free of contamination? The answer is no. The agency’s standards are designed to ensure that public water is pure enough to be completely safe for consumption by healthy individuals. Stricter regulation likely would result in skyrocketing water bills.

What can a concerned person do?

If you’re served by a public system, it’s required to furnish the most recent testing reports to users on request. Most large systems analyze water quality several times a year, and summarize their findings in an annual report. Many such reports offer both the technical details from the tests and a non-technical written analysis of water quality. Some utilities will mail you a copy; others may offer it for public inspection or copying in their own offices, at town or city halls, and at public libraries. Read the report, and ask questions if you’re not sure about anything you see in it.

Those whose homes have a private well may wish to see the entry Water well for more information. Nearly 30 million Americans live in homes served by private wells.

Regardless of water supply, more than two out of five American families choose some form of private water treatment. This can range from a simple, $20 water-filtration pitcher that removes some contamination to a sophisticated system costing thousands installed as part of house plumbing that removes much more. Some form of water filtration may be necessary for households in which one or more residents have a compromised immune system.