Private well pumps and systems are designed for intermittent pressure surges. Pumps go on and off depending on pressure in the system. Pressure reaches a preset limit and the pump shuts off. As water is used pressure drops, and at a preset limit the pump turns on creating a short surge. A pump not running for a period of time due to a power loss is no different than the family leaving the home for a period of time and not using water. Unless there is some risk factor compounded by the power outage there is minimal risk of contamination during the outage.
Other factors of concern that could compound with an outage to negatively influence water safety may include:
Known system problems, such as line breaks or system leaks
Past system problems, including a history of unsafe samples
Hoses left in stock watering tanks, swimming pools, or other unsafe water sources without a backflow prevention device at the time of the outage
The loss of power disables a water disinfection system, such as a UV light or chlorination system (private well users uncertain as to the functioning of their disinfection system after the outage, or the quality of water stored during the outage, should contact a water service professional (system installer) or local health department)
The pump is damaged due to the power surge and must be pulled and replaced
Under these circumstances, testing the well for bacterial condition and disinfecting the system may be advisable. Information on well disinfection from the Department of Health and Senior Services is located at http://www.dhss.mo.gov/Lab/EnvBact/Lab-10D.pdf. (NOTE OF CAUTION: Chlorine, whether used as sodium hypochlorite or calcium hypochlorite is a strong oxidizer and should only be used strictly following label directions. Avoid skin or eye contact and after chlorination flush the system completely (preferably through an outside tap into a non-grassy area) before consuming, bathing, using for laundry, or use in an aquatic environment (fish tanks).)
All homeowners using private wells are encouraged to test the water at least once a year, regardless of any power interruption. For homeowners who do not know the past history of their well or who have lingering concerns about their water quality they may choose to have their well tested at this time.
Water testing kits and additional detailed information on well disinfection can be obtained by calling your local public health department or the Missouri Department of Health and Senior Services at 573-751-6080. - The Missouri Department of Health and Senior Services
Posted January 15th, 2007 by harminka
