Water Treatment Plant

Step 1: Screening and oxidation of organics

Water is taken directly from the river through intakes upstream of the Water Treatment Plant at a rated capacity of 350 million litres/day (MLD) (92.5 million gal/day (MGD)). Three pumps are available to pump water directly to the Water Treatment Plant. We also have a secondary intake at the Water Treatment Plant that includes a screen chamber building and pump house. Both sites have emergency power to provide raw water to the Water Treatment Plant as a backup during power failures.

These new intakes are highly efficient and are designed with industry leading technology meeting all regulatory standards.

Step 2: Ferric sulfate coagulation and water softening

When the raw water reaches the Water Treatment Plant, potassium permanganate is added to address taste and odour problems with raw river water.

The water then enters the sand separator units to remove suspended sand particles before entering the clarifiers.

The water then enters the clarifiers, where it is mixed with ferric sulphate and lime. Lime reacts with the hardness in the water to form insoluble carbonates and hydroxides that settle out in the process. The hardness due to calcium and magnesium is reduced from approximately 180 to 120 mg/L as CaCO₃.

Ferric sulphate reacts with particles in the water and the lime to coagulate into a large particle (floc) which becomes heavier than the water and settles out.  This process is called floculation.

The concentration of floc in the clarifiers is carefully controlled and maintained as a dense circulating slurry. The clear water is drawn off the top of the slurry. Excess sludge is flushed back to the Residuals Management Facility. Water quality is monitored under these carefully controlled conditions.

Step 3: pH adjustment and the addition of chlorine and fluoride

Immediately after clarification the pH is adjusted down to approximately 8.4–8.6. This maximizes the effect of chlorine and ensures the water is not corrosive to the distribution system. Chlorine and fluoride are then added prior to entering a large chlorine contact basin.  Chlorine disinfects the water  as the water travels through the settling basin allowing the chlorine to have adequate contact time to disinfect the water. Fluoride helps to reduce tooth decay. The contact basin provides the necessary time for disinfection reactions and further clarification through settling.

Step 4: Filtering

The water is then filtered through dual media filters (sand and crushed coal [anthracite]). The filtration rates are carefully controlled in attempts to maintain water turbidity of less than 0.1 NTU. The filtered water is collected in a clear well after it flows through the filter.

Following filtration, ammonia hydroxide is added. The ammonia combines with the free chlorine (previously added) to form chloramines. Chloramines have a lower disinfection capability than chlorine but remain active for a much longer period of time. They also give off less taste and odour than chlorine. This extended activity permits disinfection to continue throughout the distribution system.

Step 5: Transfer Pumping and UV disinfection

The filtered water is then pumped across to the new Ave H Disinfection and (2015) and pump station where it travels through medium pressure UV lamps designed to inactivate viruses and bacteria.

Step 6: Chlorination and Chloramination

After the UV system chlorine is again added to provide further disinfection. Water then travels through a series of baffles through two reservoirs to allow for chlorine contact time.  Water is retained from 4 to 8 hrs in the reservoir before ammonia hydroxide is added.   The ammonia combines with the free chlorine (previously added) to form chloramines. Chloramines have a lower disinfection capability than chlorine but remain active for a much longer period of time. They also give off less taste and odour than chlorine. This extended activity permits disinfection to continue throughout the distribution system.

Step 7: Distribution Pumping

The high lift pumps (maximum of 2000 HP) draw the treated water from a pump well and pump it to the distribution system. The pumps maintain a pressure of 690kPa or 100psi in the domestic water lines that they feed. The high lift pumps also move the water to the reservoirs.

Step 6: Storage in reservoirs

The City of Saskatoon currently has two water reservoirs, for use when the demand is greater than the plant output. They are located on Acadia Drive and on 42nd Street. These two reservoirs are filled by the high lift pumps and have their own pumps to supply pressure to the distribution system.  When pumping out of the reservoir, each reservoir has a pumphouse to pump water back into the distribution system.  The pumps in the reservoirs can also be used as booster stations to continue to supply water at the appropriate pressure to the City.

