Soft Water not for Drinking? – Is softened water corrosive?

An end-user forwarded a link to me last week and she had lots of concerns…

She saw it on a website for a company touting a “salt-free” softener/scale control system. Naturally the salt-free company was using the material to “bash” softened water and ion exchange softening systems in general…This is a common tactic employed by uneducated and sometimes even unethical people. She is in the process of purchasing a Crusader Twin Analyst Softener from her plumber and she wants to make sure that her buying decision is a wise one; the concerns raised by the article caused her to rethink even wanting to soften her water at all.

Hard water contains calcium and/or magnesium ions. These ions make soap hard to lather, giving hard water its name. For water to be called “soft”, it must be devoid of these hardness ions. There is a significant difference between “naturally soft” water and “ion exchange softened” water.

Naturally soft water is water that generally tends to be aggressive, since it has no significant buffering mineral content to begin with. Naturally soft water usually contains carbonic acid (derived from carbon dioxide), tending to lower the pH of the water, which contributes to corrosive conditions and can cause significant problems in homes, business, and industry. Since naturally soft water is so potentially detrimental, many people will recommend adding calcium/magnesium hardness to water to protect from corrosion.  When water is acidic, it makes logical sense to add hardness to balance the pH and raise the total alkalinity to protect from corrosion. This is the essence of the Langlier Saturation Index (LSI), which essentially draws a correlation between calcium hardness, and water’s tendency to be “corrosive” or scaling”.

Some well-intentioned, but uneducated people feel that keeping water “hard” is the safest for building operations and possibly even for human consumption. This is a counter-intuitive approach, since hardness can cause issues like scaling and soap interference; and water hardness is comprised of inorganic minerals, not the organic minerals that the human body requires for proper nutrition. Scaling can be addressed in a number of ways, including novel technologies like Next ScaleStop without actually removing it from the water. The calcium/magnesium hardness will still interfere with soap though and still be present to cause issues when evaporated.

Hard water scale used to only be considered an aesthetic issue, but in today’s climate of energy efficiency and environmental sensitivity, one would be foolish to overlook all the benefits of softened water.

Softened water can:

• Reduce the energy costs to heat water
• Reduce the amount of soap/detergent required to clean clothing
• Reduce or eliminate the use of dishwasher rinse-aids
• Reduce or eliminate the use of harsh chemical cleansers
• Minimize bacterial growth in washing machines
• Prolong the working life of faucets and fixtures
• Prolong the working life of appliances like dishwashers, steam irons, humidifiers, washing machines and ice makers
• Prolong the working life of water heaters and boilers
• Lower the overall carbon footprint of a home or business

There are a number of ways for hardness to be removed/isolated from interfering with soap:

• Evaporation/distillation (potentially corrosive)
• Sequestration (generally not corrosive)
• Membrane Separation (potentially corrosive)
• CDI/EDI (potentially corrosive)
• Ion exchange softening (generally not corrosive)

A water quality improvement process can only be called “softening” if it physically removes of completely sequestrates the hardness ions to a level at or below 1 grain per gallon (17.1ppm).  All methods of softening (except sequestration and ion exchange) will remove both the hardness ions as well as the buffering carbonates attached to them, and that is where the potential for corrosion can begin. Without buffering alkalinity, softened water can become corrosive, especially if it contains dissolved carbon dioxide.

The most cost-effective method currently is simple ion exchange, where calcium and/or magnesium ions are exchange with sodium or potassium ions to form relatively benign byproducts like sodium carbonate and sodium bicarbonate which contribute to the taste and feel of ion-exchange softened water. Langlier’s hypothesis is accurate until one brings ion exchange softening  into the equation. Ion exchange softening doesn’t remove the carbonates and bicarbonates from the water, thereby not making the water more acidic or corrosive. Once this principle is understood, you can see the significant difference between “naturally soft” and “ion-exchange softened” water.

Ion exchange softened water is not generally corrosive. Why do I say “generally”? – In certain conditions, if the conductivity of the water is already high, such as water with 30 gpg (grains per gallon) of hardness or higher, the softening process will contribute enough sodium/potassium to the water that is becomes very conductive which can indeed accelerate galvanic corrosion reactions.

So what does this mean? – Softened water is safe, softened water is generally good for the environment, softened water is good for your home, softened water is good for your business, and softened water is very good for your pocketbook.

