Many people are worried about salt in their diet, so the idea of salt in their water from a softener is seen as a further opportunity to reduce salt. What most people don’t realize is that the amount of sodium in your treated water is directly proportional to the amount of hardness that your raw water has.
First, lets talk about the role of salt (or brine) in a water treatment system. The way a softener works is that as water passes thru the media in the tank, the media (using ion exchange) will attract the Ca+ (calcium) and Mg+ (magnesium) ions that are dissolved in the water and make up what is called “hardness”.
The media currently holds Na+ (sodium) ions and when the Ca+ and the Ma+ ions are attracted, they bump the Na+ ions off into the water that comes out of the softener. Eventually, the media runs out of “capacity” and is unable to attract any more Ca+ or Mg+ ions. At this point, the softener goes into “regeneration” with is several processes, one of which is called “backwash” which floods the media with brine water from the brine tank beside the unit.
This brine water is as highly concentrated as possible and will bump the Ca+ and Mg+ ions off of the media, replacing them with Na+ ions. This highly concentrated brine water with the Ca+ and Mg+ that has been cleaned off of the media is then discharged from the tank into either the sewer, the septic, or wherever the health department has determined it needs to go.
Salt (or brine) does NOT directly touch or enter your drinking water unless there is a malfunction of the equipment! Some Na+ is left behind on the resin as a place holder to be bumped off when the softener goes back into normal operations. The easiest way to remember this is that salt is basically only used as a detergent to clean the media of the softener.
This “regeneration” cycle should happen at a minimum of every 12 days or the media will begin to channelize and will lose the capacity to “soften” water. Because this process can be time consuming and has some noise associated with it, this cycle is normally scheduled for 2 am when the fewest people are still active and needing the use of the water.
When the regeneration happens, the softener is in bypass mode and, if the water is used, untreated water will enter the water lines. If the household needs treated water at all times, 24×7, then twin tanks can be used so that at least one tank is always in service.
To understand how all this relates to how much sodium is in your water, I will give you a little better idea of what level of hardness is considered “bad”. Consider the following guidelines: 0 – 3 grains = soft, 3 – 6 grains = moderately hard, 6 – 9 grains = hard water, 9+ grains = extremely hard.
In SW VA, it is not unusual to see a variety of hardnesses – anything from very soft (around 2 grains) to extremely, extremely hard (in excess of 40 grains). We have even tested hardness up to 91 grains in one instance.
As I indicated above, a softener will remove Ca+ and Mg+ ions from the water and exchange them for Na+ ions, thereby putting “salt” in the water. Since two Na+ ions are exchanged for every Ca+ or Mg+ ion removed, once you know the hardness of the water, you know how much sodium is left in the water by a softener.
Using a “normal” level of hardness for the area of 20 gpg (grains per gallon), a softener will put 596 mg of Na+ into one gallon of water or 149 mg of Na+ into one quart of water.
To put that into perspective, one ounce of potato chips has about 150 mg of sodium – which is approximately 17 potato chips. You would have to drink an entire quart of water to get that 149 mg of sodium.
However, that being said, if you are on a salt-restricted diet, please consult your physician with the actual numbers to see if you should have additional equipment to remove the 149 mg of sodium. The best way to remove the added sodium is with a reverse osmosis system.
Most affordable residential RO systems only treat the water at a single kitchen faucet and usually only at a separate faucet from your “usual” water. However, there are whole-house systems available and you are really only limited in how much you are willing to pay for them.
The next question is “Why should I remove the hardness at all?” Well, go to our page on Energy Efficiency with Water and get your answer there!
One of the better descriptions of hardness is on AquaScams. The webpage also has a good discussion of water scams and is well worth someone spending some time reading the information.
There are a lot of people out there who are trying to sell you on the next best thing – the next greatest gimmick. As you well know, you have to be extremely careful about “jumping on the bandwagon”.
We have been asked about “salt-free water softeners” many times over the last several years. Our feeling is that if there was such a system that worked well and was supported by published scientific data, we would seriously consider offering such a system to the public.
At this point in time, we have not found a “salt-free water softener” that we are willing to service and maintain.