Highly trained plant operators in the control room closely monitor all aspects of the Water Treatment Plant, twenty-four hours a day, seven days a week. The on-site laboratory continuously tests the processes to ensure that the water going to the public meets or exceeds environmental standards.

What is left over?

Residuals from the backwash water, filters, clarifiers, and chlorine contact basin go to two sumps in the basement of the facility. Residuals are concentrated in a thickener where the residual is concentrated by removing water in a similar process to the clarifiers. The concentrated residual is pumped to two filter presses where the remaining water is pressed out of it.

The solid filter cake is removed and hauled by truck to the Saskatoon Landfill. The water from the thickener and the filter presses are returned to the back wash water sump. This water is pumped to a clarifier in the facility where clear water comes off the top and is dechlorinated before it is returned to the river, the sludge produced from this part of the process is returned to the residuals sump.

The City's Water Treatment Plant exists to provide a dependable and adequate supply of safe, high quality, potable water to its customers. Under normal operating conditions, the supply meets the following criteria:

• All conditions specified in the provincial Permit to Operate.
• Water hardness does not exceed 160 mg/L (as CaCO₃.).
• Fluoride concentrations meet Water Security Agency guidelines.
• Hourly demands are met with a minimum pressure of 38 psi at the main 93 percent of the time. Daily demands plus fire flow demands are met at a minimum pressure of 20 psi.
• Fire hydrants meet the minimum requirements of the Fire Underwriter's Survey 99 percent of the time.
• Water consumption is metered in accordance with American Water Works Association (AWWA) standards.
• In the event of interruption in normal water supply, the following criteria are met:
• Following notification of a main break, normal service is restored within 24 hours in 95 percent of the occurrences and an alternate source is provided within 8 hours in 98 percent of the occurrences.
• During treatment plant failures, storage volumes can sustain a rationed supply for 48 hours.
• During a major city-wide power outage, standby equipment can sustain average annual consumption demands.

Water is supplied to SaskWater Corporation, within the terms of a Master Water Supply Agreement and in accordance with the City Policy C09-018 (Potable Waterline Connections), to serve water users outside the City's boundaries.

Water Treatment Plant: 220,000 m³/day
Spur Dike Raw Water Pumping Station: 575,000 m³/day
Water Treatment Plant Raw Water Pump Station back-up capacity: 100 million L/day
Filter Capacity: 278,000 m³/day
High Lift Pumps: 431,000 m³/day (combined)
Low Lift Pump: 310,000 m³/day
High Lift Standby: 163,000 m³/day

Reservoir Capacities

42nd Street Reservoir

Capacity: 30 million L
Pumping Capacity: 81,000 m³/day

Acadia Reservoir

Capacity: 45 million L
Pumping Capacity: 145,000 m³/day

Avenue H Reservoir

Capacity: 15 million L
Pumping Capacity: water treatment plant pumps

An automatic control system is closely monitored and controls chemical dosages in proportion to the incoming raw water flow.

The process control system is currently being upgraded in conjunction with the many process and capacity upgrades at the Water Treatment Plant. The computer interface provides a window to the operational process and allows the operator to control filter back-washing, pump start/stops, chemical dosage changes, and numerous other routine operational functions. The computerized system also provides remote pumping and storage facilities, controls, process alarming, data logging, and reporting functions.

A computer-based plant security system using security card access and monitoring cameras is currently being upgraded. All activity is monitored from the Water Treatment Plant control room using multiple security cameras, door monitors, and computer logging.

The Water Lab maintains accreditation by CALA to ISO/IEC 17025, and that accreditation is limited to those tests on the laboratory's scope of testing. The laboratory staff and chemists conduct over 50,000 water quality tests a year, using state-of-the-art equipment, to ensure that Saskatoon’s drinking water is clean and safe. The following is a summary of the services provided:

• Monitors drinking water quality to ensure it is of a consistently high quality.
• Provides laboratory services necessary to support the operating and monitoring requirements for the Water Treatment Plant.
• Responds to consumer water quality concerns.
• Monitors water quality of distribution system and watershed.
• Provides services to Capital and related environmental programs.

