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Purification of
Cistern Water by
Insitu Ozonation

Ozone purifies water without producing any adverse by-products
due to four unique properties.

1. Ozone is the second most powerful oxidizer, falling only behind Fluorine. Therefore it has the power and ability to destroy all types of microorganisms. In fact, no microorganism is known to be resistant to ozone.
2. Residual amounts of dissolved organic compounds can be removed by oxidation.
3. Ozone is a very unstable molecule which will, in water, very rapidly self-decompose into oxygen from which it was formed and leave no hazardous by-products as does chlorine, the most widely used oxidizer.
4. Residual amounts of ozone can be removed from the water prior to consumption by passing the water through a UV chamber, and/or an activated charcoal filter.

Villa Delicia
       Heavy microbial contamination can be removed from water through either ultrafiltration (Including reverse osmosis), resin absorption, pasteurization, or UV light irradiation. However, the last traces of soluble organic contaminants can not be removed by either of these processes. More importantly, pathogenic microbes can recontaminate water that is stored in tanks or cisterns. As water quality has declined, more and more chlorine has been added with the resultant water being almost unusable due to taste and odor.

At Left: Home Equipped with Chem-FreeTM
Water Quality Assurance System

Furthermore, the by-products that result from excessive chlorination are toxic and some are listed as carcinogens. The EPA has identified Trihalomethanes, that result from the partial oxidation of organics by chlorine, as the number one contaminant to be removed from America's drinking water. There are also studies that link the increase in bladder cancer in men to long-term consumption of chlorinated water. The increase in bladder cancer rates in the US exactly tracks the increase in chlorination of municipally treated water over the past seventy-five years.

       E-Coli is used as an "Indicator" bacteria, that very accurately predicts the presence of other pathogens. The rate that E-Coli bacteria is killed when exposed to ozone has been demonstrated to be 3125 times faster than that shown by chlorine. Therefore, considerations of contact time between water and ozone is reduced to the time necessary to achieve a concentration of 2 to 3 PPM (Parts Per million) in the treated water. Some microbes require hours of contact time with chlorine. Some pathogens such as Cryptosporidium are not totally eliminated by chlorination. More importantly, the survivors viability is not impaired in the least by passage through a chlorination stage. This organism caused 140,000 cases of illness and 112 deaths in Milwaukee, Wisconsin, when it was washed by heavy rains from stock pens and into the water treatment system. Ozone is recognized as the number one weapon against Crypto.

       A properly designed and sized "Point-of-Entry" ozonation system installed in the supply water piping system will totally remove any concern about the purity of water taken into a home. Alternatively, a Chem-Free, "WQA"ú (Water Quality Assurance) system will deliver controlled and timed amounts of ozone directly to the cisterns. An ultraviolet irradiation unit, and/or charcoal filter should also be installed in the output line from the cistern and before the distribution system to remove residual ozone from the water before use. Although the presence of residual ozone in the water is totally safe, the odor of ozone from the water may be objectionable to some people as ozone is detectable at levels as low as 0.0025 PPM.

       Ozone is used by water bottlers to ensure complete disinfection of the bottle and cap after the bottle is sealed for shipping. Breweries use ozonation to remove odors and taste from water used for making the beer. Ozone will also very effectively eliminate the "Sulfur" odor and taste that is common in coastal well water. Removal of Iron and manganese will also be facilitated by the presence of ozone.

       American municipalities, such as Los Angeles, San Diego and Costa Mesa, California, that have begun using ozone in the water treatment plants are reporting good results and are quite satisfied with ozonation. That would not be much of a surprise in Europe, as Nice, France has been using ozonation in the municipal water treatment systems since 1906. Costa Mesa, CA is tapping into a ground water supply that was, for all intents and purposes, unusable without ozonation. Ozonation is better, cleaner, safer and not damaging to the water system, nor the people who have little choice but consume the water therefrom.

       Water that is stored in a tank or cistern can be contaminated through numerous vectors. The easiest entry point, other than pathogens introduced along with the water, is the vent. Even the very pure water produced by a "Reverse Osmosis," or RO system will become contaminated if steps are not taken to ensure its continued purity. Cisterns, especially those that collect rain water from roofs and other structures, are becoming increasingly suspect in the transmission of pathogens.

