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Cryptosporidium & Giardia Barrier

Municipalities around the world install TrojanUV systems to help safeguard their drinking water against chlorine-resistant Cryptosporidium and Giardia

About Cryptosporidium

  • Cryptosporidium is a protozoan that causes a diarrheal illness called cryptosporidiosis
  • The parasite is transmitted by cysts that, if ingested, can result in an infection
  • Infection is typically short-term, but can cause severe illness and even death in some individuals

Once a person is infected, the parasites proliferate in the intestine and in some cases in the respiratory tract. The infection can last over two weeks and even longer for immunodeficient individuals.

In 1993, over 100 people died and over 400,000 developed gastrointestinal illnesses as a result of a Cryptosporidium outbreak in the drinking water supply of Milwaukee, Wisconsin.

After the Milwaukee outbreak, many water treatment plants installed UV in order to meet the USEPA Long Term 2 Enhanced Surface Water Treatment Rule, since Cryptosporidium treatment was required.

UV Disinfection as a Cryptosporidium Barrier

Cryptosporidium is resistant to chlorine, but has been shown to be effectively inactivated with UV disinfection. Relative to other treatment technologies, such as ozone and membrane filtration, UV offers a cost-effective solution for Cryptosporidium inactivation.

UV in Action


Surface Water Treatment & LT2 Rule Compliance

The White Tanks Regional Water Treatment Facility is located in Surprise, Arizona, and treats surface water from the Colorado River that is delivered by a 336-mile (540-kilometre) man-made canal. Using surface water for a new water supply required that White Tanks comply with the United States Environmental Protection Agency’s (USEPA) Long Term 2 Enhanced Surface Water Treatment Rule (LT2 Rule).

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Case study about the TrojanUVSwift installation at the White Tanks Regional Water Treatment Facility in Arizona that provides an additional barrier to Cryptosporidium

Disinfecting New York City’s Drinking Water

The Long Term Enhanced Surface Water Treatment Rule requires unfiltered surface water plants to install treatment to inactivate Cryptosporidium. Engineers working on New York City’s Catskill/Delaware project evaluated a new filtration plant, but the cost of installing a two-billion-gallon-per-day filtration facility was significantly greater than other alternatives. After evaluation of available technologies, it was decided that UV was the most practical and cost-effective solution.

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 Case study about the world’s largest UV drinking water installation that disinfects New York City’s drinking water

About Giardia

  • Giardia is a protozoan that is protected by an outer shell and is one of the most common waterborne parasites
  • Although Giardia is often referred to as a camping or backpacking-related disease (beaver fever), it can also be found in swimming pools, hot tubs, and contaminated drinking water
  • It causes the diarrheal illness known as giardiasis – signs and symptoms from a Giardia infection can last two to six weeks

Traditional methods of chlorine-based disinfection require high concentrations and contact times to eliminate Giardia, a situation that is further exacerbated by cold water conditions and leads to increased disinfection by-product formation.

UV Disinfection as a Giardia Barrier

Where the design of chlorine-based disinfection systems is governed by highly chlorine resistant organisms like Giardia, UV disinfection offers a very cost effective treatment solution to reduce the chlorine CT (contact time). In this type of application, UV can form part of a disinfection by-product reduction strategy. Furthermore, a UV disinfection system’s small footprint can also provide significant cost and space savings compared to the design and construction of a chlorine contact chamber expansion.

UV in Action

Disinfecting Drinking Water in Amman, Jordan

The King Abdullah Canal is the primary source of drinking water for Amman. It receives its water from Lake Tiberias (also known as the Sea of Galilea) and the Yarmouk River. The Zai Water Treatment Plant, which takes raw water from the canal, was required by the Ministry to install UV treatment to treat Cryptosporidium and Giardia.

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Case study about the TrojanUV installations at drinking water treatment plants in Jordan providing an additional barrier to Cryptosporidium and Giardia

Systems for Cryptosporidium & Giardia Barrier

TrojanUVFlex 100 Series chamber


The TrojanUVFlex® is designed with features to make installation and operation simpler, faster and more cost-effective than ever before. Built on the proven TrojanUV Solo Lamp® Technology platform, TrojanUVFlex allows for energy-efficient high-intensity delivery of UV light in an extremely compact footprint.

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The TrojanUVSwift® is a testament to our commitment to providing water confidence. It boasts comprehensive validation at a wide range of flow rates and UV transmittance levels in full compliance with the protocols of the United States Environmental Protection Agency UV Disinfection Guidance Manual.

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TrojanUVSwiftSC chamber


The TrojanUVSwift®SC is designed to treat flow rates of 20 gallons per minute (GPM) to 16 million gallons per day (MGD) or 4.5 to 2,525 m3/hr. These compact UV systems offer small communities an economical solution for drinking water disinfection. 

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