The Water Treatment Plant adheres to the highest standards as set out by the Water Security Agency.  As part of those standards, the City of Saskatoon is required to report once a year to consumers about the quality of water produced and supplied from the Water Treatment Plant.     The Drinking Water Quality and Compliance Report details the various water quality compliance standards within the Water Treatment Plant's Permit to Operate, and the related water sample results.

Dosage Ranges for Chemical Feed Operation

Parameter	Optimum	Limits
Lime	55-65 mg/L	30-70
Ferric Sulfate	45-55 mg/L	40-70
Ammonia	1.7-2.2 mg/L	2.4
Chlorine	2.5-3.5 mg/L	2-5
Fluoride	0.7-0.9 mg/L	1.2
Potassium Permanganate	0.3-0.4 mg/L	0.25 - 0.80
Carbon Dioxide

Is Saskatoon's water safe to drink?
The Environmental Services Branch and Water and Wastewater Treatment Branch have comprehensive testing programs in addition to carrying out the required testing of the Water Security Agency. Over 21,000 tests are performed each year on plant, reservoir and distribution system samples. Saskatoon's drinking water meets or exceeds all Canadian Drinking Water Quality Guidelines as well as Saskatchewan's Municipal Drinking Water Quality Objectives.

Who develops Drinking Water Guidelines?
Guidelines for Canadian Drinking Water Quality are developed by Health Canada in cooperation with the health and environment ministries of the provinces and territories. Municipal Drinking Water Quality Objectives, containing constituent objectives specific to Saskatchewan, are also established by the Federal Provincial Advisory Committee on Environmental and Occupational Health.

What water quality standards does the Water Treatment Plant have to meet?
Staff regularly check over 93 different physical, chemical, microbiological, and radiological parameters in order to meet the National Guidelines for Canadian Drinking Water Quality. Numerous critical water parameters are monitored on a continuous basis. Over 21,000 tests are carried out every year. Refer to the Drinking Water Quality and Compliance Report under Related Documents for more information. 

What is the likelihood of water contamination?
Extremely low. In repeated testing, Canadian drinking water has been found to be among the best in the world. Sensitive tests have been developed that can detect contaminants in water in concentrations as low as a few parts per-trillion (one part per-trillion is equivalent to one second in 320 centuries!). By treating drinking water we have virtually eliminated diseases such as typhoid and cholera.

What is Cryptosporidium and/or Giardia and how might they affect the consumer?
Cryptosoridium and Giardia are single - celled, parasitic organisms that may be found in source waters. They originate from the intestinal track and wastes of warm blooded mammals (humans, beavers, deer, and cattle) and may be washed into surface water supplies. The organisms exist in surface water as dormant cysts which are extremely resistant to traditional chlorine disinfection. If present in the treated water, they may cause flu-like illnesses such as diarrhea that can, in the case of cryptosporidiosis, become life-threatening in the immunocompromised, the elderly, and the very young. The symptoms usually appear one to four weeks after a significant number of cysts have been ingested (30-50 cysts per 1000 litres of water). In order to prevent these organisms from entering the water distribution system, it is necessary to protect and control the water shed, ensure water treatment processes are well operated and monitored, and proper distribution system maintenance procedures are in place and followed. The Water Treatment Plant monitors for these cysts on a regular basis; and to date the organisms have not been detected in the treated water.

