Well Water Testing
By: Eddie Ayers, County Extension Agent
For the most part, north Georgia has had an abundance of rain this winter. As of the middle of February we had received over 12 inches since January 1st. As of the third week in February we had received over 15 inches of rain. Our average for the year is 62 inches, so if this pattern keeps up we will once again have abundant rain. Hopefully flooding has been minimal, but so much rain does bring to mind the importance of well safety. Wells that were overtopped by flood waters need to be flushed and tested for bacteria because of the potential danger of contaminants being washed into the well. Water from wells that has had a change in color as a result of the rain should also be checked.
UGA Extension Water Resource Management and Policy Specialist Gary Hawkins recommends pumping and flushing a minimum of 2 or 3 times the well volume to clear the system. This water should be discarded from an outside faucet and not from an inside faucet to bypass the home’s septic tank. After pumping the water, the well should be shock chlorinated. The well should be flushed again until there is no smell of chlorine bleach and, like before, the flushing step should be done through an outdoor faucet to bypass the septic system. This highly chlorinated water, if discharged to the septic tank, could cause problems with the bacterial colonies in the septic tank.
After the well is shock-chlorinated, flushed and the chlorine smell is gone (about two weeks), the well water should be tested for bacteria. Families can get their well water tested using their local county UGA Extension office for $46. Until the test for bacteria comes back, Hawkins strongly suggests that water for cooking or drinking be boiled before consumption. If the well still contains bacteria, the report will explain in detail how to treat the well.
To calculate the volume of water that should be pumped from a well, use the following calculation. Most of the well casings in this area are 6 inches so the factor for that size is 1.47. That means that there are 1.47 gallons of water for every foot in depth. Multiply the depth of water in the well by this factor to determine how much water is in the well. If your casing is not 6 inches, contact me in the Gilmer County UGA Extension office and we can get the right factor.
There are several methods to determine how much water you have flushed out, but the one that I use is to calculate how long it takes to fill a 5 gallon bucket. Divide that time by 5 to get the output per minute. Using this figure you can determine how many minutes you need to run the water to flush the number of gallons of water that was determined in the previous calculation. A couple of methods can be used to determine the depth of water in a well. If you can see the water in the well, lower a heavy object tied to a string down the well and measure the length of the string until you see the object touch the water. In a deep well, lower a heavy object like above until you hear the object hit the water and measure the length of string. If you cannot see the object hit the water, another way (but less accurate) is to drop a small stone into the well and count or time the seconds it takes for the stone to hit the water (you will have to listen closely for this.) Multiply the number of seconds by 32.2 and that will let you know how far the water is below the surface. Knowing the depth of the well and the depth from surface, subtract the two to get the height of the water column for calculating the volume of water in the well.
An example of this calculation is if you have a well that is 300 feet deep and the water level is 25 feet from the surface, subtracting 25 from 300 equals 275 which means you have 275 feet of water in the well. Multiply 275 by 1.47 to get the gallons in the well. That figure is 404.25 gallons. Using a factor of 3 pints per 100 gallons, you would need to apply a little over 12 pints of chlorine bleach in the well.
If you have any questions about this process or for more information on well water testing, contact me in the Gilmer County UGA Extension office.
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