Defining Water Hardness and Calcium Levels
Water hardness is determined by the concentration of dissolved minerals, predominantly calcium and magnesium. When rainwater travels through the earth, it comes into contact with rock formations like limestone and gypsum, dissolving these minerals and carrying them into the water supply. The higher the mineral concentration, the harder the water. While there is no single, globally mandated health standard for hardness in drinking water, several organizations provide classifications to help consumers understand the quality of their water supply.
Common Hardness Scales:
- US Geological Survey (USGS): Defines soft water as 0–60 mg/L, moderately hard as 61–120 mg/L, hard as 121–180 mg/L, and very hard as over 180 mg/L.
- Vermont Department of Health: Classifies water as hard at 151–300 mg/L and very hard at over 300 mg/L, noting that levels above 150 mg/L are considered a nuisance.
- World Health Organization (WHO): Notes that hardness levels above 200 mg/L as calcium carbonate will produce scaling.
For general purposes, a reading of 121 mg/L (ppm) or higher is widely considered hard or high calcium in water and will begin to present noticeable issues in the home. This is because calcium carbonate concentrations lead to the formation of limescale, particularly when the water is heated.
Signs of High Calcium in Your Water
Beyond a formal test, your home will often provide a number of indicators that you have high calcium levels in your water. Learning to recognize these signs can help you diagnose the problem early and prevent more significant damage.
Inefficient Soaps and Detergents
- Poor lathering: Hard water minerals react with soap, forming a sticky scum rather than a rich lather.
- Dull laundry: Clothes washed in hard water can feel stiff, rough, and look dingy or faded over time.
- Soap scum residue: An excessive amount of residue is left on sinks, bathtubs, and showers, requiring more effort to clean.
Limescale Buildup and Appliance Damage
- White, chalky deposits: You will notice white or off-white mineral deposits (limescale) around faucets, showerheads, and on tile surfaces.
- Spotted glassware: Clean dishes and glassware show white, cloudy spots after washing, even in a dishwasher.
- Reduced appliance efficiency: Limescale can build up inside hot water heaters, dishwashers, and coffee makers, reducing their efficiency and lifespan. In water heaters, this scale acts as an insulator, forcing the unit to use more energy to heat the water.
Skin and Hair Problems
- Dry, itchy skin: The mineral residue left behind by hard water can clog pores and strip the skin of its natural oils, leading to dryness and irritation. This can be especially problematic for people with conditions like eczema.
- Dull hair: High calcium levels can make hair feel brittle and look lifeless because the minerals prevent shampoo from rinsing out completely.
How to Measure Your Water's Hardness
If you suspect high calcium levels, several methods can provide an accurate reading of your water's hardness:
- DIY Test Kits: Inexpensive test strips or liquid reagent kits are available at home improvement stores. These provide a quick color-coded result indicating the hardness level.
- Professional Lab Testing: For the most precise analysis, you can send a water sample to a certified laboratory. A professional test will provide a detailed report on mineral content.
- Municipal Water Report: Your local water utility company is often required to provide an annual water quality report that details the hardness levels in your area.
Hard Water Classification Comparison Table
| Classification | USGS (mg/L or ppm) | Vermont Dept. of Health (mg/L) | Health Canada (mg/L) | Electrostore Online (ppm) |
|---|---|---|---|---|
| Soft | 0–60 | <75 | <60 | <50 |
| Moderately Soft | N/A | N/A | 60–120 (Medium Hard) | 51–100 |
| Slightly Hard | 61–120 (Moderately Hard) | 76–150 (Moderately Hard) | N/A | 101–150 |
| Hard | 121–180 | 151–300 | 120–180 | 201–275 |
| Very Hard | >180 | >300 | >180 | 276–350 |
| Aggressively Hard | N/A | N/A | N/A | >350 |
Solutions for High Calcium in Water
Once you have confirmed that your water has high calcium levels, there are several treatment options available. The best solution depends on your specific needs and budget.
Water Softeners (Ion Exchange)
This is the most common and effective method for removing hardness minerals. A water softener uses an ion exchange process, replacing the calcium and magnesium ions with sodium or potassium ions.
Pros:
- Effective for treating the entire home's water supply.
- Protects plumbing and appliances from scale buildup.
- Improves soap and detergent performance.
- Provides softer-feeling water that is kinder to skin and hair.
Cons:
- Increases sodium levels in the water, which may be a concern for those on restricted diets.
- Requires regular replenishment of salt or potassium pellets.
- Can be a significant upfront investment.
Reverse Osmosis (RO) Systems
An RO system forces water through a semipermeable membrane that removes dissolved minerals, including calcium. While highly effective at purifying water, it's typically used for drinking water at a single tap rather than for the whole house.
Scale Inhibitors and Conditioners
These systems do not remove calcium but prevent it from forming scale. They can be a lower-maintenance and less expensive alternative to a traditional water softener for some applications, though their effectiveness can vary.
Alternative Methods
While not as robust, some temporary or small-scale solutions exist:
- Boiling: Can reduce temporary hardness caused by bicarbonates, but is not effective for permanent hardness from sulfates or chlorides.
- Vinegar: Acetic acid can dissolve limescale for cleaning fixtures and appliances, but it's not a solution for treating your entire water supply.
Is High Calcium Water a Health Concern?
For most people, high calcium in water is not a health risk and can even contribute to daily mineral intake. However, some individuals may experience gastrointestinal issues. Studies have also linked high calcium intake from water to a higher risk of kidney stones in some people. If you have pre-existing conditions or concerns, it is always best to consult with a healthcare professional.
It is important not to confuse hypercalcemia, a medical condition involving dangerously high levels of calcium in the blood, with drinking hard water. The amount of calcium from hard water is typically a minor dietary contribution compared to food sources like dairy.
Conclusion
Understanding what is considered high calcium in water is the first step toward addressing the issues of hard water. Levels starting around 121 mg/L (or 7.1 grains per gallon) can cause aesthetic and maintenance problems, with very hard water (over 180 mg/L) presenting more severe scaling and appliance damage. By recognizing the signs, testing your water, and considering effective treatment options like a water softener, you can protect your home, extend the life of your appliances, and enjoy softer, more manageable water. For more information on water quality testing, you can refer to the US Geological Survey's Water Science School.
