Steps for Regeneration for a Residential Water Softener
In my last column, I began to write about water conditioning and focused on the most typical condition — at least in my area — that needs to be dealt with. That condition is hardness, mainly caused by calcium dissolved into the groundwater. A water softener will remove this calcium and other hardness minerals. As I wrote in that column, this month’s topic is reconditioning softener mineral, or regeneration as it is commonly referred as.
A typical residential water softener consists of two tanks, or a tank and a tub. The first tank contains the mineral, and nowadays, is almost always made of Fiberglas, as it is under system pressure. The second tank or tub contains saltwater and either dry salt in a block form or, more often, in pellet form. You can see bags of this water softener salt in grocery stores, hardware stores, big box stores and even lumber yards. As I wrote last time, water softener mineral has the almost magic ability to exchange hard ions, especially calcium, for soft ions — the most common being sodium. Sodium, of course, is part of sodium chloride or salt.
Some people regenerate with potassium chloride. This is effective, and the resulting water has no sodium content. For people on a sodium restricted diet, this is a good thing. I have never used potassium chloride in any unit I have sold or in my own water softener. I do know that potassium chloride is more expensive than sodium chloride, and its use may be just a talking point. But, if someone who owns a water softener uses it, that’s fine. Good luck to them.
Any water softener mineral has a specific capacity. I believe that capacity is 30,000 grains per cubic foot. A typical residential water softener has 1 cubic foot in it. Larger units for larger homes or perhaps commercial use will contain 1.5 to 2 or more cubic feet of mineral. A typical 1-cubic-foot will exchange 30,000 grains before it is depleted. If we have water with 25 grains per gallon hardness, which is typical in southeast Michigan, we can soften roughly 1,200 gallons. Now, I really doubt that gallon number 1,199 will be softened and gallon number 1,200 will go through the mineral bed and remain hard. But the effectiveness does degrade. We would probably want to regenerate this softener after 1,000 or 1,100 gallons have gone through it. In my experience, a family of four would use about 125 gallons per day per person, or 500 gallons per day. This would be for bathing, flushing toilets, cooking and drinking. You could flush a toilet with hard water, but to hook up a separate system in the plumbing for that is almost never done. In addition, this hard water would leave the bowl looking pretty bad and the inside of the tank even worse. Of course, the outside sillcocks are never, ever plumbed to soft water — well, almost never.
So our 1-cubic-foot softener with our typical four-person family and 25-grain hard water is going to have to be regenerated every other day. If we had 12-grain water, we could go to a four-day regeneration rotation. If we had 50-grain water, which is unusually hard, we would have to regenerate every day or use a softener with more capacity. Per person, 125 gallons a day may seem like a lot but, in my experience, people are pretty generous with water use. I have several grandchildren, two of whom are teenagers and one who is in his late 20s, and they all like a long, long hot shower. At least they are not dirty.
To regenerate our typical softener, it will have to go through three separate stages. (This is accomplished using a control valve, and we’ll cover the design of the control valve in later columns.) Water flow through the mineral tank of our softener is typically from top to bottom. That is, it goes down through the mineral bed and then up through a center pipe and out to the distribution system. In the first stage of the regeneration process, this flow will typically be reversed. Water will go down the center pipe, up through the mineral bed and out to waste. This flushes out sediment that the bed may have trapped and perhaps a few iron particles, which we know as rust.
In the second stage, the control valve induces a vacuum or suction on a small line that leads to the brine tank. The salt solution or saltwater stored there will slowly pass through our water softener mineral. Now, here is where the magic begins. Our softener mineral will give up those hard ions it has captured and replace them with soft ions — the sodium from our brine. A specific amount of saltwater will bathe the mineral bed and then a mechanism like a float valve or a timer will shut off the brine. A typical 1-cubic-foot water softener will use between 6 and 15 pounds of salt dissolved in water per regeneration. For water with iron in it, the higher figure is recommended. The amount is adjustable with the control and brine valves; the brine valve being in the brine tank.
The third and last step of the regeneration is to pass a high-capacity flush of water through the mineral to ensure salt-free water goes to the tap. The softener then goes back into what we call service position and the owner enjoys another 1,200 gallons, plus or minus, of soft water. Some softeners use a meter that keeps track of the number of gallons that have gone through the unit. The meter is adjusted to the hardness of the water and can initiate regeneration. But most units use a simple time clock with regeneration taking place from one to 12 times in a 12-day period. I have much, much more to write about water conditioning, so please keep reading.
Last time, I wrote that my lawn was nice and green and I was mowing a lot. As I write this two-thirds of the way through the month of July, we have had virtually no rain whatsoever — not one drop this month. So my lawn is all burned out, as happens when the rain stops. The buckhorn is growing well. It is a nasty weed that has a single stem about 10 inches long with a bud at the top. The bud contains seeds for next year’s crop. It is unsightly and thrives on dry weather. One mowing will not kill it. I’m not sure if even four in a season will do that. Until next time. I hope your lawn is green and you can sit on it under a shady tree after a hard day’s work.
For more John Schmitt columns, visit www.nationaldriller.com/schmitt.