Backflow Incident Details
This page provides the details of backflow incidents that have occurred locally and across the country. Incidents are listed with the most recent first.
Backflow Incidents in Greater Victoria
June 1989 - Victoria, BC - Machine Coolant from Manufacturing Plant
On June 12, 1989, the City of Victoria Water Department shut down a block of water main for repair work. All businesses on the block were advised that the shutdown would take place from 11:00 p.m. to 2:00 a.m. the following day. The next day, an employee of a manufacturing company on the block took a drink of water from a fountain and immediately vomited. The water was a dark green color and had a bitter taste.
A cross connection inspection revealed a tap with a hose leading into a tank containing a mixture of water and machine coolant. Tests of the drinking water indicated that the water contained a high level of copper and (likely) the coolant. It was assumed the tap was open during the period the water was shutoff, resulting in the backsiphonage of the contaminant into the potable water system. The pink color coolant, after sitting in the plumbing system for several hours, had reacted with the copper piping, causing the water to turn a dark green color.
Nov 1988 - Victoria, BC - Saltwater from Navy Dockyards
On Sunday, November 6, 1988, a naval ship tied up to a jetty in the government dockyard and connected its fire protection system to a fire hydrant. This connection to the fire hydrant would not have occurred under normal conditions. The ship had six fire pumps on board, but three of the pumps were malfunctioning at the time. When the fourth pump stopped operating, the ship's officers became concerned, and connected the ship's fire protection system to the dockside fire hydrant to augment their system.
It was assumed that the dockside fire protection system was a saltwater system. Unfortunately, it was a combined domestic and fire protection system. When the pressure in the ship's system increased after connection to the fire hydrant, it was believed that the pressure from the dockside system would stay high. In fact, the connection was made late at night when the domestic supply pressure was at its highest. With the increased demand on the system during the day, the supply pressure dropped. The higher pressure in the ship's (saltwater) fire protection system forced the non-potable sea water into the dockyard's domestic water system.
Tests using silver nitrate indicated that the contamination was quite extensive, almost to the dockyard service connection to the municipal water system. Backflow protection assemblies were not present on either the dockside hydrants or the service connections to the municipal water system.
To remove the saltwater and the accompanying bacterial contaminants, the dockyard water system was flushed and a chlorination system, borrowed from a swimming pool, was installed to inject 6 ppm chlorine to disinfect the system. The chlorination continued until November 12th.
March 1986 - Victoria, BC - Corrosion Inhibitor from Air Conditioner
In March, 1986 the City of Victoria Water Department received a complaint from the Provincial Museum that their water "Smelled of ether". The odor was a reoccurring problem, with its strongest level being noticed in the early morning.
The inspection of the museum confirmed the odor. By following the water system to the area of the strongest odor, it was concluded that the source was the museum's air conditioning/humidifier unit installed in the basement. The make-up water tank for this unit contained a corrosion inhibitor that smelled like ether. The unit's pump operated at a higher pressure than the city water pressure.
A reduced pressure principle backflow prevention device was ordered installed on the water connection to the air conditioner/humidifier unit and the water system ordered flushed.
Backflow Incidents in British Columbia
Jan 1993 - Vancouver, BC - Blue Sanitizer from Toilet.
In January, 1993 the Vancouver Health Department received a complaint from a customer that his hot water was coming out blue and soapy. On investigation, it was noted that light blue water flowed from the hot water side, while the cold water appeared clear.
On questioning the complainant and reviewing the building water system, it was determined that the rear outside tap had frozen and sprung a leak during a recent cold spell. The owner had shut off the main water supply valve and had cut and capped the water line leading to the outside tap. It was during this event that the complainant noted blue water for the first time.
On further investigation it was noted that the toilet in the attic bedroom had blue toilet sanitizer in the tank and bowl. The attic washroom had not been used for a long period of time and the owner had forgotten about the sanitizer.
It was concluded that some of the toilet tank water containing colored sanitizer was drawn into the building's water distribution system during the water line break and repair event. A considerable amount of cold water had been run after the event, which flushed the cold water side clear prior to inspection.