An article was published back in 2006 by the Nashville Water district. It is obvious the the city of Nashville didn’t have all the facts and the article was probably posted by an over-zealous employee who was missing some information. The WQA acted swiftly to address the issue and published the following:

http://wqa.org/sitelogic.cfm?ID=850#2000anchor

“Each year, WQA communicates with cities, regulators, newspapers, and other media to correct misinformation about our industry’s products and services. In January 2006, the focus turned to Nashville, Tennessee. Their Metro Water Services department posted false and misleading information about consumption of softened water on its Web site. WQA contacted the agency in writing, refuted the article’s claims, and requested the misinformation be removed from the Web site. After receiving no response, an article was published in the January 2006 issue of WQA Industry Update. That WQA article was later picked up by another publication, which further directed the spotlight on Nashville’s Metro Water Services. As a result, the public information officer for the water agency pulled the article. She has since asked her staff to work with WQA to clear up any misleading or inaccurate information about softened water. WQA members: If you are dealing with a municipality that is making false or misleading statements about water softeners or other technologies, contact WQA immediately, and we will work to correct the information. ”

This is just another good reason to join the WQA if you haven’t already done so.

Here’s the original article for your entertainment:

“Soft water is neither healthy nor desirable for drinking! If you were a steam iron or a washing machine it would be great, but we are neither! There are good reasons you should not be drinking soft water!

Water is a universal solvent. Most materials, especially metals, are partially soluble in water. If that water is heated or softened it becomes much more aggressive at leaching metals from water lines. Lead in soldered joints and copper in pipe are particularly vulnerable and these are two of the heavy metals which shouldn’t be present in significant amounts in your drinking water.

WATER HARDNESS
Calcium and magnesium are two minerals which make water “hard.” Both of these minerals are classed as “contaminants,” but that’s a poor choice in terminology, for calcium is essential in our diet! A softener merely exchanges one group of non-toxic elements for another group of non-toxic elements. Water hardness is measured either in grains per gallon (GPG) or as calcium hardness in milligrams per liter (mg/l) or parts per million (ppm). GPG is based on calcium hardness. To convert from calcium hardness ppm, just divide by a factor of 17.2 and this gives you hardness in GPG. A soft or slightly hard water has up to 3.5 GPG; moderately hard water runs from 3.5 to 10.5 GPG; and very hard water is greater than 10.5 GPG. If your water is over 7 GPG, you might want to consider a softener just for the laundry.

Metro water is on the low side of moderately hard at 4.1 GPG (that is 70 mg/l of calcium hardness. This is an excellent value and highly desirable! Cities which have soft water are having difficulty meeting the new lead standards in tap water. Metro has had none of these difficulties in meeting the new standards!

SOFT WATER
A soft water is aggressive at leaching metals (like lead) from your lines and faucets. Most faucets are solid brass (with a relatively high lead content) and are chrome plated. This means that if you have soft water, there is a great chance that your initial drawing of cold water will have a higher lead content than normal. Hot or warm water from the tap should never be used for cooking, shortcuts, drinking water, beverages, or infant formula as it could be higher in heavy metals like lead!

WATER SOFTENERS
Besides making the water more corrosive and aggressive at leaching metals from your lines and fixtures, the zeolite beads from water softening systems may back-siphon into your toilet tanks, and the soft water may attack vital plumbing parts. While supposedly solving one set of problems, the softener could possibly introduce other problems which you may or may not be aware of! A water softener, besides leaching lead and other metals from your plumbing, can increase your sodium intake. In a water softening device hard water flows through synthetic resin beads. Sodium ions (salt) are loosely attached to each bead and the water exchanges hardness ions (calcium and magnesium) for the soft sodium ions. These devices can also be costly to run since they can waste up to 120 gallons for every 1,000 delivered.

A water softener is not designed (nor is it effective) to remove lead and other metals, chlorine, taste/odor compounds, nor chlorine by-products. Its purpose is only to make a hard water soft. Water treated to remove chlorine may encourage the formation of black rings in toilet bowls!

IN CONCLUSION…
Soft water is great for laundry, bathing, steam irons, and auto batteries, but definitely not for anything else. If you are contemplating installing a softener, there are serious questions you should ask: who will test the effectiveness of the softener, how often will these tests be run, and how will my drinking water quality be affected?

Metro Water Services does not test any home water treatment device, including softeners, and does not recommend the use of particular devices!”

Crazy article, huh? – It’s no small wonder that Nashville city quickly removed the article after it was brought to their attention by water industry professionals. Unfortunately, it’s contents have been repeated by a few other sites and the mistruths live on…