Quick Answer
The optimal chlorine dosage for a 200-gallon well is between 1-2 milligrams per liter (mg/L), which is approximately 0.5-1 chlorine tablets or 1/4 to 1/2 teaspoon of liquid chlorine. This dosage is typically used for shock chlorination, which is a process of disinfecting a well by adding a high dose of chlorine.
Understanding Chlorine Dosage
When it comes to chlorinating a well, the goal is to achieve a free chlorine residual (FCR) of at least 1 mg/L. However, this can be challenging, especially in wells with high levels of organics or iron. To determine the optimal dosage, you need to consider the well’s water temperature, pH, and total organic carbon (TOC) levels.
Calculating Chlorine Dosage
A common method for calculating chlorine dosage is to use the following formula: mg/L = (Number of Chlorine Tablets x 3.2 mg/L) / Total Gallons of Water. For example, if you add 1 chlorine tablet to a 200-gallon well, the calculation would be: 1 x 3.2 mg/L = 3.2 mg/L, which is equivalent to 1.6 mg/L per 100 gallons. To achieve a 1 mg/L FCR, you would need to add 0.8 chlorine tablets.
Shock Chlorination Techniques
Shock chlorination involves adding a high dose of chlorine to the well to disinfect the entire system. This process typically requires adding 2-5 times the normal dosage, depending on the well’s condition and the level of contamination. It’s essential to follow the manufacturer’s instructions for the type and amount of chlorine to use, as well as to ensure the system is properly vented and the well is drained before treatment. Additionally, it’s recommended to test the FCR after treatment and wait 30 minutes to 1 hour before drinking the water.
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