You need to test your well on an annual basis. Contact Watson Company for instructions on when and where to take the sample. If the results show the presence of bacteria, then you should shock chlorinate your well. It should be done on a yearly basis without knowing if bacteria is present or not. This will insure that the well remains in a safe condition. This can be done with household laundry bleach. Take a 5 gallon bucket and add 1 to 2 quarts of bleach add water and mix well. Pour down the well making sure that it coats the pipe casing wall. Using this formula for every 50 feet of standing water in the well. Turn on the outside hose and circulate water down the well until the smell of chlorine appears then continue for at least 10 minutes. Turn off the hose and open all faucets in the house until the smell of chlorine appears. Shut the system off and let set for at least 12 hours. Flush the system until the strong odor of chlorine disappears. This may have to be repeated. Do not run strong chlorinated water into septic. If bacteria still exists, you may have to install a continuous chlorination system and UV system. You may contact our company for more information and literature on this process.