Water softeners and salt efficiency

A retrospective and update of current technologies.

Throughout the past 30 years, manufacturers of residential automatic water softeners have been challenged with the task of making their equipment as efficient and environmentally friendly as possible.

While water softeners today are considered a common household appliance, manufacturers continue to advance the technology.

History of salt efficiency

In response to environmental concerns, many municipal utilities enacted laws in the late 1970s to control the level of Total Dissolved Solids (TDS) that automatic water softeners could emit with effluent water.

To address these new laws, the water softener industry came together to form the Ion Exchange Task Force of the Water Quality Association.

Comprised of technical volunteers from dealers, manufacturers, and certification and testing labs, the IETF is charged with the task of updating certification processes while reviewing and developing educational materials.

With the initial collaboration of the task force, the term salt efficiency emerged.

Referring to the hardness removal capacity of a water softener unit, the term is measured by grains of hardness removed divided by the weight of salt in pounds used to achieve a particular amount of hardness reduction.

The industry established 2,850 as a target salt efficiency in the early 1980s.

In addition, the term operational salt efficiency?was born. That is, the salt efficiency performance of a water softener under conditions of actual operation or simulated long-term use (6 months or more) in a household where gallons of water usage typically varies day to day.

New terms, new goals

Armed with a new goal, the industry established 2,850 as a target salt efficiency in the early 1980s. At this level, dramatic design changes were not necessary.

Instead, the addition of basic tables were incorporated into field training and manuals to ensure that softener installers knew how to set salt settings and timers.

However, to ensure that their equipment would operate more efficiently when iron, manganese and copper were present, select manufacturers began installing demand regeneration devices on their softeners.

Comprised of water meters and water quality sensors, these devices allowed the softeners to regenerate based on need, therefore efficiently addressing the issue of variable water usage.

The bar raised again

In the late 1980s, a new efficiency standard of 3,350 was established. This standard is still used today in the ANSI NSF Standard 44.

When this new rate was established, manufacturers made design changes to their systems, including new inductor designs, tank configurations, manifolds, and distributors, to name a few. No work was done to the brine system or the actual salt itself.

In the late 1990s, however, the state of California raised the bar by requiring all water softener systems to meet a salt efficiency standard of 4,000.

In addition, the state has required that all softeners installed after January 1, 2002 operate on a meter or hardness sensor.

While many manufacturers were ahead of this curve, the requirement has caused the industry at-large to develop much more efficient designs.

California has required that all softeners installed after January 1, 2002 operate on a meter or hardness sensor.

Up and coming technology

Salt discharge and salt efficiency continue to be a concern for many communities across the country.

As a result of local regulation and increasing market demand, manufacturers are focusing research and development resources on the development of systems that use salt with greater efficiency, or produce softened water using no salt at all.

Among the new technologies that do not use a traditional brine solution are the following:

Membrane technologies:

Comprised of systems such as reverse osmosis (RO) and nanofiltration (NF), membrane technology is optimal for water concerns that include and stretch beyond traditional hardness.

By selectively separating components over a wide range of particle sizes and molecular weights, these systems not only reduce calcium and magnesium from the raw water, but a wide variety of additional minerals and contaminants that may be present.

Widely available, membrane technology is significantly more expensive than the ion exchange technology used in today automatic water softeners.

Physical treatment:

Including the use of electricity, magnets, or combinations of pulsed energy, physical treatment refers to energy modifications that are applied to the crystal structure of hardness elements, such as calcium and magnesium.

While this technology is relatively inexpensive and especially environmentally friendly, its effectiveness has been debated.

Physical treatment refers to energy modifications that are applied to the crystal structure of hardness elements.

Electrochemical technology:

Because calcium and magnesium carry a charge, electrochemical technology uses ion-selective membranes or resin as a transport mechanism to attract these elements out of the water.

Electrochemical technology is relatively expensive and may not deliver the level of softness delivered from traditional brine solution.

Final decision

The industry has come a long way from the early water softener designs. And while new technologies offer environmentally friendly, often cost-effective ways of reducing hardness, consumers, with the guidance of water treatment dealers, will have to determine the level of softness they expect from their water.

For those whose main concern is having the softest water possible, or a level of less than 1 grain hardness, traditional brine solution technology continues to be the most effective.

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