Nov 1987 - Burnaby, BC - Auxiliary Water From Temporary System
On November 2, 1987 a break occurred on the municipal water main supplying water to a paperboard plant and other nearby industrial properties in Burnaby, British Columbia. During the repair work, apparently polluted (dirty) water discharged from the broken main into the excavation although the isolating valves on the main were shut off.
Upon investigation, it was determined that the backflow of water was from a paperboard plant located along the Fraser River. The plant's only source of potable water, the municipal water main, was disrupted during the main repair, hence the continuous backflow of water through the plant's service connection must be from an auxiliary source of supply. The plant's service connection did not contain a backflow prevention assembly for premise isolation.
The plant maintained two water systems; a combined fire, industrial and domestic system supplied from the municipal water main, and a process system supplied from pumping water from the river. To keep the plant in operation after the water main break, a fire hose was connected between the two systems. The river water was pumped into the plant's domestic water system as well as the isolated portion of the municipal system.
The municipal work crew ordered the fire hose cross connection removed. The crew flushed and disinfected the municipal water main. The plant was ordered to immediately flush and disinfect their domestic water system and immediately install a reduced pressure backflow prevention assembly on their water service connection to provide premise isolation.
Dec 1986 - Vancouver, BC - Green Water from Commercial Buildings
At 2:30 a.m. on December 11, 1986, the Greater Vancouver Regional District's 96-inch underwater crossing of Burrard Inlet ruptured. This transmission line is one of three transmission lines supplying the City of Vancouver from mountain reservoirs; two underwater crossings and one overland transmission main. At this time, the overland transmission line supplying the Vancouver region was out of service for reconstruction of a dam intake structure. The flow of water from the ruptured pipeline was 420 mgd, with approximately 100 mgd from the Vancouver side. The high flows through the one remaining transmission route resulted in low or negative water pressure (vacuum) throughout much of Vancouver's distribution system for a three hour period. The area affected included the Downtown Business District, adjoining West End highrise apartment area, and the west side residential districts. Approximately 140,000 of Vancouver's 430,000 population were without water or supplied downstream from a distribution system subjected to negative pressure (vacuum) that could permit backsiphonage of contaminants into the water supply.
The number of water quality complaints were too numerous to record. The high flows through the transmission and distribution system resulted in the water becoming dark brown in color from the disturbed iron oxide laden sediment in the predominantly cast iron distribution system. Due to the lack of staff during the emergency, individual water quality complaints could not be investigated. Typical of the complaints indicating a possible backflow incident was the "green water" complaint from commercial buildings.
Bacteriological samples collected in the late morning of December 11, following the restoration of the water pressure showed 12 out of 15 samples from areas with low or negative pressure had positive total coliform counts; two of the 12 positive samples also had positive fecal coliform counts. The source of the bacteria could have been either backsiphonage through leaks in distribution mains or through cross connection from within the distribution system or private plumbing systems.
Mar 1978 - Vancover, BC - Corrosion Inhibitor from Boiler System.
On March 10, 1978 the residents of a high rise apartment building in Vancouver's West End reported that their water had a blue color and a bitter "rubbery" taste. Water Department staff responding to the complaint determined that the "blue" water was confined to the apartment building.
An inspection of the apartment revealed that the single soft seated check valve on the boiler feed line was leaking. The expansion of the water (steam) when heated caused a backflow of the water in the boiler past the leaking single check valve into the domestic water system. The analysis of the tap water revealed that the water contained a corrosion inhibitor, Bramco 750, that was presently being used in the apartment's boiler for the hot water heating system. Only one of the three components of Bramco 750 is toxic when used full strength. With the dilution of the corrosion inhibitor after mixing with the potable water, the consumption of it would not be toxic.
The Water Department issued an order to replace the single check valve with an approved reduced pressure principle backflow prevention device. The apartment's domestic water system was thoroughly flushed to remove all traces of the corrosion inhibitor.
Jan 1978 - Vancouver, BC - Carbon Dioxide from Beverage Machine
On January 18, 1978 employees of a theater reported that the water in the building had a blue color and a strong "mineral" taste. The problem occurred intermittently and a sample of the water taken that afternoon revealed nothing unusual. However, a sample taken and analyzed the next day was found to contain 245 parts per million of copper. Drinking water standards suggest a limit of 1.0 ppm of copper.
