Comparing the efficiency of water softeners
A wide variety of products are labeled as high efficiency, including light bulbs, washing machines, HVAC systems and water softening systems. Knowing the efficiency standard used for residential water softeners helps determine what high efficiency means and how products compare to one another. It seems every company claims to have high-efficiency water softeners these days. What makes one company’s high-efficiency water softener different from another’s? How can one compare different water softeners and understand what companies mean when they claim a product is efficient?
Defining High Efficiency
For a residential water softening system to be considered efficient, it must conform to NSF/ANSI Standard 44. This standard is only used for demand-initiated regeneration water softeners and not for time clock-controlled systems. Softeners rated by this standard have a salt efficiency of at least 3,350 grains of total hardness exchange per lb of salt and shall not deliver more salt or be operated at a sustained maximum flow rate greater than their listed rating. They also have a rated water efficiency of at least 1,000 grains of capacity per 5 gal of regenerated water. The rated salt and water efficiency is measured by an independent, third-party laboratory that adheres to the test parameters described in the standard. Currently, only California has a higher standard, requiring salt efficiency of no less than 4,000 grains per lb of salt.
Laboratory efficiency tests can vary from real world applications or operational efficiencies of water softeners. Various factors affect operational efficiencies, including initial setup or programing by the installer, type of plumbing, water pressure, water usage, total compensated hardness, and turbidity.
Counter-current regeneration allows for lower brine rates, more concentrated brine and increased cation exchange resin contact time.
Compare OEM-Supplied Data
The best way to compare water softeners is with a performance data sheet. Most OEMs publish performance data sheets for their water softening products. The data sheets provide technical performance specifications, including maximum service flow rates and salt and water efficiencies. However, they do not disclose the factors that make one system more efficient than another, such as system design, valve operation, and type and quality of materials used, including high-quality resins, which can improve the consistency of more efficient regenerations.
System design and valve operation are the primary contributing factors to efficiencies. With recent advancements in water softening controllers, the industry has adopted counter-current versus co-current regeneration. Counter-current regeneration is the flow of water opposite the direction of the service flow, referred to as up-flow. Regenerating in the up-flow allows for more concentrated brine, lower brine flow rates and increased contact time with the cation exchange resin.
In the Eye of the Consumer
Consumers typically look for products labeled efficient to save money, perform less maintenance and reduce their carbon footprint. The phrase “high efficiency” also has become synonymous with the best products available.
Water usage for most softener regeneration and the water wasted during regeneration are points of concern for consumers, especially during droughts and water shortages. Consumers also want to minimize maintenance requirements, like lugging bags of salt. While the cost of salt can be insignificant in comparison to an old time clock water softener, the cost of a broken back is not. Salt affects consumers’ buying decisions. Some of the truly high-efficiency water softeners help address these issues by using up to 40% less water and salt than others.
Perception of efficiency or product quality using the words high efficiency is also notable. If given the choice between a water softener and a high-efficiency water softener, which water softener would the consumer choose?
Under NSF/ANSI Standard 44, water softeners are certified as efficient if they can exchange 3,350 grains per lb of salt. When conducting a comparison of water softeners with performance data sheets, water softening systems have a range of grains exchanged per lb of salt. By these parameters, any water softener that exchanges higher than the standard would be considered highly efficient.
Finding a truly high-efficiency system will take research on the part of the consumer, and whether a system is deemed high efficiency based on exchanged grains per lb is ultimately the buyer’s decision.