Section R. 325.1661 - Disinfection of well and pumping equipmentRule 161.
(1) After thoroughly pumping to waste pursuant to the provisions of R 325.1639(5), a well and pumping equipment shall be disinfected with chlorine that is applied to obtain a chlorine concentration and minimum contact period specified in table 5 in all parts of the water supply system before pumping the well to waste and flushing out the chlorine solution. A well drilling contractor or pump installer shall be responsible for chlorinating that portion of the water supply system on which work has been performed. Table 5
Minimum Chlorine Concentration and Contact Time
Amount of Chlorine Added to 100 Gallons of Water
| Chlorine Minimum Concentration (Parts per Million) | Gallons of 5.25% Sodium Hypochlorite (Liquid Bleach) | Pounds of Dry Hypochlorite (Granular) | Calcium Contact | Time |
| 100 ppm | 1/4 gal | 0.14 lbs |
| 10 hr |
| 250 ppm | 1/2 gal | 0.35 lbs |
| 4 hr |
| 500 ppm | 1 gal | 0.70 lbs |
| 2 hr |
| 1000 ppm | 2 gal | 1.40 lbs |
| 1 hr |
(2) Before placing a new, repaired, or reconditioned water supply system into service, and after all traces of chlorine have been flushed out, 1 or more water samples shall be collected from the sampling faucet. Organisms of the coliform group shall not be present in the sample or samples.(3) The water supply owner shall be responsible for collecting the water sample or shall arrange for the owner's designated representative to collect the sample. The well drilling contractor or pump installer shall notify the water supply owner of the owner's responsibility for collecting the water sample.(4) A well driller or pump installer is not required to redisinfect a well or pump as a result of water samples that are collected from a location other than the sampling faucet required pursuant to the provisions of R 325.1658.Mich. Admin. Code R. 325.1661