Water treatment program

Ultraviolet light disinfection

A multi-barrier approach is the best protection for Winnipeg's water. Ultraviolet light (UV) disinfection has been operating and protecting Winnipeg residents against waterborne parasites since May 2006. It was the first treatment process of our new water treatment program.

Why are we using UV disinfection?

We disinfect our water with chlorine to protect against harmful viruses and bacteria, such as E. Coli. However, chlorine is not effective against waterborne parasites such as Cryptosporidium (Crypto). These parasites can cause illness and can be life-threatening to some people. Crypto has been found in almost all surface waters in Canada and the United States. We routinely test our water and samples from Shoal Lake and Deacon Reservoir are normally negative for Crypto. While the risk of a waterborne disease outbreak is low, UV virtually eliminates this risk.

What is UV disinfection?

Photo of the water treatment program's ultraviolet light chamber

One of six stainless steel UV disinfection chambers

UV is nature's own disinfection method. UV light rays are found in natural sunlight. Ultraviolet light disinfection involves exposing water to UV light rays. The UV light rays penetrate micro-organisms and destroy their ability to reproduce. They are no longer able to cause infection and illness and are therefore harmless. UV light, at the doses used in our facility, effectively protects against parasites, such as Cryptosporidium and Giardia.

How does UV disinfection work?

Water flows through six stainless steel chambers. Inside each chamber are nine lamps, similar to fluorescent bulbs. Each lamp is housed in a transparent, waterproof quartz sleeve. The sleeves are submerged in the chambers. As the water flows through the chambers, the micro-organisms are exposed to the UV light rays. There is one sensor outside each sleeve to ensure that an adequate UV light intensity is applied.

How long is the water exposed to the UV light?

The water needs only a few seconds of exposure to the light to inactivate micro-organisms.

Overview of UV chambers installed inside Deacon Reservior pumping station

UV chambers installed inside
Deacon Reservoir pumping station

Where was UV disinfection installed?

The UV disinfection chambers were installed in the existing Deacon Reservoir pumping station. This innovative approach saved $34 million, when compared to the cost of early construction of a stand alone UV disinfection facility.

How much did it cost to install the UV system?

The cost to install UV disinfection was about $9 million.

What are the advantages of UV disinfection?

Ultraviolet light disinfection:

is very safe – there are no dangerous chemicals to handle, store, or monitor
has no danger of overdosing or over-treating
is environmentally friendly – other than disposing of used lamps, there is little or no impact on the environment
causes no change to the taste, odour, pH, or the general chemistry of the water
requires very little contact time as the disinfection process is immediate – there is no need for holding tanks
has few moving parts to wear out

Other interesting facts:

Internal view of UV disinfection chamber

Stainless steel chambers (6) Weight of each chamber Length of each chamber Diameter of each chamber	2,700 kg (6,000 lbs) 3.95 metres (13 feet) 1.22 metres (4 feet)
Lamps (54) Cost of each lamp Guaranteed life Lamp power rating	$940.00 5,000 hours 20 kW
Sleeves (54) Guaranteed life Cost of each sleeve	10 years $800.00
Sensors (54) Cost of each sensor	$1,600

Last updated: June 29, 2018

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