Treatment Process

  • Tulsa's main water sources are Lake Eucha, Lake Spavinaw, and Lake Oologah. Water is brought from the treatment plants or reservoirs through two pipes called flowlines that are 53.9 miles and 52.2 miles long. Each flowline is made from concrete, and is up to 8 inches thick, and 4 1/2 to 6 feet deep.
  • Water is drawn from the lake by these flowlines and is pumped to the water treatment plants by pump stations.
  • Upon entering the water treatment plant, debris transported through the flowlines from the lakes is filtered out through coarse screens.
  • The water then travels into a "Rapid Mix" where Aluminum Chlorohydrate and cationic polymer are added as coagulants. The coagulated particles in the water cling together and form larger particles, called floc, in a process called flocculation.
  • After mixing, the water and the floc flow into a sedimentation basin. Here the floc settles to the bottom and is pumped from the water to sludge thickening basins for disposal. The clarified water flows over weirs at the end of the clarifiers (or basins). At this point, roughly 95- 97% of all suspended particles present in the water have been removed. 
  • From the sedimentation basin, the clarified water is then carried to the filters for removal of any remaining particulate material. The filters are comprised of sand and granulated activated carbon (GAC). GAC effectively removes taste and odors that may be present due to naturally occurring organic material in the source water. 
    Fluoride is then added to reduce tooth decay, and a small dose of chlorine is then added to the water to ensure inactivation of any bacteria that might have survived treatment process and keep the water safe as it travels to homes and businesses throughout the area.
  • The water then flows to large, underground storage tanks, also known as clearwells. Sodium hydroxide is added to the water at this point to ensure stability of the water for corrosion control in the distribution system. The clearwells are constructed with baffled walls throughout the entire tank which forces the water to travel in a serpentine pattern. This provides a means for adequate mixing and contact time with the chlorine for proper disinfection.  
  • Finally, the water is then pumped into the distribution system to meet customer demand which varies throughout the year. Ammonia is added to the treated water just as it leaves the treatment plants and enters the distribution system. This process is known as chloramination. The ammonia binds to the chlorine in the water, which greatly reduces the potential for the formation of harmful disinfection byproducts in the distribution system.

The Drinking Water Treatment Process is of interest to people of all ages. The following graphic is useful when simplifying the steps that are taken in the treatment process.
Note the source lakes depicted at the top of the cartoon, and our two drinking water Treatment Plants, A.B. Jewell and Mohawk.

Steps 1-5 describe the basic events of the treatment process.

Step 6 indicates that the water is pumped from the treatment plant to Tulsa customers as well as many rural water districts and neighboring communities.

The graphic also depicts some of the water storage towers located around Tulsa. The water levels in these storage towers are constantly monitored at the treatment plants. Operators watch these levels to be sure that the towers are filling with new water at about the same rate as they are being emptied out by consumers.


Taste and Odor Issues
In the last decade, the City of Tulsa has spent millions of dollars to get rid of taste and odor problems in our drinking water. The water comes from Lakes Eucha and Spavinaw, two of the city's three primary sources for water.

What causes these taste and odor problems? The high growth rates of certain algae in these lakes has caused these taste and odor problems. When there is too much phosphorus in a lake, too much algae grows. These plants release chemicals as a natural part of their life cycle. It is those chemicals that affect the taste and odor of our water.
So where does this phosphorus come from? Runoff from land around the lakes brings in this extra phosphorus. Phosphorus is a natural chemical nutrient primarily found in fertilizers and in animal waste. As water travels downhill in the watershed, it picks up and carries nutrients like phosphorus from the surface, the soil, and from where it has seeped underground. Studies conclude that extra phosphorus has accumulated in these watersheds.

What has caused this accumulation? These same studies show that the excess phosphorus has built up primarily from years of using poultry waste as a fertilizer in farming operations. Over the years, companies have built more and more poultry operations in Oklahoma and Arkansas, in the watershed for Lakes Eucha and Spavinaw. This means that more and more birds create more and more poultry waste every year. Until recently, most of that waste was applied within the area as a fertilizer.

In recent years, the poultry industry has been required to reduce the amount of poultry waste used as fertilizer within this area. But farmers are still applying the waste. Any additional waste adds to the existing problem. No one knows how many years it will take for run off to flush the existing phosphorus through the watershed. It may be many years before phosphorus levels in the lake return to normal so that extra treatment to eliminate taste and odor problems is not required in Tulsa's water.