A cross connection inspection found a pressure regulator on a carbon dioxide cylinder used at the beverage bar had malfunctioned, resulting in a large amount of gas entering the domestic water system. The standard ball check valve installed on this type of beverage dispenser was ineffective in preventing backflow.
The carbon dioxide formed carbonic acid, which caused rapid internal corrosion of the copper water piping in the theater.
Although copper is not considered to be a cumulative systematic poison such as lead or mercury, a high concentration in the water supply may cause nausea or discomfort, and in a very limited number of people, an allergic reaction.
1972 - New Westminister, BC - Auxiliary Water from Dual Water System
A large mill on the Fraser River near New Westminster, British Columbia began experiencing a high rate of absenteeism. The Personnel Manager called on the local health unit to see what might be the cause. The absent employees showed the following symptoms:
1. Stomach Cramps - moderate to severe
2. Diarrhoea - severe, lasting up to six weeks
3. Considerable weight loss (7-20 lbs.)
However, appetites were generally good and employee's families were not affected.
Inspection of the premises revealed that the cafeteria and food dispensing devices were kept clean and sanitary, as were water fountains and washrooms. However, a dual water system was noted. One was connected to the City water supply and provided for washrooms, drinking fountains, automatic food machines and the domestic system generally, as well as for fire hydrants, sprinklers, boilers and various other mill operations. The other was an auxiliary system, connected to that section serving the mill operation. Water for the auxiliary system was drawn from the Fraser River by a pump which was activated whenever the City supply dropped below a set pressure. Also, it was noted that the river inlet was close to the City sewer outfall. There was a check valve below the domestic section and the industrial portion. However, further checking of the system showed that whenever the automatic pump drew water from the river, it was forcing the water past the check valve on the domestic side of the system. No lives were lost but the episode was certainly expensive in terms of days off work and lost production.
Backflow Incidents in Canada
Apr 1992 - Winnipeg, MA - Blue Disinfectant Water from Toilet Tanks
It began in April, 1992 when a tenant of a Seniors Residence complained of periodic "blue colored" water coming from her taps. Laboratory Services collected cold water samples but no blue coloration was evident and test results were inconclusive.
In July, 1992 the tenant returned from abroad and complains of "blue" water again. Tenant advises that the blue water condition is intermittent and usually occurs in the bathroom but has occurred in the kitchen sink. According to the Chief Maintenance person, this is the only tenant in the complex that has experienced the blue water problem.
The Backflow Prevention Branch of City Health conducted an investigation and inspection to determine the cause of the blue water. Plumbing system and heating/cooling system were checked. Suites along the vertical riser plumbing system were checked for possible backflow/cross connection situations, as well as the main floor businesses (hair dresser, bakery/restaurant). Water samples were collected from various locations for analysis. Tenants in three suites above the vertical riser were found to be using blue toilet bowl disinfectant cleaners in their toilet tanks. Because of the plumbing deficiencies, blue disinfectant water could possible backflow into the water system under the right conditions. Plumbing deficiencies were corrected immediately.
1992 - Edmonton, AB - Sudsy Water from Pump in Plastics Factory.
Edmonton's water department received a call from a plastics manufacturing plant complaining of sudsy water in their hot and cold water lines. Investigation of the facility found that all the equipment, and individual outlets had the appropriate backflow prevention devices except one hose bib. A hose was connected to this outlet and attached to the process water pump so that it could be primed. Apparently, a hose connection vacuum breaker had been installed when the building was under construction. However, the operators found it a nuisance, as every time the pump was turned the hose connection vacuum breaker started to spray water from the relief ports. It seemed reasonable to simply take the hose connection vacuum breaker off and connect the priming hose directly to the hose bib. This certainly solved the spillage problem but it also created an unseen hazard. The pressure the pump produced overcame the city water pressure and forced the process water, which contained potassium hydroxide and calsolene oil, back into the domestic cold water supply.
Employees at the site had been drinking water the day of the contamination. They complained of raw throats. Fortunately, not enough of the substance had been consumed to cause any serious health effects.
