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What is Water Hardness… and Why Should I Care?

by Mark Timmons June 11, 2024 0 Comments

Hard water is not what water becomes when it freezes. Let’s get that out of the way right now. Of course, that is a poor attempt at humor and it is available to you at no extra charge, but I digress. In scientific terms, water hardness is generally the amount of dissolved calcium and magnesium in water. Hardness is caused by compounds of calcium and magnesium, and by various other metals. General guidelines for the classification of water are as follows:

• 0 to 60 mg/L (milligrams per liter) as calcium carbonate is classified as soft.
• 61 to 120 mg/L as moderately hard.
• 121 to 180 mg/L as hard.
• and more than 180 mg/L as very hard.


US Geological Survey and USEPA

Water systems relying on groundwater sources are particularly concerned about water hardness. As water traverses through soil and rock, it naturally absorbs trace amounts of minerals, such as calcium and magnesium, entering the groundwater reservoir. Consequently, households may receive hard water if these minerals are prevalent in the surrounding soil near a water supply well.

The degree of water hardness varies across the United States. In regions where water is notably hard (refer to the accompanying map above), industries may need to invest in water-softening measures to protect their equipment from potential damage. Furthermore, hard water can accelerate the deterioration of fabrics and clothing, prompting jests about whether students in areas with hard water are inadvertently staying ahead of fashion trends due to their garments wearing out more quickly. Of course, the resulting damage to pipes, water heaters, faucets, dishwashers, washing machines, and anything water touches, is very tangible and expensive. 

Understanding Hardness Measurements

In the water softening industry, water treatment companies and their employees frequently refer to hardness using the term “grains per gallon” (or gpg) instead of

milligrams per liter (mg/l). To put this all in perspective, 12 inches make one foot. These are just two methods of describing the same distance. The same applies to grains per gallon, milligrams per liter, and parts per million (ppm). Just as there are 12 inches in 1 foot, there are 17.1 mg/l (or ppm) in 1 grain per gallon. Therefore water that is 256 mg/l is approximately 15 gpg (256 divided by 17.1).

To give even more context to water hardness, mg/l and gpg are both weight measurements. It takes 7,000 grains or 119,700 mg/l to make a pound. A pound of what? As we mentioned earlier, hard water is primarily composed of calcium and magnesium or, to put it bluntly, it is simply “dissolved rock.” Let’s do a simple calculation of a family of four with water that is 20 gpg (342 mg/l). It is generally true that the average person uses 75 to 100 gallons per day. This includes showering, cooking, drinking washing hands, flushing toilets, cleaning, and drinking. So a family of four would expect to use 300-400 gallons a day. Let’s say the number is 350 for the sake of this exercise. So, first, we take the number of gallons (350) and multiply it by 20 gpg. (350 times 20 equals 7,000 grains), which is exactly one pound of dissolved rock. This happens every day. In a year, you would have had 365 pounds of dissolved rock pass through your home’s plumbing system and wreak havoc on pipes, water heaters, appliances, and faucets to say nothing about spots, streaks, and scum on dishes and glasses, showers, and everything that water touches.

The Impact of Hard Water

Have you ever unloaded the dishwasher only to find your sparkling glasses marred by unsightly spots and films? Fear not, for this is merely the residue left behind by the relentless force of hard water. While not harmful, it's certainly an unwelcome sight for many who are meticulous about their dishware. The specter of hard water haunts industrial giants and humble homeowners alike, raising concerns about its relentless grip on our daily lives. When hard water meets the fiery embrace of a water heater, it gives birth to solid deposits of calcium carbonate, notorious for wreaking havoc. These insidious scales shorten the lifespan of our cherished appliances, inflate heating expenses, sabotage the efficiency of both gas and electric water heaters, and maliciously clog pipes with steadfast determination.

Even the sanctum of morning rituals, the beloved coffee maker, falls victim to the insidious mineral buildup. Thus, some resort to the acidic embrace of vinegar to wage war against these calcified invaders.  Vinegar's acidity deftly dissolves mineral particles through a chemical ballet, rendering them susceptible to the seductive dance of water's polar charges, ultimately washing them away in a cleansing torrent. Yet, amidst the chaos and turmoil, hard water offers a glimmer of redemption. The World Health Organization, that stalwart guardian of our well-being, reminds us that hard water isn't entirely devoid of virtues. In its mineral-laden embrace, hard water bestows us the gift of essential nutrients, calcium, and magnesium, a boon to our health, especially for those teetering on the brink of deficiency.

That is all well and good until one realizes that water is not a significant source of minerals unless you think drinking a bathtub full of water a day is a good idea. This is why it’s important to maintain a nutritious diet and not only rely on drinking water to supply you with vitamins and minerals. 

Choosing a Water Softening Solution

So, if you have water that is over 180 mg/l or 10.5 gpg, you will likely want to treat that water with a water softener or a salt-free alternative. A water softener works by removing the calcium and magnesium and replacing it with sodium, whereas a salt free conditioner works by “tying up” the calcium and magnesium so that it cannot stick to pipes and appliances. You can read more about these two solutions in one of our recent Salt-Free Conditioners Vs. Salt Water Softeners article. . 

Deciphering whether water possesses the audacious charm of softness or the unyielding temperament of hardness is no mere glance-and-guess affair. Oh no, dear seeker of aqueous enlightenment, for water keeps its secrets well. Yet fear not, for there are subtle cues, hints if you will, that may betray its true nature.

Recognizing the Signs of Hard Water

Behold, the telltale signs of hard water:

• Firstly, a lingering film upon your hands post ablution, a testament to the soap's
reluctant tango with calcium, birthing the notorious soap scum. Should you find
yourself engaged in an extended rinse, know that hardness lurks.

• Secondly, witness the blemished visage of your once gleaming glasses and
silverware emerging from the cleansing chamber of your dishwasher. Fear not, for
these spots are but deposits of calcium carbonate, a calling card of the unyielding

• Thirdly, observe the tragic tale of your garments, speckled with mineral stains
post-laundering. Alas, the harsh embrace of hard water accelerates their demise, a lamentable consequence of its unforgiving temperament.

• Lastly, heed the whispered cries of your abode, as the water pressure dwindles,
choked by the clandestine formations within the labyrinth of your pipes, a silent
testament to the tyranny of hardness.

Yet, amidst this aquatic drama, there exists a contrasting narrative, a tale of softness:

• Rejoice, for in the realm of soft water, a bountiful lather awaits, an effervescent
embrace in the choreography of cleansing.

• Witness the garments emerge unscathed, devoid of mineral stains, their threads
spared the ravages of wear and tear.

• Behold the symphony of water pressure, a harmonious flow coursing through the veins of your home, unimpeded by mineral deposits
• And should you dare to indulge, a whisper of sodium upon your palate, a subtle
reminder of water's softened essence, though often imperceptible to the discerning palate. (Full Disclosure: I do not like the taste of soft water so I only drink Reverse Osmosis water whether it is from my tap or if I am on the road, I only partake of Aquafina).

Thus, dear seeker, armed with these subtle revelations, venture forth and unlock the mysteries of water, whether hard or soft, with the grace and panache befitting a connoisseur of liquid alchemy.


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