Water Quality

CORROSION CONTROL

Baca Water's Corrosion Control Plan | Corrosion Control FAQ page | Water Quality

Are Drinking Water Treatment Chemicals Safe?

Dave Purkiss, General Manager of Water Treatment and Distribution Systems at NSF International, responses to recent concerns raised by certain members of the community regarding the District’s use of phosphate based water treatment products. Read more...

Corrosion Control FAQ's

The Baca Grande Water and Sanitation District recently received a number of inquiries about the quality of our water and water treatment practices, please visit our Corrosion Control FAQ page for answers to many of the questions we have been receiving.

Corrrosion Control Plan

The Baca Grande Water and Sanitation District recently received a few inquiries about its water treatment practices.  As you may know, the District’s water system is a public water system, subject to state and federal regulations.  The following information addresses the District’s required Corrosion Control Plan.
Baca Grande’s water supply is derived from snowmelt from the Sangre de Cristos.  This snowmelt flows overland in North and South Crestone Creeks.  The snowmelt also percolates through the local gravels and flows westward in an unconfined alluvial aquifer.  Baca’s groundwater comes from a depth of about 100 feet below ground surface.  Chemical analyses of the groundwater show it to be very low in dissolved constituents, including calcium, magnesium, sodium, sulfate, and alkalinity.  This is a consequence of the relatively short time that the water is underground before it is withdrawn for use.

While these low concentrations indicate a groundwater uncontaminated by human activities, they also indicate that the groundwater is aggressive (corrosive) toward materials used in the construction of Baca’s potable water distribution system.  Two of the materials used in the distribution system, copper (pipe) and lead (solder) can be leached from the piping materials by aggressive water and can then enter the potable water supply.  High concentrations of copper and lead in drinking water represent a threat to the health of consumers.

Colorado Department of Public Health and Environment (CDPHE) drinking water regulations (Article 8) require Baca Water to deliver to its customers potable water that does not corrode distribution system materials.  There are four state-approved methods to accomplish this: 

Phosphate or silicate addition is typically the least-cost alternative of the four methods.  In 2008, Baca Water elected to employ phosphate addition as its corrosion control technique.  Phosphate addition was selected, in part, because it is a simple process to operate (a drum of compound and a chemical feed pump), and it is nontoxic in its diluted form.  Phosphates are important in human metabolism, as phosphate is the major mechanism for energy storage and utilization at the cellular level.  Phosphate is also an essential plant nutrient (the nitrogen:phosphorus:potassium ratio [N:P:K] is listed on every plant fertilizer).  Phosphates are also found in many foods and drinks; for example, the amount of phosphate consumed in a single cola soft drink greatly exceeds the amount of phosphate ever consumed in drinking water.  For example, Coke contains about 70 mg of phosphorus which is equivalent to a concentration of 0.6 mg/L phosphate, almost twice the applied dosage of phosphate corrosion inhibitor and perhaps ten times greater than the residual concentration of phosphate in the Baca potable water.

Phosphate dosage is controlled at the lowest possible residual concentration required to attain copper and lead concentrations below CDPHE requirements.  The dosage originally used in 2008 was insufficient to control copper and lead concentrations in the potable water system, and has been gradually, but slightly, increased over the years.  Recent Baca Water copper and lead sample results demonstrate the corrosion control program is working, with copper and lead concentrations below regulated limits.  In addition, the phosphate residual concentration is extremely low, signifying that the majority of the phosphate compound is bound up in the protective phosphate scale, and that phosphate is not present in significant concentrations in the drinking water.

In summary, Baca Water treats the aggressiveness (corrosivity) of our relatively pure groundwater to protect its customers from the toxic effects of copper and lead that would dissolve into the drinking water if corrosion control were not practiced. 

Thank you for taking a moment to read this information.  If you have any questions regarding Baca Water’s corrosion control plan, water quality, or any other questions concerning the District, please contact the District office (719.256.4310).

Sincerely,
Board of Directors
Baca Grande Water and Sanitation District