NEHA Hurricane Response Guide

Hurricane Response Guide for Environmental Public Health Professionals

Emergency Well Disinfection Steps 1. Determine your Standing Well Volume (SWV) and assess the general water quality of the well. 2. Use the tables below to calculate the required amounts of white vinegar and chlorine bleach (min.

5.25% sodium hypochlorite) based on your SWV and water quality. Disinfection Quantities for Average Well Water Quality NO sulfur, low-to-moderate bacteria and hardness Standing Well Volume (gallons) pH Control (white vinegar) Food Grade

Chlorine Required, min. 5.25% (Sodium Hypochlorite)*

500 100 150 200 250 300 350 400

1 ½ cups

1 cup 2 cups

3 cups 1 quart

2 ½ cups 3 ½ cups

5 ½ cups 6 ½ cups

1 quart 5 cups 6 cups

8 cups

½ gal + 1 cup

½ gal + 2 ½ cups 7 cups *Amount of hypochlorite should be at least 5.25%; however, most household bleach now contains 8.25% sodium hypochlorite.

Table adapted from wellcare information on Disinfecting Your Well . Disinfection Quantities for Difficult Well Water Quality HIGH bacteria, iron, hardness, and sulfur Standing Well Volume (gallons) pH Control (white vinegar) Food Grade

Chlorine Required, min. 5.25% (Sodium Hypochlorite)*

500 100 150 200 250 300 350 400

5 ½ cups

3 ½ cups 6 ½ cups

½ gal + 2 ½ cups

1 gallon

½ gal + 2 cups ½ gal + 5 ½ cups 1 gal + 1 cup 1 gal + 1 quart

1 gal + 5 cups 1 ½ gal + 2 cups

2 gallons

2 gal + 5 cups

1 ½ gal

2 ½ gal + 2 ½ cups

1 ½ gal + 3 cups

3. Switch OFF power to the pump and put the water treatment equipment into bypass mode. 4. Remove the well cap and pour the required amount of vinegar followed by chlorine into the well. Be sure to pour in one continuous flow, avoiding electrical connections and pitless adapters. 5. Switch the power back ON. 6. Attach a clean hose to a nearby faucet, place the other end into the well, and recirculate the chlorinated water for 1 hour to wash down the well casing and pump piping. Turn off the hose and recap the well. 7. Open each indoor faucet until a strong chlorine odor is detected, then shut off each one.

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