Notes

Hardness in Drinking Water - healthvermont.gov ~ 11 May 2021
Is Hard Water Dangerous to Drink? - mcgill.ca ~ 11 Jan 2019
The Effects Of Drinking Hard Water - culligan.com ~5 Sept 2017
Is Your Water Softener Level Too Soft? - culligan.com ~ 24 Feb 2016

Hardness was originally a measure of the capacity of water to react with soap, where hard water requires more soap to create a lather. Water described as “hard” contains high amounts of naturally occurring dissolved calcium and magnesium. Total hardness is the sum of the calcium and magnesium concentrations, both expressed as calcium carbonate, in milligrams per liter (mg/L). You can determine your water’s hardness based on these concentrations of calcium carbonate:
below 75 mg/L - is generally considered soft
76 to 150 mg/L - moderately hard
151 to 300 mg/L - hard
more than 300 mg/ - very hard
Groundwater that has been in contact with porous rocks containing deposits of minerals like limestone or dolomite will be very hard, while water from glaciers or flowing through igneous rocks is much softer. Studies have generally found hard water to have positive effects on the health of its drinkers. Several studies have reported that calcium and magnesium in drinking water have a dose-dependent protective effect when it comes to cardiovascular disease, rectal cancer, and pancreatic cancer, and that magnesium may help protect against esophageal and ovarian cancer. Studies have shown a relationship between the mineral content of water and eczema or dermatitis in children. However, a 2011 study from the University of Nottingham involving 336 children aged 6 months to 16 years with eczema put that relationship to the test. The researchers installed water softening units in half of the participants’ homes and monitored the children’s eczema over a period of 3 months. Using a standard scoring system, the group that received softened water showed a 20% improvement, while the group that continued with hard water showed a 22% improvement, making it unlikely that hard water is contributing to worsening eczema symptoms. It is estimated that individuals living in hard water areas who drink 2 litres of water a day ingest about 52 mg of magnesium from their water. Individuals with type 2 diabetes often experience hypomagnesemia (low magnesium) as insulin regulation requires magnesium to function. In these people, the extra intake of magnesium through drinking water could be beneficial. One study noted that vegetables cooked in hard water often show an increase in their calcium concentration, as opposed to the decrease seen when they’re cooked in soft water. It is fairly difficult for humans with healthy kidneys to experience hypercalcemia (too much calcium), as any excess calcium is excreted through the kidneys. Similarly, hypermagnesemia is fairly rare, and usually just results in short episodes of diarrhea. The water that runs through your house and in public buildings has varying levels of hardness based on calcium carbonate concentration. The numbers may not mean much if you don’t know what the effects of hard water are. If you have hard water you’ve probably already noticed its effects around your home – dry skin and hair, soap scum, and sluggish appliances. After your water softener is installed, you may begin to notice your skin feeling a bit slippery after a bath or shower. It’s a stark difference from the hard water shower experience, which causes a soapy film to remain after rinsing, resulting in dry skin and weighed-down hair.