Hard water contains high levels of minerals like calcium and magnesium. These minerals make the water “hard” and can cause problems like scale buildup, mineral spots, dry skin and hair. Using a water filter is an effective way to soften hard water and remove these problematic minerals.
In this article, we’ll look at:
- What is hard water?
- The problems caused by hard water
- Do water filters remove hard water minerals?
- The best water filters for hard water
- Water softeners vs. filters for hard water
- Whole house vs. point-of-use filters
- How to maintain your hard water filter
Page Contents
What is Hard Water?
Hard water contains high dissolved mineral content, mainly calcium and magnesium. These minerals enter the water as it flows through soil and rock formations like limestone or chalk that are naturally rich in calcium and magnesium.
Water hardness is measured in grains per gallon (gpg) or milligrams per liter (mg/L). The general classifications are:
| Water Hardness Level | Grains per gallon (gpg) | Milligrams per liter (mg/L) |
|---|---|---|
| Soft | 0-3 gpg | 0-50 mg/L |
| Moderately hard | 3-7 gpg | 50-120 mg/L |
| Hard | 7-10 gpg | 120-180 mg/L |
| Very hard | Over 10 gpg | Over 180 mg/L |
Hard water is found across the U.S. but is most common in areas with limestone, chalk or other calcium/magnesium-rich geology like:
- Most of the Midwest and Great Plains states
- Southern states like Texas, Oklahoma, Arkansas, Louisiana
- Western states like Arizona, Utah, Colorado
- Central and Northern Florida
Problems Caused by Hard Water
The minerals in hard water can cause a variety of nuisance problems:
Scale Buildup
As hard water evaporates, the minerals are left behind and form solid calcium and magnesium deposits known as scale. Scale can gradually buildup on the inside of pipes, hot water heaters, boilers, and other equipment. This reduces flow and efficiency.
Mineral Spots and Film
Hard water leaves a noticeable white mineral residue when it dries. You’ll see stubborn spots on dishes, glasses, fixtures, windows and more. It also leads to a dull mineral film on surfaces that have been cleaned.
Dry Skin and Hair
The minerals in hard water can be drying and irritating to skin and hair. Many people find their skin is itchy and dry after showering in hard water.
Soap Residue
Hard water reacts with soap, leaving an insoluble film on skin, hair, and clothing. No matter how much you rinse, you can’t wash the sticky residue away. Because of this, it’s difficult to clean well with hard water.
Appliance Damage
Over time, mineral scale accumulation can damage appliances and fixtures. Hard water leaves deposits inside dishwashers, washing machines, coffee makers, humidifiers, and more, potentially shortening appliance life.
Do Water Filters Remove Hard Water Minerals?
Yes, water filters are very effective at removing hard water minerals like calcium and magnesium. They work by forcing the water through a granulated mineral media, often called ion exchange resin or zeolite.
As the hard water passes through the filter media, the calcium, magnesium and other minerals are attracted and bind to the surface of the granules. The water flowing out is then “softened” and free of the hardness-causing minerals.
Ion Exchange Softening
The mineral media acts as an ion exchange resin. It has a negative charge, which exchanges the hardness minerals for more soluble sodium ions. The calcium and magnesium ions are retained in the filter while sodium ions are released, softening the output water.
Catalytic Filtration
Some filters use catalytic activated carbon with a slight electropositive charge. This attracts the negative hardness minerals. The minerals coat the surface of the carbon particles instead of exchanging ions.
Both ion exchange and catalytic filtration are reliable methods for reducing water hardness and associated problems.
The Best Water Filters for Hard Water
There are a variety of effective filter types for softening hard water:
1. Salt-Free Water Softeners
Salt-free (or saltless) water softeners use ion exchange to remove calcium and magnesium ions while adding potassium. This creates softened water without the need to periodically recharge with sodium chloride salt.