A reduced pressure principle backflow preventer, to the process area, was installed along with a proper backflow preventer to the process water line used to prime the pump.
Jun 1991 - Edmonton, AB - Super Chlorinated Water from New Main
In June, 1991 a water quality complaint was received from a local college. When the water quality inspector arrived, he noticed a strong chlorine odor coming from the lawn where a hose had been left running. Two of the water department's troublemen had already isolated the area and had taken samples from fire hydrants on the main water distribution system. These samples were within normal parameters, indicating that it was an internal problem. Water samples taken inside the complex showed chlorine levels higher that what the test equipment could measure.
Upon investigation it was found that the mechanical contractor had installed a new eight inch water line to supply the existing building as well as a new addition. The old service was to be abandoned. The new line was super chlorinated to disinfect it; then drained using a garden hose connected to a cap at the end of the line. According to the contractor's foreman, water samples were taken to a lab for testing. Apparently, the samples were approved. However, it was not substantiated that these samples were ever taken. Thereafter, a fire hose was connected from the new system to the existing water line. The old system was then turned off at the water meter and the new system turned on. The chlorine in the new water line had not been properly flushed, resulting in a tremendously high concentration of chlorine.
The contractor and staff were instructed to flush every faucet and outlet in the building. By 6:00 a.m. the next morning, a sample taken to the water treatment lab showed chlorine concentrations were down to normal, 0.04 mg/L. Twenty seven other chlorimeter tests on the hot and cold water system, throughout the complex revealed that the chlorine levels were within acceptable ranges.
Apr 1991 - Edmonton, AB - Rusty Water from Fire System
In April of 1991 an LRT station experienced problems with the water in the staff washrooms and in the janitor's room. Inspection of the facility found that the fire system header was separated from the domestic water system by a single check valve. Examination of the check valve found that rust build up kept it 3/4 inch ajar.
Water samples taken to an independent laboratory had the following results: Fe (mg/L) 0.99, Pb (mg/L) 0.39, P (mg/L) 697.9.
Water samples taken from the buildings on either side of the station were normal. A DCVA was recommended to be installed in the water line supplying the fire system
Oct 1989 - Edmonton, AB - Smell from Fermenting Vessel
On October 25, 1989 the laboratory and offices of a research facility were shut down after a growth nutrient for micro-organisms backflowed into a hot water system.A soupy, non-toxic fluid used as a growth nutrient was being injected into a fermenting vessel. Hot water, used for dilution, was provided by a direct cross-connection to the fermenting vessel. Because the injecting pressure was "too high", up to 150 litres of the growth nutrient backflowed into the domestic hot water system. The backflow incident was detected when staff noticed a smell coming from the hot water taps in the building.
Although the growth nutrient was not considered a health risk, contamination of the potable water supply could encourage the growth of any small amount of bacteria in the water supply.
The cold and hot water lines in the building were chlorinated and flushed.
Oct 1989 - Edmonton, AB - Contaminants from Fire Hose Cabinets
In October of 1989 the Edmonton Board of Health and the Cross Connection Control Office were called to investigate a complaint of contaminated water supplying a drinking fountain. The inspectors found that black iron pipe had been piped to supply fire hose cabinets as well as a drinking fountain and a sink.
The building where the drinking fountain and sink were located was used sparingly, causing a build up of contaminants. Plant officials were requested to re-pipe the domestic water and fixtures with potable water carrying material to a point upstream of the black iron pipe. A DCVA was also requested on the line supplying the fire hose cabinets.
Aug 1989 - Edmonton, AB - Brown Water from Fire Pump System.
In August of 1989 a printing shop owner complained of brown water in the washrooms and in the equipment. The owner mentioned that the contamination appeared each time the tire warehouse next door tested their fire pump.
The inspector found that the newly installed fire system was separated from the potable water by a ULC wafer check valve. The owner was instructed to install a D.C.V.A. in the water line to the fire system. After the D.C.V.A. was installed, no further complaints were recorded.
July 1989 - Edmonton, AB - Glycol from Fire System
In July of 1989 a call from one of Edmonton's light rail transit stations indicated that a yellowish, oily water was observed in the public washrooms.