The most popular methods currently in use in an attempt to maintain water quality are:

  • Chlorination
  • Bromination
  • Ultraviolet or "UV" sterilization
  • Ozonation

       Chlorination and/or Bromination involve the addition of either of the two disinfectants. Both chemical are deadly poisonous in very low-level concentrations. Chlorine and Bromine are treated as hazardous material either in transit or storage. The addition of the chemicals may be under automatic or manual control. There are numerous automated and manual monitoring, sampling and control systems on the market. However, many holding tanks in the marine and maritime trades are disinfected by simply pouring Chlorine bleach directly into the tank and hoping for the best, while using the bleach odor from the water as an indication that enough Chlorine is present to do the job. Such methods evolved long before health concerns were raised about excessive amounts of Chlorine and its by-products being present in the water we consume. A direct link has been established between bladder cancer and the consumption of Chlorinated water. The only unique, and valuable property of Chlorine in water is its ability to provide "Residual" sterilization between the treatment plant, and the point where the water is consumed. It should be relegated to that role as soon as possible.

       UV sterilization relies on the well-known fact that UV radiation will destroy the DNA of any living organism. The mutation of our skin's DNA by sunlight is the primary cause of skin cancer. Unless a sufficient amount of UV power is delivered for a minimum time period, expressed in "Watt-seconds," a pathogen will not be destroyed. UV sterilization of water is never 100% effective due to the necessity of getting sufficient short-wave, or "Germicidal" UV radiation into the subject microbe. If the water to be sterilized is not perfectly clear, it is impossible to apply enough UV energy to get the job fully accomplished. Furthermore, if all of the microbes are not within a short distance of the UV light, the diminished intensity of the UV light, due to its passage through the water, renders it ineffective.

       Another factor is time spent in front of the UV lamp, which is the second part of the "Watt-second" equation. The correct term is "Dwell-time," which means that if the GPM, or Gallon Per Minute flow rate is only slightly too high for the power of the UV lamp, there is little net effect on the microorganisms one wants to eradicate. One more very often overlooked problem with UV sterilizers is the absolute necessity of replacing the bulb on a regular schedule. UV bulbs are actually Mercury Vapor Arc Lamps, which start to deteriorate from the moment they are turned on. After 18 months of service, they emit very little of the short wave, or "Germicidal" wavelength UV radiation that is necessary to kill pathogens. No short wave UV, no germicidal action, simple. For that reason, one should never trust a UV sterilizer to do the unless the replacement date is written or otherwise indicated on the unit. The main limitation of UV sterilization, is that even under the most ideal conditions, a UV sterilizer is about 85% to 87% effective at its absolute best level of performance when new, with a steady and measurable decline over time.

       OZONATION, or the injection of ozone into water. There are several methods whereby ozone and water may be brought into direct contact. Regardless of the methodology, ozone is still the most effective disinfectant known for water intended for many uses, human consumption in particular. Ozone is the preferred disinfectant of water in France, as well as several other European nations and interestingly, Singapore, where ozone is uses for the primary oxidizer. The one limitation to the exclusive use of ozone in municipal potable water treatment is that it is not very soluble in water. That is the reason that ozone does not provide a "Residual" disinfecting power all the way to the end of the pipeline in a distribution system that may stretch for many miles. Chlorine on the other hand, is very soluble in water. Therefore, very small amounts of chlorine is still used to provide the residual sterilization all the way to the consumer. The good news is that when ozone replaces chlorine as the major oxidizer, ninety-five percent less chlorine is needed. As a result, Chloramines such as chloroform, as well as THMs (Trihalomethanes) are not produced in quantities that present health concerns.

        The CHEM-FREE Water Quality Assurance System is designed to work with fresh water only, as ozone can not remove salt from water in order to make it fit for consumption. Our only concern is insuring the purity and potability of water stored in holding tanks of any form, and cisterns. We call it a Water Quality Assurance System because that is the precise function it is intended to perform, keeping potable water as pure and safe as the consumers thereof expect it to be.

       Ozone was first used in water treatment in Nice, France in 1906. The only reason that ozone has not totally replaced chlorine in municipal water treatment is its low solubility in water, and therefore its inability to provide a "Residual" disinfection power all the way to the opposite end of the system in a municipal application. However, ozone can be used as the primary oxidizer or sterilizer on the front end of the treatment system, where it can reduce the amount of chlorine required by 85% to 90%. At that point, a small residual of chlorine can be added to the very pure water at the treatment and distribution point to insure purity all the way to the consumer. In a marine application, or for that matter a home, ozone can be used to make great improvements to the water, in addition to insuring the purity thereof.

