Self-regenerating Water Softeners Can Degrade Groundwater Quality
|The salt used in automatic self-regenerating water softeners is discharged into the public sewer system. This increases the salinity of recycled water used to irrigate the community's landscaping, and ultimately degrades groundwater quality.
We strongly discourage residential customers from installing automatic self-regenerating water softeners—the kind that use rock salt or potassium chloride pellets. They discharge very salty brine into the public sewer system, which in turn increases the salinity of recycled water used to irrigate community landscaping. The salt in recycled water seeps back into our groundwater basin where it degrades the quality of our drinking water supply.
Our wholesale water supplier, Zone 7 Water Agency, operates a demineralization plant to remove salt from groundwater, but this is an expensive process. The more automatic water softeners that are used in the district, the higher the costs for all customers.
District Code, section 5.20.120, prohibits commercial customers from discharging the brine from water softener regeneration into the public sewer.
Are There Good Alternatives?
If having soft water is important to you, please consider using an exchange tank service. The company will install portable softening tanks at your home and replace them on a regular schedule. The company disposes of the brine in the tanks under controlled conditions so it never enters our wastewater, recycled water, or groundwater basin.
You may also want to consider a “no-salt” water-softening system, such as those that use activated carbon adsorption, reverse osmosis, or other technologies. DSRSD cannot endorse any product or technology, nor provide any assurances regarding the effectiveness of any water treatment system.
We suggest researching product reviews as well as manufacturer information. One place to look is the Sanitation Districts of Los Angeles County website. They have compiled a searchable directory of no-salt water softening alternatives.
How Hard Is our Water?
We measure hardness by the amount of calcium carbonate (a naturally occurring mineral) in the water, expressed either as milligrams per liter (mg/L) or grains per gallon (gpg). Our water is moderately hard to hard and 90 percent of samples are in the range of 109-336 mg/L (6-20 gpg).
Because our water is a variable blend of surface and well water, hardness changes throughout the year and by location in the district. During shortages of surface water supplies (such as from the State Water Project), water hardness can be higher than normal because Zone 7 is blending in more groundwater. Zone 7 also may minimize operation of its demineralization plant to conserve water.
How Automatic Water Softeners Work
Self-regulating (also known as “automatic”) water softeners exchange calcium and magnesium (“harder” minerals found in water) for “softer” minerals—usually sodium or potassium, called “salts.”
The ion exchange occurs as hard water passes through a resin bed. Periodically, the resin must be "regenerated" with a concentrated salty brine. The leftover brine from this operation goes down the drain, into the public sewer.
Pros and Cons of Softened Water
- Water softeners eliminate mineral deposits that cause hard water spots on dishes, glasses, and silverware.
- Appliances tend to last longer.
- Many people prefer the taste of soft water.
- Softer water reduces scale in pipes, kettles, tanks, baths, and showers.
- Soaps and detergents produce more suds in soft water, reducing the amount of soap needed.
- Physicians may discourage persons on a low-sodium diet sodium from drinking water softened with sodium. However, low-sodium diets usually allow water softened with potassium.
- Excessive concentrations of salts can be harmful to the environment and can prevent wastewater from being economically recycled. DSRSD discourages the use of self-generating water softeners because they add salt to sewage.
- Water softeners can be expensive to install and maintain.