It was learned that a maintenance crew had used a fire hose to flush out a sewer line shortly before the incident occurred. The line to the fire hose was separated by a 4-inch ULC approved wafer check valve on the fire pipe stand and 2 8-inch ULC approved wafer check valves on the header of the sprinkler system. All three valves on inspection were found to have deposits which prevented the valves from closing tight.
The inspector recommended a R.P. be installed in the water line supplying the system as glycol was used in the stand pipe.
May 1989 - Edmonton, AB - Brown Water from Fire System.
In May, 1989 occupants of a department store in one of Edmonton's shopping malls complained of brown water coming out of the faucets throughout the store.
The Cross Connection Control Inspector found that the alarm check valve, in the fire system, had gone off on several occasions when the City water pressure had been disrupted.
Water samples indicated turbidity and iron content higher than acceptable drinking water standards. Water samples from neighboring stores were normal.
The owner of the building was asked to install a D.C.V.A. in the water line supplying the fire system.
Jan 1989 - Edmonton, AB - Green Dye from Pumped Holding Tank
Workers at a plastic manufacturing plant were astonished to see green water flowing from the cafeteria water taps. They immediately notified the water department of the problem.
The investigator found that a bypass valve connected to the downstream side of a pump was inadvertently left open. This pump took recycled water from a holding tank to cool various equipment throughout the plant. Since the pump created a higher pressure than the City water supply it forced the water from the holding tank back into the potable water system. Fortunately, the green dye from the plastic manufacturing process alerted the employees of a problem before anyone drank the water.
Water lines were flushed and a reduced pressure principle backflow preventer, which was not bypassed, was installed in the line to the pump. Numerous other backflow preventers were also installed after a complete inspection of the facility was conducted.
Sept 1988 - Edmonton, AB - Contaminants from Fire System
In September, 1988 occupants of a high rise office building in Edmonton, Alberta complained of brown water flowing from the faucets throughout the building.
The Cross Connection Control Inspector found the domestic water pump had been taken out of service for repairs. The piping between the fire system and the domestic water supply was arranged in such a way that it allowed either pump to serve both systems when a bypass valve was turned on. A single wafer check valve failed to contain the contaminants in the fire system; as a result, the fire system contaminated the domestic water supply.
The inspector recommended that the system be separated and a double check valve assembly be installed in water lines serving the fire systems and the high rise's domestic cold water supply.
Aug 1988 - Edmonton, AB - Murky Water from Heating System
Patrons & staff in one of the larger stores in a shopping center noticed that water in the cafeteria and washrooms was murky. Investigations by the inspector found that a water line in the vicinity had broken disrupting the water supply to parts of the shopping mall. An inspection of the water system within the building found that a single hard seated check valve had failed allowing water from the heating and chilled water system to enter the potable water system.
The owners were instructed not to use the water until all the lines were properly flushed and water samples confirmed the water was safe to drink. In addition, a reduced pressure principle backflow preventer was installed in the water line serving the heating and cooling system.
Apr 1988 - Edmonton, AB - Blue Water from Toilet Tank
A home owner called the Cross Connection Control Office wondering why he had blue water coming out of his taps. The inspector sent to investigate found that there had been a water mainbreak in the area where the complaint was registered. An inspection of the residence found the toilet tank had a cleaning dispenser in it and the ballcock was below the water level. When the water in the street was turned off to repair the leak a vacuum was created. The ballcock did not have an anti syphon feature and allowed the water from the tank to be syphoned back into the water system. When the water was turned back on the blue color from the toilet bowl cleanser alerted the owner of the problem. An anti-syphon ballcock was installed so that its critical level was 25mm above the overflow tube solved any future contamination problems from this toilet tank.
Dec 1987 - Calgary, AB - Chromates from Hot Water Heating System
On December 11, 1987 the City of Calgary experienced a water main break that interrupted the water supply to an elementary school.
During the water main break a backflow condition occurred and backpressure from a hot water heating system forced chemically treated water into the school's potable water service supply. When the water main was repaired and the water pressure restored, the chemically treated water was forced into the school's distribution system, supplying contaminated water to drinking fountains and washrooms. These contaminants showed up in water samples routinely taken after a water main break. The laboratory identified these contaminants as chromates, a very highly toxic chemical compound.