       There are several methods of injecting ozone into the water. The simplest method also happens to be the most efficient. A ceramic or other style of diffuser can be as much as 90% efficient in getting ozone into water.. Ozone is delivered through a tube, stainless steel, TEFLON, PVC or other material, under slightly elevated pressure sufficient to overcome the water's standing head and the diffuser's restriction, and into the diffuser. As it emerges from the diffuser, the ozone forms bubbles, the smaller the better, as it flows into the water. Ideally, five feet is the minimum depth of water needed to insure full efficiency of the diffuser system. For standing heads of less than five feet, ozone has very little time to diffuse into the water to be treated, so longer run times, or greater amounts of ozone will be required.

       Another commonly used method is a venturi type injector, or "Eductor" as it is sometimes known. This method uses a well understood physical phenomenon of a pressure drop occurring when a fluid is forced to increase its velocity when being forced through a restriction. Conversation of energy laws means a reduction in pressure results from an increase in velocity right at, or immediately after the point of restriction in the line. When a port is provided at that point, a partial vacuum is created. The resulting vacuum will allow a higher pressure, either atmospheric or above, to push another fluid through the port and into the fluid stream passing through the restriction. The most well-known application of the venturi is a carburetor for an internal combustion engine.

In the case of a Chem-Free venturi type injector system, three pump locations are employed, the selection of which is determined by the application or treatment method. They are as follows:

1.   The primary type is a submerged pump/venturi unit is placed in the tank or cistern to be treated. The venturi is located on the pump outlet, the ozone tube attached to the venturi vacuum port, and the pump is powered by the Chem-Free WQA Control System.

2.   The second type is known as a "Side-stream" type. In this instance, a pump is located outside of the tank or cistern to be treated. Water is pumped through the side stream venturi, which functions as above, and returned to the tank or cistern.

3.   The third type uses the primary system water pump. In this case, a venturi injector is added to the pump output line, and before the distribution or storage system thereafter. This is the less preferred type, as it necessitates sizing the venturi according to the pump capacity and flow rates, which may not necessarily be convenient for the application of a Chem-Free venturi device.

       OZONE DESTRUCTION after the injection device or system may be necessary in some applications. If the water is routed directly into a distribution system, it is necessary to remove, or otherwise destroy any residual ozone entrained in the water. The ozone will not present a health risk if it is consumed in the treated water. ozone will however, outgass from the water, and impart an unusual and possibly objectionable taste if it is not destroyed.

There are two primary methods of removing or destroying ozone in water:

       Ultraviolet Radiation will destroy ozone in water. By connecting a UV chamber in the water line at some point after the pump and before the water enters the distribution system. There are numerous styles and designs of UV chambers for water purification. The main point to consider is the flow rate. The destruction of ozone with UV radiation does not require dwell times as long as those required for disinfection. However, it is still good to use UV disinfection flow rates of a given chamber in determining the correct power and flow rates in a UV system used for ozone destruction.

       Activated Charcoal filters will also eliminate traces of ozone. It is critical to size the system in accordance with anticipated flow rates for the system in which the charcoal filter is to be installed. An activated charcoal filter will also serve as a final "Polish" for the water prior to its passing into the distribution system. An ozonation system, followed by a UV unit and/or a charcoal filter will insure the purest and best tasting water possible.

       Iron and manganese will be removed by ozonation due to its Micro-flocculation properties. Flocculation refers to the clumping together of material, and originally referred to wool. Materials suspended, or in solution with water is easier to filter if it is "flocculated" by a material that causes the process to be initiated. Ozone is known as a "Micro-flocculent" due to its action on some minerals and other materials. Metals such as iron and manganese form into larger clumps in the presence of ozone, and will therefore will be easier to trap in a filter.

       For a number of reasons, ozone is by far better than any method of insuring the purity and safety of water stored in cisterns. It is especially true in the case of rain water that is naturally collected from surfaces exposed to environmental contaminants, and especially pathogens deposited by animals, especially birds. Any deposit left on the collection surface that must be exposed to the open air, will find its way into the cistern the very instant there is rain falling on that surface. Chlorine or bromine are problematic for many reasons including transportation and storage. Ozone does not have such problems as it is not stored, in fact ozone can not be generated and stored for later use. In all applications, regardless of type, ozone is generated on-site as it is needed.

© Chem-Free Purification Systems, Inc.

Phone: 940-627-7879
Fax: 940-627-6406
P.O. Box 59
Decatur, TX 76234

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