A recently released United States Geological Survey (USGS) study shows a high chance of corrosive groundwater in Maryland and 24 other states. Corrosive groundwater can leach harmful substances such as lead or copper from pipes and plumbing fixtures in wells and homes. The large-scale lead poisoning incident in Flint, Michigan, was primarily due to corrosive water running through lead pipes (although in Flint, surface water was the source and not groundwater as covered in this report). As the map below shows, Maryland was found to have potentially corrosive groundwater across almost the entire state.
From the USGS announcement (2016-07-13) on the release of the report:
A new U.S. Geological Survey assessment of more than 20,000 wells nationwide shows that untreated groundwater in 25 states has a high prevalence of being potentially corrosive. The states with the largest percentage of wells with potentially corrosive groundwater are located primarily in the Northeast, the Southeast, and the Northwest. …
Two indicators of potential corrosivity were combined to determine that corrosive groundwater occurs in all 50 states and the District of Columbia. Corrosive groundwater, if untreated, can dissolve lead and other metals from pipes and plumbing fixtures.
“The corrosivity of untreated groundwater is only one of several factors that may affect the quality of household drinking water at the tap,” said Stephen Moulton II, chief, USGS National Water-Quality Program. “Nevertheless, it is an essential factor that should be carefully considered in testing for water quality in both public and private supplies nationwide.”
Public water supplies are regulated by the U.S. EPA, but maintenance, testing and treatment of private water supplies are the sole responsibility of the homeowner. About 44 million people in the U.S. get their drinking water from private wells, yet surveys indicate many homeowners are unaware of some basic testing that should be done to help ensure safe drinking water in the home.
“Fortunately, in most areas of the country and with appropriate safeguards, the majority of homeowners can get good quality drinking water from private wells,” said Moulton. “But this study is a good reminder that prudent, routine testing of the water, including its interaction with the water supply system, is an essential first step so homeowners and their families can confidently drink water from their faucets.”
Naturally corrosive water is not dangerous to consume by itself, however it can cause health-related problems by reacting with pipes and plumbing fixtures in homes. If plumbing materials contain lead or copper, these metals may be leached into the water supply by corrosive water. Signs of corrosive water causing leaching of metals may include bluish-green stains in sinks, metallic taste to water, and small leaks in plumbing fixtures.
Potential sources of lead in homes include:
lead pipes or fittings used in homes built prior to 1930
lead solder used in copper fittings in homes built prior to the late 1980s
“lead-free” brass components, which, in all states, except California, may have contained up to 8 percent lead, prior to 2014
galvanized steel that contained 0.5 to 1.4 percent lead, prior to 2014
A Baltimore Sun editorial (2016-07-14) said the report called into question whether there is sufficient regulation and oversight of well water. The editorial also criticized governments for not adequately protecting water supplies and making the necessary infrastructure investments:
The [USGS] assessment of about 20,000 wells found that half of states face this potential threat, with groundwater samples in Maryland and much of the Northeast and Deep South determined to be corrosive enough to place those areas at “very high” risk. Roughly one of out of six Maryland residents gets their drinking water from a well. …
The report also begs the question: Is the quality of well water sufficiently monitored and regulated? The federal government requires no check for lead or other contaminants in well water, nor does the Maryland Department of the Environment. Some counties may require initial tests for potability in a new well, but none requires follow-up monitoring. …
Ensuring healthy drinking water for all Americans ought to be a high priority, yet — like ensuring quality roads, bridges and other public infrastructure — there’s been a lack of sufficient investment. As a recent survey by the American Water Works Association discovered, as many as 22 million Americans are served their drinking water through lead water lines, part of a chronic problem that would require at least $30 billion more in infrastructure spending.