Fortunately, the children were sent home at the time of the water main break and did not drink any of the contaminated water. The school remained closed for several days while the school's water distribution system was flushed, sampled and re-flushed until water samples revealed no chemical traces. Backflow protection was requested by the inspector, and was installed on the water supply to the heating system.
Aug 1987 - Edmonton, AB - Carbon Dioxide from Drink Dispenser
In August, 1987 the staff at one of Edmonton's recreational parks called the water department complaining that one of their customers had taken a drink from a drinking fountain and complained of caustic tasting water which caused a burning sensation in his throat. The inspector, dispatched to the site, noticed blue stains in some of the concession stand equipment and air in the water lines. Further investigation found that the soft drink carbonator dual check valve had failed allowing the carbon dioxide to enter the water system.
Water lines in the facility were flushed and a stainless steel dual check valve with atmospheric port was installed to replace the faulty device.
Jun 1987 - Kitchener, ON - Nickel Solution from Plating Rinse Tank.
On June 14, 1987 the employees of an electroplating plant in Kitchener, Ontario noticed the water from one of the plant's drinking fountains "looked like Kool-Aid" and had a metallic taste. Because of the heat in the plant the employees were drinking a lot of water. By Friday, June 19, twenty-nine workers had reported being exposed to nickel contamination. Eleven were in the hospital, and six others were under observation by their family doctor for symptoms of nickel poisoning. Ingested nickel could harm the lungs, kidneys, liver and immune system.
The nickel solution most likely entered the plant's water system by backsiphonage through a submerged inlet (cross connection) to a plating rinse tank. On Sunday afternoon, the water system was shut down for repair work. The submerged connection was not protected by a backflow prevention assembly.
Mar 1987 - Edmonton, AB - Hot Water from Boiler System
In March, 1987 a maintenance company's service man contacted the department expressing concern over hot water coming out of cold water taps in certain areas of the high rise apartment he was servicing. An investigation of the water system traced the problem back to a faulty single hard seated check valve in the water line supplying the boilers. Apparently, the previous maintenance contractor had trouble keeping chemicals in the heating system, but instead of determining the cause, they simply added more chemicals.
There were no reported cases of anyone becoming ill. However, since the chemicals had been injected into the drinking water system for quite some time, one wonders how those chemicals affected the long term health of the tenants.
The single check valve was replaced with a reduced pressure principle backflow prevention device.
July 1986 - Winnipeg, MA - Anti-freeze from Boilers
On July 4, 1986 the City of Winnipeg Backflow office was asked to investigate a cross connection at a high rise apartment block. It was discovered that a check valve protecting three heating boilers had failed. The high pressure cold water pump was found to be fluctuating and when the pressure had dropped, anti-freeze from the boilers transferred to the potable water system
July 1984 - Edmonton, AB - Polypropylene Glycol from Heating System.
During the summer of 1984, personnel at a LRT station in Edmonton, Alberta complained about smelly, grey and bad tasting water. Some people developed stomach problems. When the Edmonton Water and Sanitation Department was alerted about the situation, water samples were Taken. The lab results showed a presence of polypropylene glycol in the water.
The investigation of the system showed that the three check valves installed on the system were all leaking. The installation of the proper backflow prevention device (double check valve) cleared up the problem.
1976 - Winnipeg, MA - Fertilizer from Nursery.
In 1976, in Winnipeg, Manitoba, as a result of snow clearing operations, two fire hydrants within a one block area were knocked over. The result was that through backsiphonage a blue colored liquid fertilizer from a nearby florist operation entered the water supply. Numerous consumer complaints were received. Since the contamination was colored, luckily no one ingested the water.
Apr 1973 - Toronto, ON - Cleaning Solvent from Automotive Undercoat Shop
On October 25, 1973, a backflow incident was reported in an automobile coating shop located in an industrial mall. Cars are driven into the shop for the application of undercoating and preventative coating in trunks, under hoods, door panels, etc., to prevent corrosion. The mall was only partially filled with tenants; the undercoating shop located in number 11, and the next occupied unit being number 21, leaving 9 unoccupied units in between.
