Vitamin C for Chlorine Removal


Vitamin C was originally discovered and selected as our utility’s chemical of choice in 1989 at the suggestion of a kidney dialysis physician1 who furnished medical references for this author to review. Since the use of vitamin C was documented to be an effective technique, preparations were taken to adapt this method into the waterworks field. The Public Utility District of Skagit County is believed to be the first utility to use vitamin C to neutralize chlorinated water in order to protect fish during large-scale flushing operations.

In the beginning, there were few reasons to select vitamin C, other than the fact that it was recommended by a medical professional. Since then, the author has realized numerous new reasons for choosing ascorbic acid to dechlorinate water during flushing operations. What follows are some of them.

Vitamin C boosts the fish’s immune system.

It was not an easy task to find a source for ascorbic acid at a reasonable price or as a powder ready to mix with water. While placing the initial order, the sales representative commented about the large quantities that he also sells to manufacturers of fish food pellets used at fish hatcheries. It turns out that vitamin C is an essential nutrient for fish and actually boosts their immune system. It is essential for their life, and hatchery trout develop cataracts without vitamin C in their diet.

Vitamin C is environmentally logical.

Environmentally, it makes good sense to use a reagent that is beneficial to fish (by strengthening their immune system) to eliminate a deadly pollutant that will kill fish at very low doses (0.011 milligrams per liter chronic level). Use something good to remove something bad. Not only do fish benefit, but all forms of biodiversity found in streams and lakes become stronger and suffer less routine physical distress with increasing levels of vitamin C. Fish have been found to be attracted to it.

Ascorbic acid is comprised of hydrogen, oxygen, and carbon, which after chlorine neutralization, results in a milder and safer reaction consisting of inorganic chloride and dehydroascorbic acid2. The latter byproduct is still a nutritional benefit to living organisms. If ammonia is present in the water to be treated, as found in chloraminated water supplies, another byproduct, ammonium chloride, can be detected. (Ammonium chloride from chloraminated water supplies is thought to be a byproduct with all chemical dechlorination reagents.)

Sulfur-based byproducts that are produced during dechlorination, other than hydrochloric acid, are not commonly known.

Vitamin C is a proven reducing agent.

The Environmental Protection Agency published a report3 in 1989, which listed ascorbic acid as a dechlorination reagent worth considering. Today, water-testing laboratories use ascorbic acid to quench chlorine from a field water sample, which has been drawn for VOC testing at a distant laboratory.

The medical field has used ascorbic acid to neutralize chlorine since the early 1970s. Free chlorine and chloramines were found to destroy the reverse osmosis membrane used during hemodialysis. Today, many doctors prefer large carbon block filters to remove chlorine prior to kidney patient treatment.

Recently, water utilities have also demonstrated effective results in the field. In December of1998, AWWA’s monthly publication, Opflow published an article4 on early vitamin C technology.

A recent American Water Works Research Foundation (AwwaRF) study5 documented the effect of various compounds on oxygen levels. Their findings, which were based on field measurements, indicated that water treated with vitamin C somehow increased the oxygen levels of the sampled water. While this cannot be accepted as the norm, it does reveal that vitamin C imparts less of an effect on oxygen levels when compared to the other sulfur-based reagents that were included in the study.

There is more to vitamin C than ascorbic acid.

The most cost-effective form of vitamin C is in the form of pure ascorbic acid. Vitamin C can also be purchased as sodium ascorbate. Certain utilities prefer sodium ascorbate because of its higher pH. Sodium ascorbate has a pH of approximately 7.8 while compared to ascorbic acid, which yields a pH of approximately 3. Utilities with poorly buffered supplies have noticed a slight decrease in pH when using ascorbic acid, whereas upon switching to sodium ascorbate, no pH drop was detected.

Sodium ascorbate is slightly more expensive than ascorbic acid and approximately 11% more is required to match the same effectiveness of pure ascorbic acid.

The shelf life for vitamin C is reported to be in excess of one year if kept in a dry, cool, dark storage area.

The most common question asked is where vitamin C can be purchased. Integra Chemical6 (800-322-6646) will provide small samples (150 grams) for testing purposes as well as sell multiple 55 pound boxes of pure ascorbic acid. They are experienced with vitamin C technology.

Expense is justifiable.

Many water utilities have documented an inactivation ratio of 2.5:1, which means that 2.5 pounds of ascorbic acid is necessary to neutralize one pound of chlorine in solution. (The ratio, which contained in the AWWA Opflow publication4, has not yet been duplicated in the field.) Perhaps the effectiveness and efficiency of ascorbic acid is dependent upon pH or other factors. The author desires to receive feedback from future ratio research.

The overall expense of using vitamin C is justifiable when all factors are considered. Utilities are finding that the expense is negligible when all risks and consequences are factored into the flushing operation process.

Vitamin C is simple to use.

There are numerous methods for applying the vitamin C solution to a stream of chlorinated water. The simplest method is to drip a prepared solution of at least one percent solution (by weight) of ascorbic acid into an open channel condition, such as a ditch or curb. On the other hand, large utilities have elected to build a mobile trailer that can be driven to the site, although these have fallen out of favor with newer options now available.

Today, there are numerous manufacturers of high quality injection devices, which can dechlorinate large flow rates from a fire hydrant. The author collects information on these devices, most of which were nonexistent a few years ago. offers the largest selection of these devices available to the water industry. Vitamin C in the form of a large tablet6 is also available.

