Specialists in water, wastewater, and shellfish analysis.   STEP-BY-STEP INSTRUCTIONS | CHLORINE SOLUTION CHART A well system should be disinfected whenever you construct, repair, or accidentally contaminate a water system. Pour "no-name" household bleach (5% chlorine) into your water system. Check the appropriate amount on the following chart. Wait approximately 1 hour for the bleach to mix in the water column in your well. Keep in mind that the bleach solution will only disinfect the inside of the well up to the existing water line. Open all taps in the house until you smell the chlorine solution and then turn off taps. This way, you are effectively disinfecting the entire water system. Open the valve or plug at the top of the pressure tank just before stopping the pump to allow the solution to contact the entire inside surface of the tank. Then, close the valve or plug. Let the chlorine solution sit in your water system for a minimum of 24 hours. Do NOT drink, brush your teeth, bathe, or do laundry during the entire 24 hours. Bleach is an irritant and the concentrations used for this process can cause severe reactions. It is only safe to use and flush the toilets during this period. Pump out the majority of the bleach solution using an outside tap and garden hose onto a grassy area. Do NOT discharge into a ditch or stream, as this will kill anything living in the water. Pump out the bleach solution until the chlorine odour disappears. The amount of time this takes (hours to days) is dependent upon the recovery rate of your well at the time. Be careful, especially if you have an above-ground pump, not to run your well dry. We recommend waiting a minimum of 10 days, preferably after a rainfall event, before re-testing. This allows the well to resume a more natural state after shocking (treatment), and to see if it is a reliable source of drinking water. Factors such as cloudiness, high levels of iron, manganese, and hydrogen sulphide will limit the effectiveness of the chlorine to disinfect a system. In extreme cases, this process may need to be repeated. The BC Ministry of Health Services advises that private water systems (wells) be monitored for bacterial contamination a minimum of twice a year. Typically, the worst time of year for bacterial contamination of wells is immediately after the first rains in the fall. DIAMETER OF WELL CASING AMOUNT OF BLEACH PER WELL WATER DEPTH Inches Centimetres Per 10 Feet Per 3 Metres 4 10 4 teaspoons 20 mL 6 15 10 teaspoons 50 mL 8 20 7 tablespoons 100 mL 10 25 10 tablespoons 150 mL 12 30 13 tablespoons 200 mL 24 60 3.5 cups 800 mL 36 90 2 quarts 2.3 L 48 120 3 quarts 3.4 L 60 150 5 quarts 5.7 L 72 180 7 quarts 8.0 L TOP | BACK | HOME Copyright © 2003 North Island Laboratories Ltd. All rights reserved.