Hardness in water refers to the concentration of dissolved calcium and magnesium, with higher mineral content leading to a higher hardness level. While calcium and magnesium are naturally occurring minerals that aren’t generally harmful to your health, they can contribute to a variety of issues for you and your home.
Health Canada distinguishes carbonate, or temporary hardness, from non-carbonate, or permanent hardness. Temporary hardness can form scale when water is heated, while permanent hardness is associated with calcium and magnesium sulfates or chlorides.
What causes hard water?
As water moves through soil and rock, it can pick up dissolved calcium and magnesium before reaching your tap. The U.S. Geological Survey notes that groundwater picks up hardness minerals this way. Limestone and other calcium- or magnesium-rich formations also can contribute to hard water.
Municipal and private well water can both be hard, with levels varying by local geology and water source. Municipal water can still be hard because treatment there is typically aimed at meeting federal drinking water safety regulations and does not always address aesthetic issues like hard water.
How is water hardness measured?
Water hardness is commonly measured in grains per gallon (gpg), milligrams per liter (mg/L) or parts per million (ppm). One grain per gallon equals about 17.1 mg/L.
Hardness classifications can vary. The Water Quality Association uses the following water hardness scale:
| Water hardness level | Grains per gallon (gpg) | Milligrams per liter (mg/L) |
|---|---|---|
| Soft | Less than 1 | Less than 17.1 |
| Slightly hard | 1-3.5 | 17.1-60 |
| Moderately hard | 3.5-7 | 61-120 |
| Hard | 7-10.5 | 121-180 |
| Very hard | More than 10.5 | More than 180 |
Higher hardness levels can make mineral deposits and hard water scale more noticeable. A water test is the best way to measure your water hardness level.
Schedule your free water test.
What are the signs of hard water?
Hard water is often most noticeable through its effects around the home. Over time, hardness in your water can also impact water-using appliances, including your washing machine, dishwasher and hot water heater, as well as fixtures and drains. Signs of hard water include:
- Residue on skin and hair: When hard water combines with soap, it can create a residue that’s difficult to rinse from hair and skin. Your skin may also feel dry or irritated after a shower.
- Soap scum: Hardness minerals also react with soap to form soap scum that can collect on shower doors, tubs and fixtures.
- soap also can contribute to soap scum on your dishes, shower doors and fixtures.
- Buildup in pipes and on fixtures: Mineral deposits can accumulate inside pipes and showerheads, restricting water flow and water pressure over time.
- Ineffective cleaning: Hard water makes soaps and detergents less effective and can leave buildup on fabrics, making clothes and towels feel stiff or scratchy.
These signs can indicate a hard water issue, but testing confirms your water hardness level.
How does a water softener address hardness?
Culligan’s water softening solutions remove calcium and magnesium, the minerals that cause hard water. Typically installed on your home’s main water line, a softener treats water before it flows to your faucets, showers and appliances.
Inside the system, tiny resin beads capture calcium and magnesium and exchange them for sodium ions—a process called ion exchange. Periodically, the system regenerates using a brine solution to flush the captured minerals from the resin and replenish its sodium ions. The used brine is sent to the drain, and the resin is ready to soften water again.
Water filtration addresses other concerns, such as sediment, chlorine taste and odor, or specific contaminants. When hardness is the primary issue, a water softener is the appropriate solution.
Water hardness FAQs
These answers address common questions about hard water, soft water, water softening and testing.
What is the difference between hard water and soft water?
Hard water contains higher levels of dissolved calcium and magnesium, the minerals that cause hardness. Soft water contains little of these minerals, so it’s less likely to leave mineral buildup and allows soaps and detergents to work more effectively.
Is hard water the same as contaminated water?
No. Hardness itself is not a health concern, but it does not tell you whether other water quality issues are present. If you have concerns beyond hardness, a local Culligan water expert can help determine what additional testing may be appropriate.
Can a water filter reduce water hardness?
No, standard water filtration systems are not designed to remove the dissolved calcium and magnesium that cause hardness. To address hard water throughout your home, a water softener is the appropriate solution.
How can I find out my water hardness level?
A water hardness test measures the amount of dissolved calcium and magnesium in your water. The results show how hard your water is and can help you determine whether your home would benefit from a softener.
If hard water is affecting your home, schedule your free, in-home water test and consultation. A local Culligan water expert can test your water and discuss your household’s water use and concerns to recommend a solution that fits your needs.
