Have your public water storage tanks been cleaned lately?

 

Photo: Sediment being removed from Potable Water Storage Tank.

        The American Water Works Association recommends that tanks be cleaned at least every three years.  Recent focus on pharmaceuticals in water systems have made more people than ever aware of contaminates that may be lurking in their water supply.   Although pharmaceuticals in drinking water may be in the news the real threat is random bacteria and cryptosporidium spores.

The Threat of Bacteria-

Countless kinds of bacteria can make their way into a public water supply.  Chlorine and other treatment methods are our first line of defense.  When potable water storage tanks are clean small amounts of bacteria that survive the treatment process cycle through the system undetected and harmless due to the small quantity.  Sediment in the tank can capture and harbor these small amounts of bacteria.  The bacteria can start to grow hidden from chlorine deep in the sediment.  Chlorine can even be overwhelmed and depleted if a nitrate eating bacteria is collected.   As the bacteria continues to grow in the sediment month after month and year after year the threat to public health grows.       

  The Threat of Cryptosporidium

The threat of cryptosporidium outbreak is even greater with sediment in the floor of a water storage tank.   Again Sediment can harbor bacteria, cryptosporidium and other contaminates.  The best defense to insure a protozoa like  cryptosporidium will not take up residence in your water storage system may be to keep the tanks free of sediment.  In the Spring of 1993 over 100 people died as a result of a cryptosporidium outbreak that was directly associated with the Howard Avenue Water Purification Plant.  This was the largest water born disease ever documented in United States history.  It is estimated that over 400,000 people became ill with diarrhea.  

Due to the fact that cryptosporidium is a protozoa with a hard shell and not a bacteria the best defense to ensure it will not inhabit your water system is to make sure your water tanks remain sediment free.  This will remove and habitat that small amounts bacteria or protozoa could lodge and grow in, Preventing possible public health problem in the most simple way.  Keeping water storage tanks clean.