What I love about the water treatment industry is that no project is ever exactly the same. Whether it’s the influent water quality, the desired output water quality, or how that water will be used, each water quality improvement/management project depends on environmental, physical and personal variables.
To some people, “acceptable” water is water that’s safe enough to drink, for others, it has to be purified to >18 Mohm•cm resistance and contain no Total Organic Carbon and Pyrogens. When it comes to mission-critical applications, we have the convenience of ASTM D1193, USP and Ph.Eur. water specifications for specific grades of water to ensure that there is no confusion in what we provide. In less-critical applications, the definition is often left open to interpretation by the client, vendor, and equipment supplier with the possibility to fail catastrophically in meeting the client’s expectations.
Something as simple as “soft water” or “water softener” are terms that I’ve seen adults get into shouting matches and professional feuds over what each really means.
At the most elementary level, most people understand that “hard water” is water where it is hard to get soap to lather, so it follows intuitively then that water where soap lathers easily should be called “soft” water.
We understand from the chemistry of calcium and magnesium reactions with soap, that “hard” water contains high amounts of minerals that interact with the soap. These calcium and magnesium minerals are responsible for the inhibitory effect on soaps suds as well as the formation of hard water scale on pipes, faucets, fixtures, glassware, and heating surfaces.
For almost a century, people have typically purchased water softeners to address one or both of the following issues:
Soap Interactions
Soap interacts with hard water minerals, causing significant negative effects to the user. It takes more soap and other cleaning products to get things clean, glasses are cloudy, silverware is spotted, whites are gray and dingy, hair and skin are affected, and life in general is “harder”.
Mineral Scale and Precipitation
Hard water scale is easily recognized as the cloudiness on glasses, spots on silverware and crustiness on faucets, showerheads and other fixtures. Hidden scale and precipitation is harder for users to notice until electric water heater elements scale over, tanklesss water heaters lose flow, or the gas-fired water heater starts to make “snap, crackle, and pop” noises.
Physically removing calcium carbonate hardness ions to a level of approximately 2 gpg (34.2mg/L) is recognized by industry experts as “water softening”. Removing hardness ions from the water ensures that the soap and scale interactions cannot occur.
A traditional salt-based (sodium or potassium) ion-exchange water softener is currently the most cost-effective way to address both scale and soap issues on the market. There are some legitimate concerns about salt-based ion-exchange systems:
Salt consumption (cost and inconvenience) – Ion exchange systems use either sodium or potassium salt to regenerate. The easiest way to provide sodium or potassium to the softener is with cheap, ubiquitous chloride salt. The net environmental impact from harvest, packaging, storage, and transportation of salt is typically outweighed by the resource, labor, and material savings that these types of softeners provide. The resource-efficiency of salt-based systems continues to improve thanks to resin matrix enhancements, upflow regeneration, improved brining and reserve algorithms, along with the use of resin exhaustion sensor technologies.
Brine Discharge – When a salt-based softener regenerates itself, a concentrated solution of calcium chloride and other ions is flushed to drain along with associated backwash and rinse water. Concerns have been raised at the municipal and small systems level about chloride concentrations in wastewater. Softener bans in California have yet to show significantly beneficial results that justify the loss of convenience and energy/resource savings to the homeowner/business when removing salt-based softeners.
Some homeowners don’t like the feel of water produced by sodium-based water softeners (no it’s not the body’s natural oils – stop perpetuating that silly myth, you’re embarrassing yourself). While relatively easily remedied with different regeneration strategies, and various resins, some people will eschew purchasing a water softener because of this personal preference.
Other homeowners simply don’t want to deal with the hassle of hauling salt. There is an obvious need in the marketplace for salt-free alternatives to address scale and soap issues.
The Quest for alternatives
Salt-based Ion exchange is not the only way to physically remove hardness ions. Membrane separation with Nanofiltration or Reverse Osmosis membranes is a proven method of “softening” the water. Another method of hardness removal is electrodeionization (EDI), where hardness ions are selectively removed using arrangements of ion exchange membranes that regenerate electrochemically instead of using salt. These are true salt-free softening technologies where the efficacy can be very easily tested by measuring the amount of calcium carbonate in the product water. Like salt-based softening technology, these alternative technologies have their own strengths and weaknesses to be considered before use.
There are times when space, electrical supply, drainage availability or maintenance concerns prevent someone from being able to purchase a traditional water softener, or other softening technology like EDI, or membrane separation. Instead of these people being left with no alternative, the free market has provided a plethora of products to compete for the customer’s business.
I have yet to see a technology that truly softens water outside the realm of ion exchange or membrane separations. I am excited for the day when such a technology is developed; it will be one the most significant technological breakthroughs of the century.
There are many salt-free devices for sale, using various approaches like magnetism, radio frequency, ultrasonics, pressure modulation, heat modulation, organic acids, mono/bi/trimetallic reactions, phosphate compounds, chelating agents, and various iterations of media-assisted crystallization. Some do not work at all, but I have seen salt-free scale control options in the marketplace that actually work well under certain chemical and operational conditions in reducing and even preventing hard water scale accumulation. My frustration with most salt-free vendors is the lack of consistent, repeatable, verifiable data on where, when and why these technologies will perform or not perform.
To make matters worse, due to loose definitions and overzealous marketers, some products are promoted as more than what they really are. When playing fast and loose with definitions like “softener”, you will inevitably disappoint a customer who might even feel that they were deliberately deceived. If a device doesn’t physically remove or sequester water hardness, then it is simply not a softener and should not be claimed as such.
Responsible companies are calling these appliances “scale-control” devices, or “water conditioners” to help minimize confusion in the marketplace. This is a healthy first-step in ensuring consumer confidence and satisfaction, but we still need more disclosure to help us know when something will work. “Just buy it and see how it works”, is not an acceptable answer to the dealer or their client.
The next step in being a good corporate citizen is to be honest, scientific, and objective about when, why and how your device will work. Much like the difference between nails and screws, each has their place of strength or weakness, and no one product is going to work perfectly for every application. Some salt-free devices work rather well in particular hardness ranges in some areas, but not in others, much to the frustration of plumbers and end-users who are excited to adopt more efficient and economical technologies. Very few manufacturers have disclosed when and why their devices work or what the exact interference factors are.
This has been and continues to be a problem in the “alternative treatment technologies” realm, especially when it comes to delivering environmentally friendly, cost effective solutions to our customers. I think this is shortsighted and limits their credibility in the marketplace.
I am very excited about a proposed Water Quality Research Foundation (WQRF) project to assess the capabilities of salt-free technologies by conducting credible 3rd-party benchmarking tests. Potential outcomes of research surrounding this topic could include the validation, creation or amendment of industry standards as well as corresponding professional and consumer education. This study could measure salt-free technologies against the IAPMO Z601 standard and measure the scale reduction effects inside residential water heaters (tank and tanklesss). It could also measure the scale build-up and ease of removal from glass shower doors and coffee makers. IAPMO is currently considering a new standard for scale reduction devices that proposes a very low threshold for efficacy (60% scale reduction). This type of research could address the consumer impacts of poor performance and help prevent the adoption of this low efficacy threshold in plumbing codes.
I am objectively open to explore all “alternative technologies” and not at all biased towards a “salt-based ion exchange only” mindset. Just as with ion-exchange or membrane separation technologies, I need to understand how something works, when it will and won’t work, and how to measure efficacy of the technology before I stake my reputation or client’s money on it.