June 2001
Volume 43 Number 6
 

UV: Walkerton Case Study -- Shedding New Light on Water Treatment
by Lyn Ibson   Pages: 

Summary: In May 2000, an E. coli outbreak caused seven deaths and drew a dark cloud over water quality issues on a small town in Ontario, Canada. With time a precious commodity at the outset, urgent action was a necessity. As authorities worked to purge and restore the town water supply, residents began to explore a little-known (at least to that point) disinfection alternative in the form of UV. The chain of events is detailed below.

After the cold and damp of winter in southern Ontario, Canada, the long Victoria Day weekend in May is celebrated with a sense of eager anticipation for the coming summer. Bernie Reed and his family were in a mellow after-dinner mood on last year's holiday Monday as the news came on TV. The Reeds were shocked to hear the county medical officer had issued a "boil water" advisory for their hometown of Walkerton. Children and seniors throughout the town were seriously ill. An outbreak of E. coli bacteria was believed to be the cause. The town water was no longer safe.

Bernie knows more about water than the average TV viewer. He and his partner, Doug Schaab, own the largest plumbing and heating dealership in the Walkerton area. He routinely sold water disinfection systems to his rural customers. But he, like everyone else in town, had an unquestioning faith in the town water. Bernie was confident whatever problem led to the medical officer's order would be contained quickly. It would be inconvenient but "nothing huge," he thought.

He was wrong.

Walkerton gets on the map
The town of Walkerton, located 120 miles west of Toronto, Ontario, has a population of about 5,000 people. A series of wells supply water to the municipal utility that, like most towns in the area, relies on filtration and chlorine disinfection for treatment. While UV technology is commonly used for both municipal and point-of-use (POU) disinfection in other parts of the world, few people in Walkerton had ever heard of it.

But, over ensuing weeks, Walkerton's water would make news all over the world. This was the largest E. coli outbreak in North American history. Fully half the population of Walkerton would be stricken with illness from the tainted water. Many were hospitalized. Several died. Schools closed. Even at church, parishioners became fearful of shaking hands and risking disease. Six months would pass before Walkerton could turn taps on again.

The problem's magnitude began to reveal itself the day after the boil-water order was issued, when the Ontario Clean Water Agency (OCWA) phoned Bernie at work. OCWA, an agency that operates many larger water treatment plants in Ontario, was taking over the town's water supply and directing the effort to contain the outbreak. Bernie's business, Reed & Schaab ClimateCare, had the area's largest staff of plumbers and OCWA was drafting all the help it could get. As the agency explained what was involved, Bernie could see the effort would be "huge" indeed.

Plenty of questions
Shaken by the idea they couldn't rely on the safety of their water supply, residents quickly turned to a search for alternatives. Bernie Reed's staff was no different, but had greater responsibilities to their customers. The recurring question was, "How can we protect ourselves from E. coli?"

ClimateCare had been installing ultraviolet (UV) disinfection systems for over 10 years. But even Bernie couldn't tell customers with certainty that UV was effective against E. coli. As it happens, the head office of his supplier was located in nearby London, Ontario. Bernie's contact there was able to give him the assurances he needed -- at conventional design doses, UV is a proven defense against identified target waterborne pathogens, including bacteria, viruses and other protozoans. Ironically, Bernie learned his supplier was just preparing to launch a new series of UV systems developed specifically for point-of-entry (POE) disinfection. With variable capacities ranging up to 40 gallons per minute, the line would be ideal for residential and commercial installations in Walkerton.

But Bernie was already learning that, where drinking water is concerned, technology alone isn't enough.

Shutting down the water
For the moment, OCWA was more concerned with Walkerton's existing supply system than new UV technologies. First, over 2,000 homes would have to be disconnected from town water. Since plumbing inside each home was contaminated, cisterns commonly used in Walkerton homes would also be disconnected. The same work was needed for every business and institution. Then, every water pipe and fixture in town had to be flushed with a strong bleach. Alternate water supplies, mainly bottled water, were to be distributed. At the local hospital, seniors' homes and other designated facilities, new plumbing was needed to hook up with tanker trucks delivering clean water.

"It was like going to war," Bernie recalls. "Bunker time. The whole community had to jump in and do whatever they could."

ClimateCare became "command central" for the decontamination campaign. While Bernie's plumbers headed out in OCWA vans, his dispatcher, Elaine Lippert, stayed on the radio to deploy the growing legion of plumbers arriving from all over southern Ontario to help out. According to Bernie, "the plumbers worked from 7 a.m. to 10 p.m. for three weeks straight, but Elaine put in more hours than anyone. She held it all together and still dealt with all the calls and questions from our customers."

Formula for drinking water
Bernie was uncomfortable with the answer he had to give. UV could be the right solution for his customers, but not yet. Bernie's UV supplier learned long ago, as a leading developer of both wastewater treatment systems and drinking water systems, that novel technologies are an uphill sell. In short, "If it ain't broke, don't fix it."

