Water Quality Series: Metals

What are they and where do they come from?

Metals are substances naturally found in the earth’s crust. Humans have used them extensively throughout history. Metals are so crucial for human civilization that historians have even named entire periods of history after them. Take the Bronze age, for example; this time period was characterized by the heavy use of copper blends for tools, art, and weapons.

Today, we use more metals than ever, resulting in some unintentional environmental impacts. Heavy metals have been found to accumulate in the tissues of living organisms, soils, and eventually, reach our water supply. These metals can enter our drinking water sources by percolating rainwater through soil and rock where it is naturally present. However, higher concentrations and less common metals can come from various human activities such as mining, landfill leaching, agriculture, transportation, and industry (Pedersen).

Health impacts?

Some metals are considered essential nutrients for the body that perform a myriad of tasks to keep us healthy. For example, the saying goes that calcium builds strong bones. In addition, iron is the core component of our blood cells, and sodium balances our bodily fluids while also assisting our nerve cells with signaling (“Precious Metals and Other Important Minerals for Health – Harvard Health”).

These are the metals needed for our bodies to function properly:

• Calcium
• Chromium
• Copper
• Iron
• Magnesium
• Manganese
• Molybdenum
• Potassium
• Sodium
• Zinc

While the metals above are necessary for our bodies, they can have adverse effects when humans are exposed to high concentrations. Other metals not associated to human health can have adverse effects. The list below showcases some common metals found in drinking water, where they come from, and how they impact health.

Lead– Usually from corrosion of plumbing systems in older homes and dated infrastructure. It is especially damaging to children. Lead impacts the brain and nervous system leading to developmental issues, behavior issues, and difficulties with speech. Lead exposure in adults produces hypertension, kidney issues, neurological disorders, muscle pain, and reproductive issues.

Copper– Sourced from corrosion of household plumbing and fixtures. At low levels, copper is considered an essential nutrient. Too much copper can negatively impact your gastrointestinal system, kidneys, and liver.

Arsenic – Naturally occurring in soils and limestone bedrock. Human activities such as mining, agriculture, and industry can contribute to increased concentrations in the environment. Arsenic is a carcinogen, and continued exposure can cause skin lesions, organ issues, cardiovascular disease, and other health problems.

Cadmium – Like arsenic, cadmium is found in soils and limestone. Due to its use in industrial applications and use in galvanized piping, it can also come from corroding pipes, industrial discharge, landfills, and more. Health issues from cadmium impact kidney function and bone density.

Chromium – Mostly discharged due to human activity, chromium is used in metal plating, chemical manufacture, paints, etc. Chromium can cause skin, digestive, and blood issues.

 (“Table of Regulated Drinking Water Contaminants | Ground Water and Drinking Water | US EPA”)

This list is a great place to start if you are testing your well and would like to identify potential household plumbing corrosion or metal contamination.

How can it be treated?

The first step to treatment is to identify the source. To do this you would collect a sample at your well, then another at your tap and compare the results. If you have municipal water, you would compare your consumer confidence report or water quality report from your supplier to samples collected at your tap. Both options allow you to compare influent water quality before and after your plumbing system. In an effort to reduce costs on sampling and laboratory analysis, I suggest starting with water from your tap to identify any problem contaminants first, then work your way to the source.

Suppose you determine that the metal contamination is from your home plumbing. In that case, you can use a neutralization filter, or chemical injection pumps to adjust the ph. pH is important because acidic water has a high corrosion potential. Balancing the pH will decrease the opportunity for metal from your pipes to leach into your water supply. Another option would be to upgrade the metal plumbing in your house to plastic (PVC) pipes (Ling et al.). This option has a high upfront cost but little continued maintenance.

If you find that the metals are coming from your groundwater source, you can treat your water with several existing technologies:  

Reverse Osmosis

Reverse osmosis uses pressure to push water through a superfine membrane allowing clean water to pass and holding contaminants behind. This system needs relatively clean water as a source, so it is commonly sold as a multi-stage filtering unit using reverse osmosis as one of the stages. These multi-stage systems are handy for treating metals and a spectrum of other contaminants like nitrate and sulfate. There are also versatile installation options. Smaller systems can be installed behind the refrigerator or under a sink, and larger systems can be installed to treat the entire house. The downsides of this system include increased water use, regular filter replacement, and treatment volume limitations.

Distillation

Distillation is a method that heats water to its boiling point and then allows it to cool and condense into a separate container. This process removes many contaminants, and the heat kills bacteria. These systems are primarily used as stand-alone countertop devices and not for whole-house treatment. Some see this as a disadvantage and as an advantage to others. No plumbers or technicians are needed to purchase, install, and operate this system. Many folks travel with them to get relatively consistent water quality wherever they go. Disadvantages of this system are limited treatment volumes (produces only a couple gallons a day), increased electricity use, and initial cost.

Redox Media

When combined with activated carbon, redox media uses oxidation-reduction reactions to give or take electrons to and from metals. This process causes them to fall out of solution and become a solid that gets trapped within the filter media. The system then needs to be periodically backflushed to remove these contaminants.

In conclusion..

Metal contamination in your drinking water supply is nothing to take lightly.

Changes in groundwater quality from new development, industrial activity, and even some natural processes are all factors that contribute to the presence of these substances in your source water.

The general suggestion is to review your water quality annually or if someone in your home is pregnant, nursing, or unexplainably ill.  If you are concerned about metals in your water, you can review your consumer confidence report provided by your municipal water supplier. If you have well water, you may want to get your water tested by a laboratory.

Curious about laboratory options? Feel free to contact your local extension office or Department of Health, and they will be happy to help.

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Works Cited

Ling, Erin, et al. Virginia Household Water Quality Program: Heavy Metals in Household Water. Virginia Cooperative Extension, Nov. 2011.

Pedersen, TL. “Metals in Your Drinking Water.” EXTOXNET – The EXtension TOXicology NETwork, UCD EXTOXNET FAQ Team, 1 June 1997, http://extoxnet.orst.edu/faqs/safedrink/metals.htm.

“Precious Metals and Other Important Minerals for Health – Harvard Health.” Harvard Health, Harvard Health Publishing, 1 July 2018, https://www.health.harvard.edu/staying-healthy/precious-metals-and-other-important-minerals-for-health.

“Table of Regulated Drinking Water Contaminants | Ground Water and Drinking Water | US EPA.” UNT Web Archive – Table of Regulated Drinking Water Contaminants, Environmental Protection Agency, 4 Oct. 2016, https://webarchive.library.unt.edu/web/20161224233827/https://www.epa.gov/ground-water-and-drinking-water/table-regulated-drinking-water-contaminants.