Time to Disinfect a Well for Clean Drinking Water!

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Having a well for a residence isn’t difficult to maintain, particularly in instances that the ground water is shallow and doesn’t need a ton of maintenance. I’ve lived off well-water for almost 3 years now, and aside from changing the filters and checking the water softener monthly, we don’t do much for it. The best part? We never receive a bill from the city to pay for water usage! However, it’s time to disinfect the well. If you use well water, you might know it by another term; Shock chlorinating the well or bleaching the well are common terms but mean the same thing.

Why do we need to disinfect a well?

Unlike public water, residents are responsible for testing their own water for contamination. In city water, there are typically a few additives ranging from Fluoride to minimal amounts of Chlorine. Well water comes straight from the ground though, so what you see is what you get. A well is disinfected when bacteria contamination occurs. When a well is initially installed or repaired there is a lot of bacteria introduced, so the well is usually disinfected before using.

Flooding can often cause an outbreak of bacteria, so many times wells are bleached after a flood season.

It’s also impossible to not have normal bacteria in the well source – ground water innately has some dissolved minerals in it.

How to disinfect a well

So, what exactly do you use to disinfect a well? Bleach. Yup, regular ole store bought bleach without any scents or funny additives – make sure it has at least 5% sodium hypochlorite. Our well, at less than 50 feet, only requires about 1/2 gallon of bleach. The deeper and wider the well, the more water you have, and the more bleach you need. There are multiple calculators online to determine how much bleach you’ll need, so I won’t rehash that.

Once you’ve got your bleach in hand, the steps are straightforward. You’ll want to mix the bleach in a bucket with water. We’ll be using a 5-gallon bucket. Once you’ve opened up your well, pour the entire bucket back into the well.

Next, make sure that the spigot nearest the well has a hose hooked up to it. (You likely have a spigot connected to your well house.) You’re basically going to circulate the bleach into the well water. Place the end of the hose into the well, and turn it on, letting it drain into the well for several minutes – remove the hose, put the well cap back on. Now, head on inside, and starting with the faucets closest to the well turn on the faucets until you smell the chlorine from the water, then turn off. (You can also buy bleach strips to see how much chlorine is in the water.) Once you’ve completed all the faucets, turn the electricity to the well pump off.

Now comes the hard part; don’t use any water from the tap for at least 12 hours!

The next morning (or up to 24 hours later), flush your plumbing system. To avoid problems with your septic, don’t run more than 100 gallons of the bleach water into your septic. Ideally, most of the water should be flushed from hoses into a non-planted area of your property. Over a relatively short amount of time, the chlorine will evaporate into the atmosphere, but make sure it’s not going towards a stream or body of water. (If you have an ideal way to use or dispose of the chlorinated water, I’d love to hear it – we’re still trying to decide what the best method is on this!)

You can once again test for amounts of chlorine in your water once it’s flushed. Additionally, well owners will want to re-test for any bacterial contamination about a week after your well is disinfected.

Is bleach the only option for to disinfect a well?

In certain circumstances, food-grade Hydrogen Peroxide can be used to shock a well. The reality is you’ll need a lot more of it; it’s much more expensive than bleach, and you’d need to do it more often due to how quickly it degrades. The main reason we aren’t utilizing hydrogen peroxide though is because aside from the cost and necessity to repeat it more often, we already have high iron amounts in our water. Adding hydrogen peroxide would increase the amount of iron available in our water initially. Paired with the fact we’d have to re-disinfect our well several times a year, using household bleach is the most obvious choice for our small well.

Clean drinking water is important on all levels and I’m excited to not have to change our well filters quite as often soon. Have you disinfected a well before? I’d love real-life tips!


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