Environmental Issue & Sick Building Syndrome Blog

The Economic, Chemical and Political Challenges of Providing Safe Municipal Water

April 2nd, 2016 10:38 PM by Dan Howard

         The process of treating water differs across the country depending upon the source of the water, the contaminants found in the water and the chemistry required to make the water safe. The problem is that the source water chemistry can change or become intermittently contaminated by industrial discharges and events such as floods, algae and other contaminations that can occur from time to time.

            The nature of many water authorities is that they work with serious budget and staff constraints that often make monitoring and identification of problems difficult. That in turn makes response and solution of problems economically and politically difficult

The Stages of Water Treatment

Pre-Treatment: Water enters the system. Depending upon the source, dirt or sand may be removed from the water. If subject to algae growth, some chemicals may be needed.


Coagulation: Chemicals are added so that smaller suspended particles clump together and fall to the bottom of a settling tank. That coagulated junk is called floc. The water has to settle for a longer time in this step than in the pre-treatment stage.          


Clarification or Sedimentation: Water slowly flows through the next step. This results in sludge at the bottom of the basin. That material will be removed and then disposed.


Softening or Stabilization: Minerals such as magnesium and calcium need removed from the water to avoid damage to the municipal system and residential pipes and fixtures.


Filtration: This is the step where the suspended materials are removed. The remaining products can make the water look cloudy. Cloudy appearance is referred to as “turbidity”. These small particles can include microorganisms, protozoa cysts, algae, silt, iron and other organic and mineral products. Yummy! Sand, gravel, garnet or similar materials are used for this step.


Fluoridation and disinfection: This is the important last step before water is pumped to a holding tank. The most common disinfectants are chlorine based chemicals.


Water is the pumped up to the holding tank: Water pressure is the result of gravity. The difference in elevation between the level of water in the tank and the open spigot in your home determines the pressure of the water. The pressure is ½ PSI for every foot of difference in that height. 


Click for download of full PDF article      http://goo.gl/BM9Skv

Posted by Dan Howard on April 2nd, 2016 10:38 PM



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