Pros:
- Soften water without salt, sodium or chemicals
- Reduce scale and mineral deposits
- Improve lathering and cleaning ability of soaps/detergents
- Prevent mineral spots on fixtures and dishes
- Reduce accumulation on appliances
Cons:
- Require filter media replacement
- May not fully prevent scale depending on water hardness
- More expensive than salt systems initially
2. Magnetic Water Softeners
Magnetic water softeners use magnets to alter the structure of the mineral compounds in hard water. This prevents them from bonding together and forming scale.
Pros:
- Do not require salt or filter media replacement
- Prevent scale formation
- Simple installation
Cons:
- Does not reduce pre-existing hardness
- May not work well for very hard water
- More research needed on effectiveness
3. Reverse Osmosis Systems
Reverse osmosis (RO) uses water pressure to force water through a semipermeable membrane, filtering out minerals. RO removes 92-99% of calcium and magnesium minerals.
Pros:
- Most thorough filtration of hard water minerals
- Also filters out other contaminants like lead, arsenic, fluoride
- Improves water taste and odor
Cons:
- More expensive than other options
- Wastes water during filtration process
- Membrane may need periodic replacement
4. Water Softening Pitcher Filters
Pitcher filters with a built-in water softener are convenient and affordable. They use ion exchange resin to bind hardness minerals and reduce their effects.
Pros:
- Inexpensive
- Easy to use
- Provide softened water on demand
- Reduce spots, film, soap scum
Cons:
- Limited filter capacity
- May need frequent cartridge changes
- Only filter small amounts of water at a time
Water Softeners vs. Filters for Hard Water
While water softeners and filters both address hard water issues, there are some key differences:
Water Softeners
- Method: Ion exchange softening
- Hardness Removal: Exchange hardness minerals for sodium ions, fully softening the water
- Sodium: Increase sodium content in water, may be a health concern for some
- Efficiency: Very effective for all levels of hardness
- Cost: Moderate, but requires regular salt purchases
Water Filters
- Method: Ion exchange, catalyst filtration, reverse osmosis
- Hardness Removal: Partially reduce hardness minerals
- Sodium: Do not add sodium
- Efficiency: Varies based on technology. Moderate to high effectiveness.
- Cost: Varies. Overall less expensive than water softeners.
Water softeners are typically better for very hard water and when complete water softening is needed. Filters reduce hardness to a lesser degree but are simpler, more economical solutions.
Whole House vs. Point-of-Use Filters
Water filters come in whole house and point-of-use options:
Whole House
- Install on main incoming water line
- Soften all water entering home
- Higher capacity and flow rate
- More installation work
- Higher upfront cost
Point-of-Use
- Install on faucet, showerhead, under sink
- Soften water at specific locations
- Smaller capacity and flow
- Simple DIY installation
- Lower cost
Whole house systems fully soften all your water but are a bigger investment. Point-of-use filters are more affordable and can target problem areas like laundry or kitchen sinks.
How to Maintain Your Hard Water Filter
To keep your water filter working properly:
Replace Filter Cartridges
Most filters use a disposable cartridge that needs replacement every 6-12 months. Follow manufacturer guidelines for exchanging cartridges.
Use a Sediment Pre-Filter
Sediment pre-filters protect your water softener from dirt, silt and particles that cause clogging.
Clean the Resin Bed/Membrane
Over time, resin beds and RO membranes can foul with mineral deposits. Perform occasional deep cleaning and regeneration.
Check Water Usage
Monitor water usage to ensure the filter is sized properly and change media/membrane before it’s fully exhausted.
Test Hardness Levels
Use test strips to periodically check incoming and filtered water hardness levels.
Inspect for Leaks
Check for leaks around fittings and connections. Fix any issues immediately to prevent scale buildup or wasted water.
Conclusion
Water filters are highly effective for removing calcium, magnesium and other minerals that make water hard. While not a complete solution in all cases, filters can significantly soften hard water and help minimize scale buildup, mineral spots and residue, dry skin and hair, and other problems.
Choosing the right type of water filter and proper maintenance are key to getting the best performance from your hard water filtration system.