Hard water
Hard water is defined as water that contains a higher concentration of dissolved minerals, primarily calcium and magnesium, compared to soft water, which has minimal mineral content. The hardness of water can vary significantly based on geographic location, as it depends on the minerals present in the soil and rock through which the water flows. Water hardness is measured in grains per gallon, with ranges classifying water as soft, moderately hard, hard, or very hard.
While hard water can create challenges for households and industries—such as mineral buildup on plumbing and appliances, reduced effectiveness of detergents, and unwanted water spots on dishes—it is generally considered safe for consumption. The minerals in hard water can even provide health benefits, such as additional calcium intake. However, individuals with specific health issues, particularly those affecting kidney function, may need to monitor their intake of hard water.
To mitigate the effects of hard water, various softening methods are available, including chemical treatments used by industries and household water softeners that replace calcium with sodium ions. Despite their benefits, these softening systems may not be suitable for everyone, especially those with sodium sensitivities. Overall, while hard water presents some practical inconveniences, it does not pose significant health risks for the average person.
Subject Terms
Hard water
Hard water is water that contains a higher-than-normal amount of dissolved minerals per gallon. The two main minerals associated with water hardness are calcium and magnesium, but other minerals can also cause hard water. The hardness of water varies from place to place and depends on the minerals present in the ground where the water originates. Water that contains very few of these minerals is considered soft water.
Causes
The hardness of water is measured in grains (of dissolved minerals) per gallon (GPG). Ranges include the following:
- Soft = 0 to 3.5 GPG
- Moderate = 3.5 to 7.0 GPG
- Hard = 7.0 to 10.5 GPG
- Very hard = 10.5 GPG or more
Dissolved calcium and magnesium are the most common sources of water hardness, but metal minerals such as iron, zinc, aluminum, barium, strontium, and manganese can cause hard water, too. These minerals are naturally present in rocks and soil. Their ions, or electrically charged atoms, transfer into water as it percolates, or slowly trickles, through the ground. Calcium usually comes from limestone while magnesium often comes from dolomite. Groundwater, which is closer to the mineral source, is generally harder than surface water.
Effects
Hard water can have significant effects on industry, institutions, and individual households. It tends to leave mineral deposits on everything it touches, including machinery, appliances, plumbing, and household surfaces, such as shower walls. These mineral deposits—known as scale—build up over time, reducing the effectiveness of machinery and appliances that use large amounts of water, especially those that involve the use of hot water, such as industrial water boilers, hot water heaters, and dishwashers. Many home water heaters suffer diminished effectiveness followed by premature breakdown because of hard water mineral deposits. Plumbing pipes also may become clogged with mineral deposits, which can cause blockages and breakage.
Similar deposits are left on items washed with hard water. Clothing washed in hard water may appear dingy and wear out faster while dishes may have water spots and rings. Hard water requires greater quantities of detergent and soap to produce satisfactory results, which leads to the formation of soap scum on sinks, tubs, and shower curtains. In addition, the combination of extra detergent and minerals in the water can leave behind a dulling film on hair and skin washed with hard water.
Health Impacts
According to the World Health Organization (WHO), no significant negative health results are associated with hard water. WHO and other health experts state that the minerals in hard water actually have a beneficial effect by providing a supplemental source of calcium. However, the minerals can have adverse effects on individuals who already have health issues. For example, people with kidney issues that affect how the body processes minerals may develop levels of magnesium that are too high when consuming hard water.
Studies on the effects of hard water on cardiac health, cancer, cerebrovascular health, and several other health conditions have not found any negative connection between consuming hard water and an increase in these conditions. Some studies actually have shown a slight inverse relationship, meaning that people who consume hard water are slightly less likely to have issues related to these conditions. One study estimated that 4.5 million deaths from heart attacks and strokes could be avoided if more people ingested hard water. The study suggests that the addition of magnesium to water sources and to products that contain water, such as bottled beverages, could reduce deaths from heart conditions and stroke around the world.
One adverse condition that may be related to hard water is a form of skin infection that results from bacteria. Some evidence indicates that this infection can be prompted by bacteria trapped in skin pores by the soapy film left after bathing in hard water.
Reducing Hardness
While water hardness poses few, if any, health risks, its tendency to damage machinery and appliances and to leave behind annoying and difficult-to-clean deposits leads many to seek options for softening water. Large industries and municipalities often employ the lime-soda process, which treats hard water with a combination of soda ash and slaked lime. The treatment causes calcium and magnesium to precipitate out of the water as a solid that can be collected and removed.
Household water softening systems also are available. These use an ion exchanger filled with plastic beads that are charged with sodium ions. The exchanger switches the calcium ions for sodium ions, which softens the water. However, these systems have some drawbacks. They can be expensive to purchase and install. They have to be recharged with the appropriate ions to maintain their effectiveness, which adds to the cost and labor involved. In addition, people who have health conditions that are sensitive to sodium, such as high blood pressure, may suffer adverse effects if they drink water treated by a water softener. The increased quantity of sodium present also means that softened water should not be used to water plants, lawns, or gardens.
The use of softened water, however, will result in softer clothes, cleaner dishes, and longer-lasting appliances. For this reason, some people soften their water but continue to use hard water for drinking and cooking.
Bibliography
Blank, Sarah, and Timothy Ellis. "Is Hard Water Bad for You? Two Water Quality Engineers Explain the Potential Benefits and Pitfalls That Come with Having Hard Water." The Conversation, 20 May 2024, theconversation.com/is-hard-water-bad-for-you-2-water-quality-engineers-explain-the-potential-benefits-and-pitfalls-that-come-with-having-hard-water-223408. Accessed 21 Nov. 2024.
Casiday, Rachel, and Regina Frey. "Water Hardness." Department of Chemistry, Washington University. Washington University in St. Louis. Web. 12 Feb. 2016. http://www.chemistry.wustl.edu/~edudev/LabTutorials/CourseTutorials/bb/Water/FreshWater/hardness.html
"Hard Water." ExToxNet. University of California-Davis, Oregon State University, Michigan State University, Cornell University, and the University of Idaho, June 1997. Web. 12 Feb. 2016. http://extoxnet.orst.edu/faqs/safedrink/hard.htm
"Hard Water." Utah Water Quality. Utah State University. Web. 12 Feb. 2016. http://extension.usu.edu/waterquality/htm/whats-in-your-water/hardwater
"Hard Water—To Soften or Not to Soften." College of Agriculture, Food and Environment. University of Kentucky. Web. 12 Feb. 2016. http://www2.ca.uky.edu/agc/pubs/ip/ip7/ip7.htm
Rosanoff, Andrea. "The High Heart Health Value of Drinking-Water Magnesium." Medical Hypotheses81.6.Elsevier, Dec. 2013: 1063–1065. Web. 12 Feb. 2016. http://www.sciencedirect.com/science/article/pii/S0306987713004763
Sengupta, Pallav. "Potential Health Impacts of Hard Water." International Journal of Preventive Medicine4.8.Aug. 2013: 866–875. Web. 12 Feb. 2016. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3775162/
"Water Hardness." USGS Water Science School. US Geological Society. Web. 12 Feb. 2016. https://water.usgs.gov/edu/hardness.html