Drinking water and health - water hardness
Author: Allen Huang 2024-07-06
Table of Contents
China
United States
European Union
World Health Organization
3. Effects of Hard Water on Health and Daily Life
4. How to Test Water Hardness at Home
5. The Best Way to Improve Water Quality
6. Frequently Asked Questions (FAQ)
7. Why Choose an Instant Boiling Water Tap from Xiamen Smart Water Technology
Water hardness refers to the concentration of calcium (Ca²⁺) and magnesium (Mg²⁺) ions in water. These minerals are naturally absorbed as water flows through soil and rock layers. The higher their content, the "harder" the water becomes.
Hardness is usually expressed in milligrams per liter (mg/L) as calcium carbonate (CaCO₃). Water with higher hardness levels can cause scaling in appliances and impact both health and taste.
| Hardness Level | Calcium Carbonate (mg/L) | Description |
|---|---|---|
| 0–60 | Soft water | Smooth taste, gentle on skin and appliances |
| 60–120 | Moderately hard water | Slight mineral taste, minor scale formation |
| 120–180 | Hard water | Noticeable scaling and taste differences |
| 180+ | Very hard water | Heavy scaling, poor soap lather, dry skin |
China
According to China's Drinking Water Hygiene Standard (GB5749-2022), implemented on April 1, 2023:
The total hardness (as CaCO₃) should not exceed 450 mg/L.
Water is classified as follows:
| Class | Hardness (mg/L) | Description |
|---|---|---|
| Class I | ≤ 50 | High-quality water |
| Class II | ≤ 100 | Qualified water |
| Class III | ≤ 150 | Drinkable water |
| Class IV | > 150 | Poor-quality water |
United States
In the U.S., water hardness is commonly measured in grains per gallon (gpg), where 1 gpg = 17.1 mg/L.
| USGS Category | Hardness (gpg) | Equivalent (mg/L) | Description |
|---|---|---|---|
| Soft water | < 1 | < 17.1 | Excellent for drinking |
| Moderately hard | 1–7 | 17.1–120 | Slight mineral presence |
| Hard water | 7–10.5 | 120–180 | Visible scaling |
| Very hard water | > 10.5 | > 180 | Heavy scaling issues |
The U.S. Environmental Protection Agency (EPA) suggests drinking water hardness below 60 mg/L for optimal taste and health.
European Union
The EU Drinking Water Directive defines the following categories:
| Category | Hardness (mg/L) | Description |
|---|---|---|
| Soft | 0–60 | Pleasant taste, gentle on appliances |
| Medium | 60–120 | Acceptable hardness |
| Hard | 120–180 | Requires water softening or filtration |
World Health Organization (WHO)
WHO recommends that suitable drinking water have a hardness level below 170 mg/L, as excessive hardness may affect both health and household use.
Health Concerns:
Prolonged consumption of high-hardness water can impact the cardiovascular, urinary, and nervous systems. It may also contribute to kidney stones due to excess calcium and magnesium intake.
Taste and Cooking:
Hard water often has a metallic or astringent taste, which can affect the flavor of tea, coffee, and food. It also leaves mineral deposits in kettles and pots.
Skin and Hair:
Bathing with hard water can cause dryness and irritation. The mineral film left on skin and hair blocks pores, making it harder for natural oils to moisturize effectively.
Laundry and Cleaning:
Hard water reduces soap efficiency, leaving clothes stiff and dull. Dishes and bathroom fixtures often show white spots or residue from mineral buildup.
Home Appliances:
Scale accumulation in kettles, water heaters, and pipes lowers heating efficiency and increases power consumption. Over time, it can lead to damage and costly maintenance.
You don't always need professional equipment to check your water hardness. Here are three easy ways:
Look Test:
Mix equal amounts of tap water and soapy water, shake well, and observe.
- Lots of foam → soft water
- Little foam + scum → hard water
Taste Test:
Boil your tap water and taste it. A bitter or chalky taste suggests higher hardness levels.
Check Your Appliances:
Yellow or white deposits inside kettles or on faucets are clear signs of hard water.
Installing a water filtration system or instant boiling water tap can effectively reduce hardness and improve water taste.
Xiamen Smart Water Technology Co., Ltd. provides under-sink drinking water systems with advanced filtration to remove calcium and magnesium ions, delivering pure, great-tasting, and safe drinking water for homes and offices.
| Solution | Function | Benefit |
|---|---|---|
| Under-sink water filter | Removes minerals and impurities | Improves taste and reduces scaling |
| Instant boiling water tap | Provides purified hot water instantly | Convenient for tea, coffee, and cooking |
| Water softening system | Reduces calcium & magnesium content | Prevents limescale buildup |
Q1: Is hard water safe to drink?
Yes, but long-term consumption of very hard water may cause health issues and reduce appliance efficiency.
Q2: How can I soften hard water at home?
You can install a water softener or use a reverse osmosis (RO) filtration system under your sink.
Q3: Does boiling water reduce hardness?
Boiling can remove temporary hardness caused by bicarbonates, but it won't eliminate permanent hardness due to calcium or magnesium sulfates.
Q4: Which water is best for drinking-soft or hard?
Moderately soft to medium-hard water (60–120 mg/L) is ideal. It retains essential minerals but avoids excessive buildup.
Xiamen Smart Water Technology Co., Ltd. is a leading instant boiling water tap manufacturer and trusted ODM supplier behind many international drinking water brands.
We specialize in:
- Boiling and chilled filtered water systems
- Under-sink water filtration solutions
- Custom ODM manufacturing for global brands
Partner with us for high-quality, energy-efficient, and health-conscious water systems.
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