If you live in an area with hard water, you know how frustrating it can be to deal with limescale build-up, soap that doesn’t lather and laundry that doesn’t quite feel clean. A salt-based water softener is the most effective way to fight the effects of hard water, but is this method actually hurting the environment?
How Water Softeners Work
Water softeners use ion exchange or replacement to “remove” hard water minerals from the water. With a salt-based system, magnesium and calcium ions are replaced with sodium ions.
The sodium ions leave the resins in the tank and move into the water, while the magnesium and calcium ions attach to the resins. Essentially, the sodium ions and the calcium and magnesium ions switch places.
The exchange process takes place in a resin tank or chamber. The hard water passes through, the ions switch places, and the soft water exits the drain. Instead of magnesium and calcium ions, the water now contains sodium ions.
When there are no sodium ions left in the resins, the system can no longer “soften” the water. At this point, the tank is “full” and the system must go through the regeneration (or back-flushing) process.
More salt is added to the exchange tank during regeneration, which displaces the magnesium and calcium ions and replaces them with sodium ions. Once regeneration is complete, the resins are ready to start softening water again.
But these resins won’t last forever. Over time (and after many regeneration cycles), their ability to perform ion exchanges diminishes significantly.
The polymeric resins used in the exchange tank last about five to ten years, after which they need to be replaced.
The Environmental Benefits of Softeners
Salt-based water softeners aren’t perfect, but they do offer some environmental perks.
Improve Energy Efficiency
A study out of France found that an increase of just 1mm in scale can reduce heating efficiency by 6%.
A separate study from New Mexico State University found that gas heaters running on hard water used more than 29% more energy.
Save Your Clothes
The Chicago YMCA laundry conducted a survey on water softening, and found that soft water increased the life of bath towels, sheets and pillow cases by up to 40%.
The minerals in hard water make it difficult for soap to lather, which can leave fabrics feeling dirty and filmy.
Use Less Soap and Detergent
Studies have shown that people use more than double the amount of soap with hard water compared to soft water.
The Environmental Impact of Salt Water Softening
Soft water certainly has its perks. Clothes come out cleaner, you lose less detergent and limescale build-up becomes a thing of the past. But softening also has its drawbacks: it can be harmful to the environment.
Uses More Water
Increases Water Treatment Costs
Estimates suggest that it costs $5 to remove a pound of chloride at water treatment plants. Water with high salinity is more expensive to treat and is difficult to reuse for industrial or irrigation purposes.
Wastewater from salt-based softeners contain high levels of magnesium, calcium, potassium, sulfate and chloride, which treatment plants are not equipped to remove.
Some coastal states are looking into constructing separate treatment facilities for soft water systems, and complex pipeline systems to redirect salt water back to the ocean. Building additional treatment plants and pipelines can be quite costly for local governments, which will, in turn, be more expensive for taxpayers.
Raises Salt Pollution Levels
Salt is considered a pollutant in many states. Yes, scaling makes detergents less effective and reduces the life of plumbing systems. But wastewater from ion exchange systems can negatively affect local marine life, ecosystems and agriculture.
Water with high salinity can cause leaf burn and harm local marine life.
Higher Lead and Metal Levels
Many people believe that softened water is unhealthy to drink, particularly for hypertensive patients.
But along with sodium, soft water may also contain higher levels of lead and metal. Soft water is more likely to leech metals from plumbing systems and pipes, particularly the lead from joints, copper from the pipes and the metal from your faucets.