A drinking water warning was issued by the Sioux City Water Supply company on March 6th, 2017 wherein residents within the Grandview pressure zone of the Sioux City Water Supply were warned to boil their water before using.

The notice was issued due to the water system violating a drinking water standard for contact time on March 6, 2017 as a result of problems with filter valves and was set to remain in effect until March 7, 2017 in case the water contained disease-causing organisms.

Contact time means that in order to ensure proper disinfection, water in the treatment plant must be in contact with chlorine or a similar disinfectant for a minimum amount of time in order to ensure that all bacteria as well as organisms such as viruses and parasites are killed – this did not occur for a short period of time on March 6, at the Sioux City Zenith Water Treatment Plant.

Inadequately treated water may contain disease-causing organisms including bacteria, viruses, and parasites which can cause symptoms such as nausea, cramps, diarrhoea, and associated headaches. The amount of “contact time” necessary depends on the amount of disinfectant in the water and the temperature of the water.

Under this type of warning, residents of the affected areas are advised to make sure that they do not drink any water without boiling it first and are instructed to:

  • Bring all water to a boil;
  • Let the water boil for one minute, then let it cool before using it;
  • Alternatively use bottled water

Under this type of restriction, boiled or bottled water should be used for drinking, washing dishes, brushing teeth, making ice, and food preparation until further notice.

Infants, the elderly and Individuals with severely compromised immune systems may be at increased risk and should seek advice about drinking water from their health care providers.

The problem was quickly resolved and adequately disinfected water was being pumped to the system by late morning of March 6th. Steps were also being taken by the City to prevent a recurrence of this problem in the future.