In Walkerton, the system was broke, but few people knew where to look for effective alternatives. In Europe, where authorities prefer to avoid chemical treatments that can impact the environment, UV has been used in water disinfection for 90 years. It controls anything that has nucleic acids, including pathogens that cause staph and strep infections, Salmonella, hepatitis and, of course, the potentially deadly consequences of the strain E. coli 0157:H7. More recently, low doses of UV have proven to be equally effective against protozoan organisms, such as Giardia and Cryptosporidium, which are resistant to chlorine treatment.

Uncharted waters
But in most North American jurisdictions, water regulations pre-date UV. Industry representatives were in Walkerton to explain how POE UV could help the beleaguered town. But without proper guidelines encoded for UV in their standards, regulators couldn't take advantage of the technology when they needed it. They couldn't allow UV systems to be installed on Walkerton's water lines until the entire system was decontaminated and tested safe again -- a six-month process.

JoAnn Todd also received a crash course in UV as a result of the Walkerton crisis. JoAnn is managing director of Maple Court Villa, a 56-unit retirement residence. She heard rumors of a problem with the water on the Friday before the boil-water advisory came down. She even called the utility commission and was told the water was safe. Next, she advised the health unit that three residents were ill with nausea and diarrhea. "Many of our elderly residents have fragile immune systems," she explains. "More than half of our residents became ill, two of whom later died." When the boil advisory was issued, her kitchen staff had to throw out all the foods and juices they had prepared with the contaminated water, then start boiling water to replace the stocks. Notices to stop using the water were posted in residents rooms and bathrooms, and extra staff put on to deliver safe water to residents."

Before the week was out, JoAnn received a message from Rod Black, a representative from the same UV manufacturer that supplies Reed. His company was ready to donate a UV system, almost $10,000 worth of equipment to supply Maple Court with safe water. JoAnn, unfamiliar with UV, was skeptical at first, but after meeting with Rod and learning what UV could do, she was pleased and surprised by the gift. Just two weeks after the outbreak, Maple Court had its own water disinfection system. But again, authorities weren't prepared to permit use of any unfamiliar technology. In spite of the new system, JoAnn's kitchen staff was under orders to continue boiling water from May to December 2000.

Returning to 'peace of mind'
The UV system at Maple Court later proved to be a blessing. As JoAnn Todd says, "People still have questions about the water in Walkerton. With our UV system, residents and their families have an extra assurance that we have super-clean water. It gives them a sense of security, and our residence is now at full capacity."

Bernie reports that, in 2000, his UV system sales rose 10-fold over any other year. "Usually we just sell UV to farms drawing their own water. But this fall, people in town started buying. The more we learn about our water, the more we realize how difficult it is to keep the water safe; there are so many factors involved and not all of them are in our control. The aquifer we draw Walkerton's water from has never even been mapped -- contamination could come from anywhere! Most people trust that the problem is solved, but for some, the UV system provides some extra peace of mind."

In the wake of the Walkerton crisis, Ontario investigated water treatment practices at every municipality in the province. Nearly half were ordered to take some form of corrective action. Meanwhile, Bernie has seen a burgeoning range of new water treatment ideas offered to his business. He said, "Some of these are, you know, pretty dubious. But I just ask, 'Where's the scientific evidence?' At least with UV, when my supplier tells me what a system can do, they have the data to back up their claims."

Conclusion
Clearly, the middle of a crisis is no time to start experimenting with unknown ideas. But Walkerton's experience also shows the cost of failing to keep pace with emerging solutions. By continuing to ask, "Where's the scientific evidence?" -- the water industry, water authorities and homeowners will have earned their peace of mind when they need the answer down the road.

Acknowledgment
The company that provides UV equipment to ClimateCare is Trojan Technologies Inc., of London, Ontario, Canada. Its new line of POE UV systems is known as the TrojanUVMax. Bruce Laing is ClimateCare's contact at Trojan.

References
1. Cairns, W., and H. Wright, "UV Disinfection for Drinking Water: Candidate for Best Available Technology," Trojan Technologies Inc., London, Ontario, Canada.
2. Carrington, E.G., et al., "Disinfection of Potable Water by Ultraviolet Irradiation-A Critical Review," Water Research Centre, United Kingdom, 1989.
3. Clancy, J.L., et al., "Using UV to Inactivate Cryptosporidium," Journal AWWA, Vol.92, Issue 9, September 2000.
4. Sakamoto, G., "UV Disinfection for Cryptosporidium and Giardia in Drinking Water," Trojan Technologies Inc., London, Ontario, Canada.
5. Shin, G-A, et al., "Low Pressure UV Inactivation of Cryptosporidium parvum and Giardia lamblia based on infectivity assays and DNA repair of UV-irradiated Cryptosporidium parvum oocysts," AWWA Water Quality Technology Conference proceedings, November 2000.
6. Lorch, W., and G.O. Schenk, "Ultraviolet Sterilization," Chapter 16, Handbook of Water Quality Purification, 2nd Edition, 1987.
7. Wright, H.B., and G. Sakamoto, "UV Dose Required to Achieve Incremental Log Inactivation of Bacteria, Virus and Protozoa," Trojan Technologies Inc., London, Ontario, Canada, May 2000.

About the author
Lyn Ibson is a freelance writer based in London, Ontario, Canada.