In the pre-cleaning operation, hot and cold water was fed to pump operating at approximately 75 psi. The discharge side of the pump connected to a gun type spray nozzle. A hose was then connected from the pump into a solvent tank that supplied the solvent to the spray gun.
On October 25, the pump was left on between cycles, allowing the pump pressure of 75 psi to overcome the city water main pressure of 50 psi, causing the cleaning solvent to backflow into the potable water supply piping in the mall. A tenant in unit number 21, the next occupied unit, reported a bad taste in the water, leading to a discovery of the cross connection.
In order to clean the water piping of the contaminant, it was necessary to drain the lines, after which they were steam cleaned.
Backflow Incidents in USA
Missoula, - Potential Sewage from Improperly Connected Lines.
A boil order and health advisory remain in effect for Mountain Water Co. customers south of the Clark Fork River.
Health and water company officials will not know until 9 p.m. Wednesday whether sewage from an improperly connected line has contaminated Missoula's public water system. In the meantime, all Mountain Water customers who live in the area west of Eaton Street, north of Mount Street, south of Third Street and east of Patty Ann Drive should boil their drinking water.
And anyone who lives south of the Clark Fork River and has an immune system deficiency should take the same precaution - just in case contamination reached the larger water supply.
About 300 Mountain Water customers - homes and businesses - are within the area affected by the mandatory boil order. About 10,000 customers are affected by the health advisory.
To be safe, water must be boiled vigorously for a full minute.
Arvid "Butch" Hiller, vice president and general manager of Mountain Water, initially expected to have test results back Tuesday night, then learned that "the technical nature of this water sample and lab test requires a full 48 hours before it can confirm that there is no contamination."
The test will show whether coliform bacteria reached the public water supply - and, if so, whether the contamination included e. coli bacteria or fecal coliform.
"The likelihood of any contamination in our greater system is very small," Hiller said Tuesday night. "This area is very isolated from much of the rest of our system.
"Because of the hydraulics, it couldn't have happened in a better place. In this situation, where it happened, it is easily isolated."
Hiller said Mountain Water has flushed its entire system south of the Clark Fork, and elevated the amount of residual chlorine - disinfectant - in the water.
Lines leading to the three businesses most directly affected by the misplaced sewage line have been flushed and treated with a higher concentration of chlorine.
Hiller emphasized that Mountain Water was not responsible for the contamination - caused when a residential sewer line was accidentally connected to a water line serving three Reserve Street businesses.
It is now, however, Mountain Water's responsibility to notify its customers of the problem and sanitize the public water supply.
Working with the Missoula City-County Health Department, the water company released this list of dos and don'ts for customers south of the river:
Water in the larger health advisory area should be safe to drink. The source of contamination was disconnected, and Mountain Water flushed the lines.
The health advisory is directed at those people who have medical conditions that require them to be more careful than others, particularly people with immune system disorders.
In the smaller area affected by the boil order, water should be brought to a full rolling boil for one minute. Coffee makers do not heat the water to a rolling boil. So in the boil area, residents should use bottled water or boil their water before using it to make coffee.
Restaurants outside the boil order area do not need to take extra precautions with their water at this time.
Restaurants inside the boil order area must either boil their water or use bottled water. Bottled or boiled water should be used for cooking, drinking and hand washing. For dishwashing, use bleach in the final rinse, checking to make sure there is a residual of 50 parts per million.
If you drank the water all weekend, you do not need to go to the doctor. Simply monitor yourself and your family for symptoms associated with sewage-contaminated water. Those include diarrhea, cramps, nausea and possibly jaundice.
Remember that diarrhea can be caused by a number of things, and often resolves itself without medical attention.
Late Tuesday, Hiller said there "have been no credible claims of any illness at this point." "There really is such a small chance that there was any contamination in the larger system," he said. "The odds are very remote."
Hiller said the state Department of Environmental Quality will notify Mountain Water of the test results at about 9 p.m. Wednesday. If they show no contamination of the water supply, the boil order and health advisory will be lifted.
