Rules & Regulations of the State of Tennessee
Title 0400 - Environment and Conservation
Subtitle 0400-45 - Division of Water Resources
Chapter 0400-45-09 - Water Well Licensing Regulations and Well Construction Standards
Section 0400-45-09-.12 - DISINFECTION OF WATER SUPPLY WELLS

(a) A chlorine solution shall be placed in the well in sufficient dosage to produce a chlorine residual of at least one hundred (100) parts per million (ppm) in the water standing in the well (see Tables C and D for the correct amount). A chlorine solution may be prepared by dissolving dry hypochlorite granules (trade names include HTH, Chlor-Tabs, etc.) in water or by liquid bleach (trade names include Clorox, Purex, etc). (CAUTION: When working with chlorine, persons should be in a well ventilated place. The powder or strong liquid should not come in contact with skin or clothing. Solutions are best handled in wood, plastic or crockery containers because metals are corroded by strong chlorine solutions).

TABLE C

QUANTITY OF DISINFECTANT REQUIRED TO PRODUCE A FREE CHLORINE RESIDUAL OF 100 PARTS PER MILLION (PPM) IN DRILLED WELLS.

Click to view Image

Measures: 2 cups=1 pint (pt) 7 tablets=1 ounce (oz)

2 pints=1 quart (qt) 8 ounces=1/2 pound (lb)

4 quarts=1 gallon (gal) 16 ounces=1 pound (lb)

Equations for calculating amount of disinfectant required to chlorinate drilled wells with diameters larger than 8 inches:

Pints of liquid bleach=D2 h ÷ 10

Ounces of dry granules=D2 h ÷ 9

where: D=Diameter of well in feet

h=height of water above bottom of well in feet.

TABLE D

QUANTITY OF DISINFECTANT NEEDED TO PRODUCE A FREE CHLORINE RESIDUAL OF 100 PARTS PER MILLION (PPM) IN DUG OR BORED WELLS

Click to view Image

Equations for calculating amounts of chlorine needed to disinfect dug or bored wells.

Pints of liquid bleach=D2h)10

Ounces of dry granules=D2h) 9

where: D=diameter of well in feet

h=height of water above bottom of well in feet.

(b) Place the required amount of liquid bleach or dry granules in the well by one of the following methods:

(c) Agitate the water in the well to insure thorough dispersion of the chlorine throughout the entire length of the well.

(d) The well casing, pump column and any other equipment above the water level in the well, shall be thoroughly rinsed with the chlorine solution as a part of the disinfecting process.

(e) The chlorine treated water shall stand in the well for a period not less than twelve (12) hours. The well shall, thereafter, be pumped until the odor of the chlorine is no longer detectable.