Cleaning the Water, Clearing the Air

How UV Water Treatment Improves Water and Air Quality

By Jeff Boynton

Swimming pools are one of the most popular forms of exercise in North America. Exercising while swimming has been long recognized for cardiovascular health benefits and fitness. However, water is how life started on this Earth in a microbial level, and that is still true today.

Many water-borne pathogens have been treated with various methods over the years. Today, ultraviolet water treatment is being discussed more and more as a valid alternative for water treatment in recreational water facilities. There is much discussion recently about the MAHC guidelines, which address many of these concerns for providing properly sanitized recreational water facilities.

As frequent reports about recreational water illness and bacteria outbreaks abound in the press, many commercial pool operations are choosing UV sanitation in order to comply with water quality testing parameters and state mandates. Some residential pool owners are even turning to UV water treatment for its ease of use, reduced chemical consumption, health advantages and environmentally friendly benefits.

UV treatment of water is a terrific way to sanitize swimming pool water, but it is also a great product to use in order to improve the air quality around swimming pools—especially indoor pools. This article will explain what UV is, which UV products are appropriate for particular pool types and sizes, and how UV can improve water and air quality in and around swimming pools and spas.

UV water treatment is based on using the power of germicidal light to disinfect water, thereby consuming fewer chemicals and allowing them to be more effective. UV-C eradicates microorganisms that pass through the UV light chamber, but it does not act as a residual. UV light technology only works on the water flowing through the light chamber; it does not work on the dead zones of the pool. Reducing chemicals means cleaner, less aggressive water that is easier to balance.

What Is UV?

Ultraviolet radiation is an invisible light emitted from the sun. More than 100 years ago European scientists from different countries discovered the top surface of lake water was sterile when exposed to sunlight. Investigation led to the discovery of ultraviolet light and to the invention of UV bulbs. Ultraviolet (UV) light is situated in the electromagnetic spectrum between X-rays and visible light. UV light is split into four main categories, UV-A, UV-B, UV-C and Vacuum UV. The area between 240 and 280 nanometers (nm) is UV-C, commonly known as germicidal light. This is the UV light that is used to sanitize swimming pool water.

How Does UV Sanitize Water & Improve Water Quality?

UV-C light has the ability to cause permanent damage to a wide variety of microorganisms in water. Certain species of microorganisms, such as the news-making protozoa Cryptosporidium, are not completely sanitized with traditional disinfection techniques such as chlorine. UV-C light is not a biocide but disrupts the micro-organism's DNA, ensuring that organisms present in water are unable to replicate and remain inert. The natural phenomenon of ultraviolet radiation is reproduced inside reactors via powerful lamps that emit germicidal UV-C radiation. All germs, viruses, bacteria, etc., are thus deactivated and can no longer reproduce. Unlike other sanitation treatments, UV does not affect the taste, color or pH of the water being disinfected.

In a UV sanitation system, the pool water circulates directly under the exposure of the UV lamp, allowing the radiation to eliminate protozoans, viruses and bacteria. UV has gained traction in part because of its ability to eliminate chlorine-resistant microorganisms such as Giardia and Cryptosporidium, which are common causes of recreational water illness and pool closures.

Although this technology has been known for a long time, since 2000 improvements have led to UV water treatment technology's use in Europe. UV light sanitation is more prevalent in Europe where it has been successfully installed in commercial pools. Many studies have been conducted proving how UV light not only disinfects but also removes chloramines. The European centers for water standards such as DWG and O-Norms have certified UV light reactors as effective in improving the quality of the pool's water and air, thereby saving valuable resources.

Choosing UV to Improve Water & Air Quality

We all know that pool water must be sanitized and clean. Pools must be treated with chemicals continuously in order to deactivate pathogenic microorganisms and to prevent the spread of waterborne illness. Unfortunately, chemicals such as chlorine react with organic and mineral compounds, resulting in harmful and smelly byproducts, among which is nitrogen trichloride—or what people commonly call 'chloramines.'

Ensuring good water chemistry is the key to maintaining a proper and safe swimming pool environment—not only to maintain a good level of oxidizers but also to correctly monitor pH, water hardness, alkalinity, etc. However, there are only a few options available to pool operators looking to reduce chloramines in their pool environments (which not only smell, but are harmful to swimmers' lungs). The five available techniques are: hyper-chlorinating, non-chlorine shocking, ozone, adding fresh water or installing an ultraviolet sanitizing system.

But before explaining these techniques, "prevention" and a "good filter" go a great way toward helping reduce chloramines.

Chloramines are produced in chlorinated water when bathers introduce ammonia and organic compounds into a swimming pool and these pollutants combine with chlorine gas. If bathers shower prior to swimming, removing body perspiration, body oils and other lotions, this substantially reduces chloramine creation but does not eliminate the issue. Making sure children use the bathroom frequently so they do not urinate in the pool can also drastically lower chloramine creation.

It is always possible to enhance the filter, such as by adding granulated activated carbon, will help remove chloramines and ammonia. Filtering is critical in pool sanitation and may require additional attention and manipulation.

5 Main Chloramine Removal Options

If you are looking to improve the air quality of swimming pools, especially indoor swimming pools, you have five main methods to reduce and remove chloramines:

1. Non-chlorine shock with mono per sulfate-based oxidizers
These products are very expensive compared with chlorine, but are strong oxidizing agents to break down chloramines when reaching breakpoint oxidation. The use of non-chlorine shock will require more intense water chemistry monitoring. And, it does add more chemicals to the water.