What is my water pressure?
The water pressure at the Water Treatment Plant is maintained at 690 kPa (100 psi) throughout the year. However, distribution system pressures vary based on factors such as the contour of the land (the higher you are, the lower your pressure will be), and the system water demands. During the summer months in periods of high demand, system pressures can drop to 275 kPa (40 psi) as a result of the losses caused from pipe friction in the distribution system due to high water velocities.  [cos_token:contact_info]

Why is my tap water cloudy?
Tap water appears cloudy due to the dissolved air in the water. Cold water contains more dissolved air than warm water when the water enters your home. It warms and releases the dissolved air and bubbles are created. These bubbles cause the water to appear cloudy and are an aesthetic concern only. To deal with this concern either leave your tap run for a short while or fill a container and let it sit for a while and within minutes the bubbles will disappear.

How am I billed for the water I use?
Water bills are calculated based on your water meter’s recorded consumption and the size of your meter.

What causes large increases in my water bill?
There may be several reasons for an unusually large water bill: high consumption due to additional appliances (dishwasher), added lawn or garden watering, leaking plumbing fixtures, a billing adjustment from an actual meter reading after several months of estimates, or reconciling a meter read with the remote reader. [cos_token:contact_info]

What chemicals are added to the water?
A total of eight chemicals are used in the treatment process, each having a very distinct purpose in water purification. Three chemicals are added to ensure a residual level exists when leaving the plant; chlorine and ammonia for disinfection, and fluoride which helps in the prevention of tooth decay. The remaining chemicals used are: potassium permanganate, ferric sulfate, and quicklime.

What is being done about the aluminum in our drinking water?
Aluminum in drinking water has become a very emotional and contentious issue over the last few years.  Prior to January 2000, the City of Saskatoon had an aluminum residual level of approximately 0.6 mg/L arising from the use of aluminum sulfate in the coagulation/clarification stage of treatment. In January, 2000, the City began to use ferric sulfate as an alternative coagulant. The outcome of this process change is lower residual aluminum in our finished water (approximately 0.031 mg/L). Other than lowering the residual aluminum, all other water quality characteristics will remain the same.

What level of chlorine is in my drinking water?
Chlorine is added to our drinking water to ensure a residual of approximately 1.7 mg/L when the water leaves the treatment plant. The residual chlorine level is necessary to provide continued disinfection throughout the distribution system.

Do I need to dechlorinate the water for my fish tank?
Since Saskatoon’s water contains chloramine as opposed to free chlorine, it cannot be readily removed by leaving the water sit or by bubbling air into it. Dechlorination tablets, readily available at most pet stores, are required for chloramine removal.

Why is fluoride added to the treatment process?
Fluoride is added to our drinking water to maintain a level of approximately 0.7 mg/L in order to assist in the prevention of tooth decay. Health Canada and the Saskatoon Health Region strongly recommend fluoridation of Saskatoon's drinking water at a rate of 0.7ppm, which has now become the North American recommended standard. The fluoride used by the City is certified by the National Sanitation Foundation and the American Water Works Association.

What is the hardness of Saskatoon's tap water?
Saskatoon’s raw water supply has a hardness of approximately 180 mg/L. Through the treatment process, it is reduced to about 160 mg/L (expressed as Calcium Carbonate). Saskatoon’s water is considered to be moderately hard.

Should I consider a home water softener?
Since Saskatoon’s water is 160 mg/L of hardness, a water softener is not considered necessary. However, the degree of hardness a person tolerates is a matter of personal preference. Water softeners typically replace nontoxic hardness minerals with sodium which may be a concern for those on sodium restrictive diets if the cold water is softened.

Should I buy a home water purifier?
Water produced by the City’s Water Treatment Plant meets all, and in most cases is better than, rigorous national drinking water quality standards. If not properly maintained, home purification and/or filtration systems can actually cause water quality problems. A carbon type filter may be beneficial for those allergic to chlorine but frequent filter changes must be made to prevent bacterial problems from developing. Determining if a water purifier or filter would be beneficial is a personal decision.

Should I buy bottled water?
If you want a drink with different taste you may want to try bottled water, but the costs are approximately 1,000 times as much as your tap water. The bottled water industry is less regulated than municipal water treatment plants. Water produced by the City’s Water Treatment Plant meets all, and in most cases is better than, rigorous national drinking water quality standards.