The chemical rate of reaction for vitamin C is significantly faster than sodium thiosulfate. Because of sodium thiosulfate’s slow reaction rate, QA/QC testing must take place “further downstream”. Upon collection of a field sample, sufficient time is required to verify inactivation. During this time, a significant amount of improperly treated water can be released. The reaction time for vitamin C is nearly instantaneous, and it can therefore be quickly verified at the point of discharge.

Vitamin C is safer than sulfur-based reagents.

Some dechlorination reagents can act as a respiratory irritant or can otherwise be toxic to waterworks operators. Still other reagents are reported to scavenge oxygen from the treated water, that defeats our main objective, that of protecting fish from water utility operations. Current findings5 indicate that vitamin C is less of a concern in these areas. Vitamin C is the only reagent with an NFPA rating of 0,0,0.

Formal research7 has shown that live catfish can tolerate high doses of vitamin C beyond 3000 ppm for 24-hour duration. (It should be noted that during these experiments air was bubbled through the water, apparently removing concerns about depleted oxygen levels at such high levels.) Each utility must carefully consider the above statements, since no one has yet determined the amount that can eventually begin to harm fish.

As far as humans are concerned, vitamin C is now available as a NSF (National Sanitation Foundation) certified antioxidant (in both forms) for human consumption6. The City of Lacey, Washington is the first water purveyor to capitalize on this certification by incorporating vitamin C into their routine water treatment process. Lacey uses it to lower chlorine levels following iron/manganese treatment that requires chlorine to facilitate the removal of those inorganic compounds. Their past water quality record has allowed Lacey to avoid chlorination altogether. Their chemical cost is estimated (by the author) to be approximately $25 per million gallons, or only about $50 per day. Lacey officials prefer vitamin C to any other sulfur-based reagent.

Public perception of vitamin C is favorable.

The public is somewhat familiar with vitamin C, but they are unfamiliar with sodium thiosulfate and sulfite compounds. Vitamin C is found naturally in most fruits and vegetables, and some individuals even consume 2 or 3 grams of extra vitamin C on a daily basis for health purposes.

In general, vitamin C has received excellent press ratings ever since Linus Pauling earned his first Nobel Peace Prize for his research. He personally consumed over a pound of sodium ascorbate each month.

There are other uses for vitamin C.

Ascorbic acid has also shown itself an excellent manganese stain remover, especially for tank interiors and customer laundry problems caused by manganese. Design engineers protect sensitive deionization resin beads and reverse osmosis membranes by using vitamin C. It also has been investigated as a simple means to quench unused ozone at ozonation generation facilities.

Authorities are comfortable with vitamin C chemistry.

In general, environmental authorities are intrigued with ascorbic acid. After all, it removes chlorine effectively as documented by the EPA and it boosts the fish’s immune system. When compared to sulfur-based compounds, vitamin C seems to be compatible with their thought process and beliefs. Furthermore, it is a nutrient that fish require to aid them in the healing process after sustaining an injury.


As with any chemical process to neutralize chlorine, it is imperative to verify and monitor effective and continuous dechlorination. Underdosing and overdosing with any chemical can cause injury to aquatic life. It is important to note that the target chlorine dose can vary over time, especially when dechlorinating a new water main disinfected with calcium hypochlorite tablets or granules during pipe installation. It is also important to document each dechlorination event for operational and legal reasons. Be prepared for under-treatment emergencies by having a portable means to add additional reagent to the yet chlorinated stream of water.

Additional hazards to fish can exist. It is also important to minimize turbidity or suspended solid concentrations when flushing. Even the amount of time taken to shut down the flushing operation can be injurious to fish due to the “stranding” of fish in pockets or pools that did not exist when the flushing operation began.

Make certain that you have obtained permission from the appropriate authorities to use vitamin C or any other reagent. It may not be approved in your area. Obtain all necessary permits in advance. Evaluate other reagents and other procedures. Seek help when starting any dechlorination program. Study the MSDS for every reagent.


Many professionals feel that vitamin C offers a new and effective option for waterworks operators who will be dechlorinating more often than in the past. Additional research is needed to define the total impact on aquatic life from all dechlorination compounds, including vitamin C.

Vitamin C technology is logical from an ESA perspective. It is possible that vitamin C will soon be recognized as the best method, and perhaps, the only method, for neutralizing halogens.

Please share any pertinent findings that you may uncover while carrying out chemical dechlorination. The author is anxious to hear about your ideas and findings. They can be forwarded to the author at


1 Doctor Thomas Sawyer, MD, former Director, Northwest Kidney Center, Seattle, Washington

2 Ward, David M., “The Use of Ascorbic Acid in Water Treatment For Hemodialysis” Contemporary Dialysis & Nephrology, page 33

3 Warner, Susan C., “Surrogate and Matrix Spike Recoveries in Chlorinated Samples Using Sodium Thiosulfate, Sodium Arsenite and L-Ascorbic Acid as Dechlorinating Agents”, Environmental Protection Agency, Publication number EPA-903/9-89-001, 1988

4 Peterka, Greg, “Vitamin C A Promising Dechlorination Reagent”, Opflow (Vol.24 No.12) December 1998, Pg. 1, American Water Works Association

5 Tikkanen, Maria, “Guidance Manual for Disposal of Chlorinated Water” American Water Works Research Foundation, Denver, Colorado, AWWARF Project #2513, Publication number 90863

6 Burg, Paul, Director of Research, Integra Chemical Company, 710 Thomas Avenue SW, Renton, Washington 98055, 800-322-6646,
7 Thed, E.T. “Ascorbate Absorption By Live Channel Catfish as a Function of Ascorbate Concentration, pH, and Duration” Journal of Food Science, 58(1): 75-78


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