2. Hyper-chlorination
As a part of regular maintenance, a pool is shocked periodically to remove organic compounds, remove chloramines and free up the available chlorine to allow it to sanitize the pool. However, this also binds up the free chlorine and keeps it from performing its sanitizing function if not used in proper amounts. And, it is adding more chemicals to the water.

3. Adding ozone to the water
Ozone as a secondary oxidizer destroys ammonia and nitrogen, preventing the formation of chloramines. As a disinfectant, this technique requires a large unit to disinfect by injecting the ozone into a side stream (about 10 percent up to 25 percent of the water) and then returns it into the full flow.

4. Drain & refill water
This results in refilling millions of gallons of fresh water, which is wasteful, but also presents the new problem of having to constantly monitor the pH, temperature adjustment and alkalinity of the water—not to mention the difficulty of disposing of the water containing unacceptable levels of chemicals into sewer systems.

5. Adding a UV system
Remember that UV-C doesn't change the pH, turbidity or alkalinity of the treated water. Thus, the two main benefits to UV over the other options are that: 1) UV damages DNA/RNA at a wavelength of 254 nm so water is sanitized, and 2) studies show that both medium and low pressure bulbs decrease chloramine levels down to ranges acceptable to health organization guidelines.

Choosing the right UV System

Not all UV is the same. It is important to determine the correct sizing of the UV unit for the type of pool and its use. Water flow is a major factor in determining the size of the unit. Also, is the pool use more commercial or more residential, and what type of bather load needs to be treated? Indoor or outdoor?

Basically there are two different types of UV lamps: a low-pressure high-output lamp, which emits UV rays only at 254 nm, and a medium-pressure lamp which emits UV rays between 200 to 600 nm.

Generally low-pressure UV lamps may be better suited for residential applications, while medium-pressure models typically are designed for large commercial installations. The distinction can be chalked up to cost, flow requirements and the ability to destroy chloramines.

Due to their large light spectral (200 to 600 nm), medium-pressure lamps more effectively reduce the health problems caused by nitrogen trichloride (chloramines).

In sum, the facility usage, type of pool and bathing loads are all to be considered. For example, the needs for an indoor Olympic-sized pool with a heavy bather load will substantially differ from an outdoor medium-sized pool at a hotel. The UV technology needs to fit the environment and should be affordable so that the facility can take advantage of the benefits of UV light technology.

Key Things to Consider:

Wattage: Compare the wattage needed to attain good flow treatment. The wattage consumption between different products varies. Also, you will save more with a system that has an electric ballast, which prolongs the life of the UV bulb and uses less energy.

Spare Parts/Maintenance: Ask about spare parts pricing, which varies by manufacturer. And be sure to ask about required maintenance costs. Consider the number of bulbs in the system. Some UV systems may require substantial maintenance and require servicing for warranty program.

Cost/Payback: Notwithstanding the obvious health benefits of UV water treatment using fewer chemicals and providing a safer bathing environment, many times a UV system will pay for itself in comparison to "traditional" methods of sanitation. Depending on many variables including water quality, bather load, the facility's filter system and installation, the return on investment could be less than one year, all while providing better air and water quality. Plus you'll be able to say you are lowering your carbon and water footprint on a planet—which is good for you and planet earth!


In North America, the standard protocol for water quality maintenance (WQM) is premised on the assumption that appropriate filtration and residual halogen disinfection will inactivate all pathogens. However we now know that:

  • "Giardia can take up to 45 minutes to become deactivated in chlorine."
  • "Noro virus takes about 30 to 60 minutes to deactivate."
  • "Crypto is highly resistant to chlorine and can linger in a pool for up to 10 days."

(Refer to Inactivation time for human disease-causing microbes in chlorinated water.

Unfortunately, recreational water illness (RWI) is dramatically increasing. Research has also shown that halogen disinfection creates hazardous byproducts (DBPs). These DBPs include chloramines, THM, HAA, and other contaminates that are recognized to have serious negative health effects. It is also established that certain pathogens are resistant to chlorine and ozone, thus leading to various diseases including respiratory, skin and gastrointestinal problems. Awareness and concern about exposure to DBPs in pool and spas is increasing. Health officials have acknowledged that the increase of RWI and negative health effects associated with DBPs necessitates a paradigm shift in our thinking about how we treat pool and spa water.

Experts agree that moving beyond the basics will require revising the two pillars approach that includes filtration and halogen followed by adopting supplemental disinfection for water quality management for pools and spas.

In-line UV disinfection is recognized as an extremely effective and reliable method for deactivating pathogens in the water and reducing the bathers exposure to DBPs.

Public health authorities are already beginning to mandate supplemental in-line UV disinfection. After the Crypto outbreaks in upstate New York a few years back, the state now mandates supplemental in-line UV disinfection on all public splash parks, as do several other states, including Florida, Ontario, etc.

In some areas, chemically laden pool water cannot be put to waste as it goes directly through the aquifers and could contaminate the ground water. Water that is treated with UV light usually has drastically reduced chemical levels and can safely be drained.

Now is the time to consider a UV system to improve both the water quality and the air quality of swimming pool facilities.

Jeff Boynton is the director of Sales and Marketing for Delta Ultraviolet Solutions, based in Gardena, Ga. Delta UV provides "clean light" technology for eradication of microorganisms and chloramines removal for swimming pools and spas. For more information, visit

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