Water Science: Hard Water Deep Dive

Water Science: Hard Water Deep Dive

Published by Dr. Mahika Weerasekare Ph.D on 6th Apr 2021

You may know the basics of hard water, but what about a deeper understanding of not just hard water but also what our system does to stop it? If you’re interested in a deeper look, this is the right place for you. Let’s discuss how we think about hard water, what it really is, and how different treatment methods work at a chemical level.

Traditionally, hard water has been measured by how well soap reacts with water. If water is hard, more soap is required to form a lather but chemically, hard water contains higher amounts of calcium and magnesium ions. Water naturally absorbs these minerals from the Earth as it seeps through soil, flows over rocks, and courses down riverbeds. Not surprisingly, the ratio of minerals in hard water mirrors the ratio found in the Earth’s crust: 67% of water hardness comes from calcium and 37% from magnesium 1.

As water dries or evaporates, the minerals in hard water, especially calcium, bound to carbonate form calcium carbonate deposits that are visible as white spots on freshly washed glass and flatware, faucets and other fixtures. Initially, these deposits are simply an unsightly, but benign, nuisance. Over time, as more calcium-carbonate settles, these unsightly mineral deposits compound and form hardened scale. Scale can build up and destroy water heaters and boilers, clog showerheads and faucets, and reduce the lifespan of appliances like dishwashers and steamers.

What are the Benefits of Hard Water?

Take a look at the nutrition label on your favorite snack. Do you see calcium and magnesium on there? (If not, it may be time to find a new favorite snack!) Calcium and magnesium are essential nutrients and inadequate consumption of either can result in adverse health effects. The World Health Organization (WHO) cites several studies that find consuming hard water is beneficial to human health 2. These studies have found no adverse health effects associated with the consumption of hard water.

In addition to supplying essential nutrients, the same studies suggest there are tangible benefits from consuming hard water that are linked to the relatively low corrosivity of hard water. There is a small amount of oxygen (O2) that we all need to live dissolved in water and the oxygen is corrosive when exposed to metals and other surfaces. The minerals in hard water work as a shield to keep the corrosive oxygen in water away from surfaces. When you remove those minerals through artificial water softening (think ion-exchange softeners), there is nothing protecting surfaces from oxygen and the water turns corrosive, increasing your exposure to harmful metals extracted from pipes and fixtures.

How do Traditional Water Softeners Work?

So how do you treat hard water? Traditional water softening methods work by removing the natural minerals from hard water. The most common method of treating hard water, ion-exchange water softening, replaces the beneficial calcium and magnesium in your water with sodium or potassium. Reverse osmosis (RO) is another method of removing minerals by forcing hard water through a semipermeable membrane. The WHO actually discourages the use of RO for drinking water as the water is so devoid of minerals it can absorb minerals from the human body after consumption.

What are the Environmental Impacts of these Traditional Methods?

Water and our Planet

Fresh water is a dwindling commodity as freshwater sources across the United States are increasingly contaminated with salt. For instance, in New Mexico over 75% of groundwater is too saline for use without treatment 3.

Neither method can be considered environmentally friendly as both ion-exchange and RO water treatment methods waste a significant amount of water and degrade the quality of fresh water supplies. For every gallon of drinking water produced, an RO system releases gallons of water with high mineral content into the environment. Ion-exchange systems are even less environmentally friendly. During the regeneration process they release chloride (salt) into the environment. Chloride was a major contributor to the Flint water crisis 4.

Is it Possible to keep Beneficial Minerals in Water and Stop Scale from Forming?

Yes, it is very possible. There are now several new methods for treating hard water that allow water to retain its beneficial minerals. Unfortunately, many of these methods only change the physical properties of minerals and are temporary, easily reversing over time.

NuvoH2O’s CitraCharge actually effects the chemical bonding of scale forming calcium ions by using a natural chelator, which is a more permanent and less reversible way of avoiding scale buildup.

What is a Chelator?

You have likely encountered chelators every day without knowing it. Most cleaning products available today, be it soap, detergent, or shampoo, contain added agents called chelators. Chelators improve the function of the soap by keeping minerals away from the active cleaning agent, improving the lathering ability and cleaning power of the soap (remember the traditional measure of hard water).

Citrate, the active ingredient in NuvoH2O’s CitraCharge, is one such chelator. Citrate is a natural chelator and is actually the only safe and biodegradable chelator currently in use. Like the artificial chelators in soap, citrate (think citrus fruit) keeps minerals away from your pipes and fixtures, preventing scale build up.

How does NuvoH2O’s CitraCharge Prevent Hard Water Scale?

Calcium carbonate is the principal component of hard water deposits and scale, if you can eliminate calcium carbonate you eliminate hard water scale. Ion-exchange systems eliminate calcium carbonate by substituting the calcium with sodium or potassium while NuvoH2O’s CitraCharge works by substituting the carbonate with a small amount of citrate(40 times less citrate per gallon than a glass of orange juice) to disrupt the formation of calcium carbonate. The citrate works to prevent and remove scale in two ways:

First, nature loves symmetry, and hard water scale is no different. Calcium carbonate forms organized molecular structures, like the image to the right, to create scale. Citrate displaces the carbonate ions in scale, destabilizing the chemical structure, causing it to collapse. Even displacing just a few carbonate ions is enough to disrupt the formation of hardened, calcified scale.

Next, altering the pH of the water increases the solubility of the carbonate ions in the water. Increasing the solubility means minerals are more likely to remain in the water and not settle out of water onto surfaces such as pipes, fixtures, and appliances.

Both actions even dislodge deposited minerals, allowing water to wash away mineral buildup.

Additionally, the citrate is both naturally occurring and biodegradable. It won’t harm you or the environment. Unlike other treatment methods, no water is wasted while operating a NuvoH2O system and no salts or pollutants are released into wastewater.

What we can Learn From This

As we can see, there are many benefits to the calcium and magnesium in our drinking water, if only you can keep it from forming scale. Traditional systems like Ion exchange or newer methods like Reverse Osmosis completely remove the calcium and magnesium while the NuvoH2O system keeps those valuable minerals and has no negative environmental impacts.

To learn more, feel free to visit our Product pages or the How It Works pages.


1 http://ocean.stanford.edu/courses/bomc/chem/lecture_12.pdf

2 WHO/HSE/WSH/10.01/10/REV/1

3 https://www.usgs.gov/special-topic/water-science-school/science/saline-water-and-salinity?qt-science_center_objects=0#qt-science_center_objects

4 https://www.acs.org/content/acs/en/education/resources/highschool/chemmatters/past-issues/2016-2017/december-2016/flint-water-crisis.html

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