Water Conditioning & Purification Magazine

Well Water Chlorination: An Effective, Low-Cost Source Remediation Device

By Karlis Bite

Proper Disinfectant Dispersal: How does it work?

The jet device for chlorine injection and dispersal discussed here is very simple to use. You simply fill the canister with disinfecting agent (unscented liquid chlorine bleach), attach a household garden hose and, for dug wells, lower the entire unit into to the well using the hose.

As you reach the surface of the water, turning on the garden hose causes the unit to pressurize. When adequate pressure is reached, the unit begins to spray the chlorine as you slowly lower the unit to the bottom of the well. Eight specially arrayed pressure jets ensure even dispersal of the disinfecting agent throughout the entire volume of the well, and guarantee contact with the entire body of water and well casing.

In the case of drilled wells, the entire unit isn’t lowered into the well—most drilled wells are too narrow to host the canister. Instead, a discharge hose attachment was developed with a pressure jet assembly at the tip. The hose is lowered to the well bottom while the cylinder housing rests on a custom stand beside the well. The length of the hose is customized to the depth of the well. The discharge hose is lowered to the bottom of the well casing by either removing the well cap or through the vent hole in the drilled well’s seal. Once again, the unit is activated by turning on the water supply and slowly pulling the hose out of the well. The result is an even dispersal of the disinfecting agent throughout the entire well.

Summary: During May/June 2000, the water supply of a rural Canadian town became contaminated with E. coli bacteria. Seven residents of Walkerton, Ontario, died and over 2,300 townspeople became ill. Drinking water quality, on the sideline of public health concern due to budget cuts and an alarming complacency, now became a critical issue.

Across rural Canada, as thousands of private well owners began regularly testing their water in government laboratories, the magnitude of the water quality crisis came into focus almost as soon as the E. coli contamination and ensuing deaths and mass illnesses in Walkerton, Ontario, Canada, became front page news.

In Grey-Bruce County, where Walkerton is located, over 29,000 water samples were submitted to the public health laboratory during the months of June, July and August of 2000, and the results were disturbing. Tests showed that over half of all rural wells were contaminated with unacceptable levels of coliform bacteria and one in 10 contained traces of the E. coli O157:H7 bacteria that was behind the Walkerton tragedy.

Calling in the cavalry
A company was formed in Kincardine, a small town not far from Walkerton in October 2000, to develop a solution to the serious water contamination problem facing rural well owners.

Like thousands of other farm owners, Henry Bandomir—a retired Ontario hydro construction equipment superintendent and engineer by trade—tested the water on his farm 15 miles north of Walkerton. He found unacceptable levels of coliform bacteria in his 40-foot dug well. At first, he had no interest in starting a business. He simply wanted to clear the harmful bacteria from his well. Like many others, he turned to his local public health unit for help.

The public health officials at the unit instructed Bandomir to apply a prescribed amount of chlorine bleach—depending on the volume and depth of the well—stir it, run the taps until chlorine could be detected, then leave it overnight. After several attempts, he found it impossible to achieve a zero bacteria count using this method.

Drawing on his engineering background, Bandomir studied the problem at length and discussed it with health officials, determined to find a solution. He became convinced the answer was to somehow disperse the required amount of chlorine evenly throughout the entire body of the well, especially below the suction line where the water is drawn into the house. This would ensure the disinfecting agent reached every part of the water supply system, where it would remain overnight.

The first draft
His first prototype consisted of a stainless steel container—modified with a coupling for a water hose connection and a discharge nozzle with eight holes at the bottom of the unit—designed for an even 360-degree dispersal. The unit was filled with the required amount of chlorine and lowered to the bottom of the well. Once there, the hose connected to the unit was turned on, forcing pressurized chlorine from the container into the well. This early prototype unit produced encouraging results, but production costs were prohibitive.

At this point, with a partner now on board, the team quickly realized this was a product that could help all those desperate for safer water, and quickly set out to develop the invention. It was decided that plastic was the ideal manufacturing material. The device underwent extensive testing and numerous transformations to improve its performance and make it easy to use.

