Well water safety information

- provided by Cumberland County Department of Health

Flooding or damage of a well due to hurricanes, floods, heavy rainfall, or other natural disasters is a condition that can cause bacterial contamination of the well. To assure your drinking water is safe, the following precautions should be taken:

If your well has been damaged:

Consult a NJ-licensed pump installer or well driller in order to repair the well and to conduct Disinfection Procedure as per guidance from the Centers for Disease Control and Prevention.

If your well has been flooded:

If you have to cook, brush your teeth or give water to pets, before you can get a coliform bacteria test done, you should use a temporary means of disinfecting the well.

Methods of Temporary Disinfection

1.                  Boiling the Water - If there is known or suspected contamination, the water from the well should be brought to a complete and vigorous boil for one minute (not including the time it takes to come to a complete boil).  This is a simple and effective way of providing immediate disinfection for small quantities of water.  It does not provide treatment, however, to all the water in the well or the water in the distribution system.

2.                  Chlorination - If a well is temporarily contaminated by coliform bacteria, disinfection is accomplished most effectively with a chlorine-containing chemical.  Any common household liquid bleach that contains approximately 6% "active" ingredient, usually sodium hypochlorite, is the most convenient chemical to use.  The following table shows the proper amount of liquid bleach to be added directly to the well.



                            (Disinfectin Strength Approx. 50 ppm.)

DIAMETER OF WELL                                      WELL DEPTH





  50 ft.

100 ft.

200 ft.

up to 6"

4 ounces

6 ounces

8 ounces

10 ounces

20 ounces

32 ounces


16 ounces

24 ounces

32 ounces

 2 quarts

3 quarts

4 quarts


2 quarts

3 quarts

4 quarts





2 gallons

3 gallons

4 gallons




In the case of shallow dug wells, the chlorine solution can be added directly to the water by simply raising the cover, whereas the seal on existing driven and drilled wells must be removed first.  After adding the solution, make sure that the well seal or cover is properly replaced.

Allow the chlorine solution to remain in the well for at least six hours, or preferably overnight.  After this period of time, open a tap and let water run to waste until the odor of chlorine is detected.  Close tap and let the chlorinated well water remain in the distribution system for at least one hour.  Then let water run until the odor and taste of chlorine is no longer noticed.  The water may now be used for all general household purposes except drinking.

To assure its safety for drinking the well water should now be tested for coliform bacteria.  Allow at least 24 hours before taking the sample.  This will assure that all the water in the well has been replaced with fresh water from underground sources.

The test will indicate the effectiveness of disinfection.  If coliform organisms are still present, this suggests that the ground water is continuously contaminated.  In this case, the "one-shot" or temporary method of disinfection described above is not adequate. You should contact a licensed well driller to evaluate your well and determine if a permanent method of treatment, a repair or a new well is required.

Some Local Certified Testing Laboratories (others may be found on-line or in the yellow pages)

Vineland Environmental Lab
782 South Brewster Road, Suite B1
Vineland, NJ 08361
(quoted $375 for a home well test)
Cape Environmental Laboratories
824 N. Broadway
W. Cape May, NJ 08204
Q C Incorporated
1835 W Landis Ave
Vineland, NJ 08360
South Jersey Water Test LLC
4077 S. Black Horse Pike
Monroe Township, NJ 08094
Toll Free:  866-875-3505
(quoted $100 for a home well bacterial test for private owner purposes).