Shocking a well is the most effective method to restore flow and water quality when a private water supply begins to run slow or run dirty. This process, often called a shock chlorination, involves introducing a high concentration of chlorine down the borehole to eliminate biofilm, bacteria, and mineral precipitates that cling to the walls. Homeowners and well owners typically turn to this procedure after noticing a drop in yield, a strange taste, or following nearby construction or flooding.
Understanding Why Wells Need Shock Treatment
Over time, any well that draws water from the ground will accumulate biological and mineral deposits. Iron bacteria, for example, create a slick biofilm that traps sediment and reduces the diameter of the pipe. Even though a pump might be running, the water struggles to flow through this clogged system. Shock treatment breaks up this matrix, dissolving the obstructions and allowing the aquifer to feed the pump again. It is a necessary maintenance step rather than a repair for mechanical failure.
Preparing for the Shock Process
Before introducing chemicals, you must verify the well’s structural integrity. Check the casing for cracks and ensure the cap is tight to prevent surface contaminants from entering. You will need to calculate the volume of water in the pipe to determine the correct amount of chlorine; this usually includes the pipe itself and the pressure tank. Safety is paramount, so wear gloves and eye protection, and ensure the area is well-ventilated to dissipate any gases released during the process.
Calculating Volume and Chemical Dosage
To calculate the volume, measure the depth of the well and the internal diameter of the pipes. You are essentially trying to figure out how many gallons of water are sitting static in the system. Once you know the volume, you can apply the standard shock ratio. For most residential wells, a ratio of 500 parts per million (PPM) of chlorine is recommended to sanitize the system effectively. Using a high-quality granular calcium hypochlorite or a liquid sodium hypochlorite ensures a strong oxidizing potential.
Step-by-Step Shocking Procedure
The execution requires a careful sequence to ensure the chlorine reaches every part of the system. You should not simply dump the chlorine into the tank and hope for the best. Instead, you need to create a closed loop that forces the chemical to travel to the end of the borehole and back.
Step 1: The Introduction
Turn off the power to the pump to prevent it from starting unexpectedly. Mix the chlorine solution in a large container according to the calculated dosage. Attach a hose to the pump’s suction head, which is the opening where the water enters the pump. If the pump is submerged, you may need to remove the cap on the well head or use a bailer to lower the hose deep into the casing.
Step 2: The Circulation
Run the solution down the hose until it reaches the pump. Then, reattach the power and allow the pump to push the chlorine back into the holding tank. Let the system run until you can smell chlorine strongly at the kitchen tap. This indicates the biofilm has been breached and the chemical is flowing through the entire network. If you cannot smell chlorine at the taps, you may need to adjust the dosage or repeat the process.
Post-Shock Flush and Recovery
Once the chlorine smell is consistent, you must remove the chemical entirely. Allow the pump to run until the chlorine odor dissipates significantly. Do not drink this water during the flushing phase, as the chlorine levels will be too high. Collect the output in a clean container until the taste and smell of chlorine are gone. Test the water afterward to ensure the bacterial count is zero before using it for consumption or cooking.
