The Misunderstood Chemical

Chlorine’s use is extremely popular in the groundwater industry, but it is also often misused too.

By William Wagner

Chlorine is a standard chemical in the water well rehabilitation arsenal. Yet it remains largely misunderstood—and, thus, misused—by some water well contractors.

For starters, chlorine is not everything we think it is. Take it from Kevin McGinnis, president of Cotey Chemical Corp. in Lubbock, Texas, and an expert on the sanitizer.

“Probably the biggest misconception about chlorine use in a water well is that it is a great well rehabilitation chemical. It’s not,” says McGinnis, a 26-year veteran of the water well industry.

“The most common plugging issue in water wells is what we call ‘the hard stuff,’ which is the calcium carbonate, iron oxide, etc. We know that chlorine is an oxidizer, so it does not dissolve hard stuff in the well. We also know that chlorine is very inefficient at removing the soft stuff in the well, such as slime or biofilms produced by bacteria. The molecular structure of chlorine does not allow it to penetrate and disperse the slime, and so it’s not exposed to the very bacteria it’s designed to kill.

“So, if chlorine does not dissolve the hard stuff and does not penetrate and disperse the soft stuff in a water well, the reality is it has very limited use in water well rehabilitation.”

What then is the appeal of chlorine? Primarily, it’s an affordable and relatively simple way to address some of the problems that might ail a well—at least in the short term.

“Some of the advantages of most chlorine products is that they are relatively inexpensive, easy to find, and easy to handle,” McGinnis says. “Another advantage is that chlorine products are great at killing planktonic bacteria. Planktonic just means bacteria that are floating, drifting, or free-swimming in the water.”

Furthermore, chlorine continues to evolve. With sophisticated chlorine-type products hitting the market, the chemical seems certain to become a bigger part of the water well industry in the coming years.

One of the new chlorine-type products is sodium dichloroisocyanurate dihydrate. It is a chemical compound used as a cleansing agent and disinfectant and is quickly becoming a substitute for calcium hypochlorite used for swimming pool disinfection. It is also the base chemistry in Jet-Lube’s Sterilene and Cotey Chemical’s Wel-Chlor PLUS.

Another interesting disinfecting chemistry is peroxyacetic acid.

“The future of chlorine-type products looks bright when we consider the synergies we create when combining certain chemistries,” McGinnis adds. “A few interesting products might have some use in the water well industry.”

In the meantime, there are steps contractors can take to make the most of chlorine. Here are some tips to keep in mind.

More Is Not Better

There is a temptation to overtreat a well with chlorine. Shawn Lyons of Lyons Well Drilling in Stockton, Illinois, stresses that contractors should keep this urge in check.

“The general population out there—and this goes for contractors, homeowners, realtors—thinks more chlorine is better, like throwing in four pellets as opposed to two,” he says. “In this case, more can be worse. You reach a certain point where you put so much chlorine into the well that the pH has literally turned itself into a chlorine bath.

“What should only take 24 to 36 hours to pump off won’t get rid of it. You could spend up to four days pumping nonstop to get rid of it. You put so much chlorine into it that it has saturated the groundwater table.”

Chase the Chlorine with Water

Among other things, this ensures the chlorine will be distributed properly in the well.

“Most people have learned that when you put the chlorine into the well, it’s best to chase it with water,” Lyons says. “I stick a hose in there. The hose recirculates the water. Instead of dumping that chlorine into the well where it’s only going to cover a certain amount, it’s constantly mixing it. Plus, it’s chasing all the garbage that’s built up in the borehole itself.”

Understand Exactly When to Chlorinate a Well

Timing is everything here. Consider these words of wisdom from McGinnis:

“If the well is full of organic plugging issues, those need to be removed from the well before the chlorine application. Once the well is clean, it’s almost time to chlorinate.

“First, however, I recommend that the items that were pulled from the well in order to clean it more thoroughly—the well pump, pipe, and wire—be placed back in the well.

“The reason for this is that those same parts, which have probably been left lying around in the field, on the bed of a trailer or on the shop floor, have potentially been contaminated. If they’re placed back in the well after the well has been chlorinated, they potentially re-contaminate the entire well. Replacing those items in the well and then chlorinating the well helps ensure it is free of bacterial contamination.”

Chlorine Is Not Like a Twinkie

In other words, chlorine has a limited shelf life. If you use chlorine that has been gathering dust on a shelf, you’re wasting your time, effort, and money.

“Chlorine has a very short shelf life—not many people know that,” Lyons says. “The average shelf life is, I believe, six months. And that’s from the date of manufacture. It has to get loaded on a truck and sent to a distribution facility. From there, it goes to a warehouse and then a store.

“By the time it actually ends up on a shelf for sale, you’ve got about three weeks of it actually being full strength. And full strength is already diluted down. After three weeks, it drops by, like, 20 percent in its acidic amount.”

Remember—Always Remember—Chlorine Is Not a Cure-All

This is the golden rule when it comes to chlorine, so it’s worth stressing again.

“It’s important to know that chlorine is not a long-term solution,” McGinnis says. “Chlorine only kills bacteria while in contact with that bacteria. Once the pump is turned on, the chlorinated water is pumped from the well and fresh bacterialaden water replaces the clean water. These new bacteria immediately begin to recolonize the well, and problems begin all over again.

“Some in the industry refer to chlorinating a well as a ‘snapshot’ of disinfection. This is one reason we encourage well owners to begin a maintenance program for all their water wells.”

William Wagner is an award-wining writer, editor, and project manager for Wagner Communications. He has written for magazines, newspapers, books, and websites. He lives in the Chicago area, and can be reached at