A Homeowner’s Guide to Well Chlorination

Sources of Contamination:

The most common causes of bacterial contamination are small animals that climb into the well past loose-fitting well caps, or surface water that infiltrates buried wells that have poor sanitary seals. Sealed and vented, state-approved well caps are readily available. But buried wells should be brought above surface level and outfitted with a sealed cap.

Overviews of Chlorination and De-Chlorination:

Note: The following assumes you have above-ground access to the well.

Chlorination introduces chlorine into the well to be circulated throughout the entire water system. In our opinion, a combination of granular and pelletized chlorine is superior to liquid chlorine because the liquid sinks. It also can become trapped in the upper portion of the well if there is a strong vein of incoming water below it.

In wells with high counts of iron and manganese, the chlorine will oxidize the minerals and cause potentially severe staining and clogging of any treatment equipment, other water fixtures, or plumbing. There isn’t much choice. But the potential problems can be minimized. This is explained below. Chlorine also causes built up “films” to be sloughed off the inside of pipes. This, too, is a potential cause plumbing and fixture issues.

De-chlorination involves running the water from the bottom of the water storage tank or an outside hose spigot until it’s clear. To determine it’s clarity, fill a five-gallon bucket or a one-gallon, translucent milk jug. The color always needs to be seen in volume, not just from the hose.

Getting Ready:

Note: The formulas below provide a 50 parts per million (ppm) residual, which is more than enough chlorine to do the job (city water has about 0.5 ppm).

Use tables #1 and #2 (below) to calculate the following:

• The gallon capacity of the well (if unknown, use 400 gallons).
• The ppms of chlorine needed (gallon capacity x 50).
• The amount of chlorine needed.

Example: 300 foot, 6” well:

• 300 feet x 1.47 gallons per foot = 441 gallons
• 441 gallons x 50 ppm = 22,050 ppm
• 22,050 ppm ٪ 52,250 = 0.42 gallons
• 22,050 ppm ٪ 180 = 122.5 pellets

TABLE 1:

TABLE 2:

• 1- gallon of Clorox bleach has 52,500 ppm of chlorine
• 1- gram pellet of chlorine has 180 ppm

The Chlorination Procedure:

1. Run a garden hose from the water storage tank (preferred) or from an outside faucet back to the well and turn it on to circulate the water.
2. Pour/drop the chlorine down the well.
3. Circulate for 20 minutes or until a chlorine odor is strongly detected, then shut off the hose and re-cover the well.
   
   Important note: if the water has a high iron/manganese content water, turning off the hose and chlorinating the house as soon as chlorine is detected can help minimize potential issues caused by the oxidized minerals.
   
4. Run water, hot and cold, one fixture at a time, until chlorine is detected. Don’t forget the toilets, the washing machine, the dishwasher, and outside spigots.
5. Let things sit for at least 6-8 hours or overnight. It’s OK to flush toilets and wash your hands. But you should minimize chlorinated water use.

The De-Chlorination Procedure:

Run a hose outside (not back into the well) where strongly chlorinated water will do the least amount of damage or harm until the water is clear and chlorine-odor free.

Important note: This can take several hours. It’s critical that you monitor the water flow to make certain you don’t run out of water. If you do, shut off the well pump at the circuit breaker and allow the well to recover.

General Tips:

• Run the hose to circulate and de-chlorinate directly from the water storage tank if possible.
• Know where your circuit breaker or pump switch is located before starting the de-chlorination process, just in case you run out of water.
• If you have an above ground “jet” pump, running out of water may require re-priming.
• Do not de-chlorinate by running inside faucets or spigots.
• Expect to lose use of the water for a full day after chlorination.
• Expect some staining.
• Expect some clogging due to released debris.

As always, please call if you have any questions. We provide well chlorination services if you’d prefer to have us do the job.