Backflow Incidents Worldwide
Aug 2004 - Sidney, Aust - Recycled Water from Unauthorized Plumbing Work.
Sydney Water is working closely with residents of the Rouse Hill area following discovery yesterday of a cross-connection of the recycled water and drinking water supply which affected around 82 households.
The cross-connection was the result of unauthorised plumbing work undertaken in the construction of a household in Rothwell Court, Glenwood. This in turn affected 82 households in Rothwell Court, Consolo Avenue, Carolyn Court and Rory Court.
Sydney Water identified the cross-connection late yesterday afternoon following a call from a customer and a subsequent inspection of the property by a Water Quality Scientist from Sydney Water.
According to Sydney Water Managing Director, David Evans, Sydney Water will undertake a thorough investigation to understand how such a breach of established requirements for this type of plumbing work occurred.
“We’re extremely disappointed that this incident – which was easily avoidable - has occurred.
“We will be vigourously investigating the matter including contacting the relevant licencing authority to pursue the reasons for the sub-standard work,” he said.
Mr Evans said once Sydney Water identified the cross-connection, the organisation immediately activated protocols established with NSW Health governing such an issue.
“NSW Health advised us that the incident did not pose any significant risk to our customers’ health given the level of treatment the recycled water receives and the close monitoring of recycled water quality,” he said.
“We immediately took steps to flush any traces of any residual recycled water from our water mains and the normal drinking water supply was restored by midnight last night.
“We certainly hope the issue did not cause any worry to the occupants of the affected households.
“While Sydney Water recommends not drinking or bathing in recycled water, the chances of becoming ill if this occurs are extremely low as the water receives the highest quality treatment and ongoing routine monitoring in accordance with NSW Health guidelines.”
Last night, Sydney Water staff door-knocked the affected households to inform customers of the matter and provided supplies of bottled water for drinking purposes.
Customers were also advised to run their taps for 10 minutes to clear their private pipes of any recycled water and discard any stored water in their fridges.
Repeat sampling of the drinking water mains and select customer taps showed that the drinking water supply was clear of recycled water by 10pm last night.
If customers have any health concerns they can contact the Western Public Health Unit on 9840 3603 from 9am today.
Recycled water is required to meet very strict quality guidelines and receives advanced treatment including microfiltration and super-chlorination in addition to the usual standard of treatment.
Sydney Water will continue to communicate to plumbers and builders working in the Rouse Hill area the importance of ensuring all work complies with the relevant standards and codes.
The organisation will also automatically provide affected customers with a form of rebate on a future Sydney Water bill.
Nov 2005 - Sidney, Aust. - Recycled Water
Sydney Water and Sydney Olympic Park Authority (SOPA) are working closely with Newington residents following detection and repair of a recycled water cross-connection in the house service pipes of two houses.
SOPA provides around 1,500 properties in Newington with recycled water, Sydney Water provides drinking water and wastewater services. The water recycling system utilises state of the art technology to produce high-quality water for properties in the area.
The cross-connections were discovered after a customer contacted Sydney Water about the taste of the drinking water. The two properties, although neighbouring, had separate and unrelated plumbing faults in the house service pipes, from the commissioning of the system in 2001 or subsequently.
While there was independent certification of the system at that time, it failed to pick up the faults – which have now been rectified at both properties.
NSW Health has advised that the incident is unlikely to pose a health risk to the customers affected, given the high level of treatment that the recycled water receives.
However, as a precaution, Sydney Water will carry out testing of the drinking water house plumbing at the remaining 1,500 properties in Newington. The recycled water system has been turned off and replaced with drinking water until the testing is complete. Already 38 houses have had preliminary testing which indicated no concerns. This testing is a due diligence measure for customers.
Sydney Water Managing Director, David Evans apologised to the residents in both homes.
Mr Evans also apologised for the cross-connection not being detected during a customer water quality enquiry in December 2002.
“Sydney Water has since then implemented new protocols, and automatically responds to all water quality enquiries in recycled water areas by checking for a potential cross-connection,” Mr Evans said.
He also noted that this was one of a range of improvements that have now been implemented in management of Sydney Water’s recycled water system at Rouse Hill.