For drilled wells
A method also was devised for treating drilled wells just as effectively as dug wells. In this case, a special hose with a custom discharge jet at the end would be lowered into the well through the vent hole in the drilled well’s seal or by just removing the cap. With the help of water pressure from a common garden hose, fed into a stand-mounted unit at the side of the well, chlorine bleach would be forced down into the well and dispersed.

During each step of the development, public health inspectors at the local health unit played an integral role. Harold Rankin, a retired county health director who was called back into service to help deal with the Walkerton water crisis, and Kathy Cassidy, a local public health inspector, gave valuable input to the project. Government guidelines for well safety were followed explicitly in developing the system.

The simplicity of the design deems it useful anywhere bacterial contamination of well water is a health hazard. Treatment can be administered safely and inexpensively, and easily incorporated with other water purification methods. The company hasn’t developed a radically “new” technology, but simply enhanced the effectiveness of an already proven method, which is superchlorination or “shocking” of well water. This is the universally accepted method for dealing with bacterial contamination and is recommended by many public health officials.

Filling in the details
Health Canada reported in What’s in Your Well: A Guide to Well Water Treatment and Maintenance: “Add the amount of unscented bleach to the bottom of the well and then agitate the water.” The problem is, it doesn’t say how one is supposed to apply the bleach to the bottom of the well and agitate a body of water that may be 20 or 30 feet deep in the case of dug wells, or 100 to 200 feet deep in the case of drilled wells. It’s imperative the disinfection agent is dispersed evenly throughout the entire body of water for it to achieve sufficient contact time to eliminate the bacteria. Simply pouring the bleach into the well cannot guarantee desired results.

The unit has been designed to be used in conjunction with regular testing of the well water (three sets of three samplings taken over a period of six weeks), as recommended by the Ontario Ministry of Health and Health Canada. If lab testing isn’t available, as it is in Ontario, inexpensive test kits are available for onsite testing of well water. If the test indicates harmful bacteria, the well should be treated and another water sample should be taken after 48 hours. Even if the contamination is cleared up, the well owner should still take two more samples spaced a week apart before drinking the water, and then resume regular testing in four to six weeks.

When first performed, the procedure usually requires two to three treatments, spaced a week apart, to clear up a bacterial contamination problem. Contamination of the groundwater and the well often occurs after spring runoff or periods of extended drought or rain. Water should be tested for bacteria at these times in particular. If bacterial contamination is a recurring problem, steps may have to be taken to repair the well seal or other parts of the water supply system. Faulty septic systems have been linked to well contamination, especially if the septic tank is too close to the well. If no testing of any kind is available, regular treatment of the well (once every two weeks) can greatly reduce bacteria in the water. The unit can also be adapted to use compressed air or carbon dioxide (CO2), if water pressure isn’t available.

Since the unit has a five-liter capacity, deeper dug wells and new wells may require more than one application. Once the chlorine is dispersed, simply run household taps until chlorine is detected, then leave the chlorinated water in the household plumbing overnight to kill the bacteria in the water lines. Run the taps again the next day to flush out the chlorine solution.

The deep well dispersal chlorination unit described here offers a simple cost-effective tool that could be used as part of a multi-barrier approach to drinking water treatment.  

The development team spent a good part of the summer of 2001 conducting field testing across the county and the results were outstanding. In almost every case, all traces of coliform—particularly E. coli O157:H7—were eliminated with the device. And with some 16 million private wells in North America alone, the market is definitely there to be tapped.

In war-torn or developing countries, where alternate water treatment technologies are unavailable or impractical, a low-cost device such as this could be made readily available as the first line of defense against waterborne pathogens.

About the author
Karlis Bite is vice president of Cleanwell International. The device discussed in this article is Cleanwell’s Jet Chlorinator, which comes in two forms—a canister unit for dug wells and a canister with a discharge hose attachment. Bite can be reached at (519) 241-8043, or email: kbite@rogers.com, website: www.cleanwell.ca

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