You’ve tested your well water for coliform bacteria and it has come back positive. Now what?
Most strains of coliform bacteria won’t cause problems and are perfectly safe. The problem is that there are some forms of E Coli that are very dangerous and fecal coliform are all unsafe to drink.
Time to bring out the big guns and get to work shocking your well. If you want to know how to remove coliform bacteria from your well water, then this is the most effective method.
There are also other bacteria like iron and sulfur bacteria that are not a health threat but are the cause of that rotten egg smell common in well water. This method will take care of them too.
If you haven’t already tested for coliform you can use one of the tests listed below before you think about shocking your well to be sure what contaminants you are dealing with.
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48 to 72 hours
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24 to 48 hours
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In this article:
How To Shock A Well With Bleach
Before I get into the tips for how to proceed, let me say that this and other types of well disinfection procedures should be done with the thought that you’re not going to have drinking or bathing water for a while.
In the case of shocking with bleach, plan to do this procedure when you won’t be needing any water for at least 24 hours.
Before you get started
If You Have Water Filters In Use
Make sure that if you are using any filters that they be bypassed so the media in them doesn’t get ruined by the bleach.
What Type Of Bleach To Use
Your ordinary household bleach is fine but it should be 5.25% chlorine to be effective but also less damaging to the well and your fixtures.
Also, make sure you aren’t using any scented type of bleach.
How Much Bleach To Use
One gallon of bleach will treat up to an 8-inch diameter well containing 100 feet of water. Check this chart below to see exactly how much water your well will have so you know how much bleach you’ll need.
|Casing Diameter||Well Depth||Well Depth||Well Depth||Well Depth|
|0 to 50'||50 to 100'||100 to 200'||200 to 300'|
|4"||8 ounces||16 ounces||24 ounces||1 quart|
|6"||1 quart||2 quarts||1.5 gallons||2 gallons|
|8 to 12"||1 gallon||1.5 gallons||2 gallons||2.5 gallons|
|12 to 16"||1 gallon||2 gallons||4 gallons||6 gallons|
|20 to 24"||2 gallons||6 gallons||10 gallons||14 gallons|
Time needed: 23 hours and 59 minutes.
Shock Chlorinate Your Well With Bleach | Step By Step
- Be Safe
Get yourself rubber gloves, safety goggles and a chemical resistant apron.
- Mix The Solution
Check the chart above for the amount of bleach to mix half of the recommended amount with 10 gallons of water in a ten gallon bucket or bigger; pour into well without the pump operating. Make sure you pour it in a way that it comes in contact with the sides of the well to maximize the exposure of the solution with the bacteria that may be on the casing.
- Bypass Filters
Hopefully you’ve bypassed your water filter if you have one. This goes for whole house filters or even the point of use ones.
- Get Water To All The Fixtures
Turn on a faucet and wait until you smell the bleach. Turn it off and do the same at another faucet. Open all the fixtures one by one including the shower, bath and outside faucets and flush the toilets.
- Circulate The Water
Attach a hose to the outside faucet and run the open end of the hose into the well casing. Turn the water on so that you can circulate the water through the well for about 15 minutes.
- Add The Rest Of The Bleach
Mix in the other half of the bleach in a bucket with 10 gallons of water. Pour it into the well without pumping.
- Now You Wait
Let the bleach mixture sit in the well for at least 12 hours but 24 is better. Don’t drink or bathe in this water at all.
- Flush It Out
Run all of your fixtures until the smell of bleach has disappeared or at least is barely noticeable.
While you are letting the water runoff, try to avoid the waste water from entering your septic system. Also, don’t let any of the outside faucets run the water towards any vegetation or garden as the bleach water will kill your plants.
You will likely have some chlorine left in the water for up to a week. You’ll want to use a chlorine filter to get rid of the chemical. It is safe to drink at this point, but it is best to avoid drinking it or bathing in it.
You can read all about the side effects of chlorine and how to remove it by clicking that link. It is a pretty detailed article and will answer any questions you have about chlorine in your drinking water.
Well Water Test
WaterSafe Well Water Test Kit
Specifically designed to help you test quickly and easily for: iron, copper, lead, bacteria, pesticides, nitrates, nitrites, chlorine, pH and hardness.
If there is a source of contamination that persists then you may be getting bacteria in your well again. Make sure that you test your well again after a few weeks. If it is positive again you will need to find the source of the contamination. Call a well water expert at this point to check out your well.
If you don’t have any bacteria after a few months then you should be fine. Continue to test once per year to make sure.
How To Shock A Well With Chlorine
The same step by step guide above is the exact same method to use for shocking a well with chlorine to remove bacteria.
The only difference is how much chlorine to use. A 100-ppm chlorine concentration is ideal for sanitizing a well. Dry pellets are most commonly used to shock a well with chlorine. Something like Well Safe are the most common among well owners and work very well.
|Casing Diameter||Gallons of Water Per 100 Feet||Recommended Ounces of Dry Chlorine|
|8 to 12"||260||5.1|
|12 to 16"||590||11.6|
|20 to 24"||2350||46|
Make sure that you add the pellets to the water before adding to the well water. Don’t put the pellets into the bucket and then add water as it will cause a reaction that could send you some toxic fumes. Adding the pellets to the water will avoid this.
Alternatively, if you are a well owner you should look into a chlorinator system so you can easily shock your well when needed. Some well owners like to shock their well once per year to be on the safe side.
Since there are other things that can contaminate your well, this system is great because you can use different solutions to disinfect. All you have to do is load up the tank with whatever disinfectant solution is called for and then run the pump. Mixing is easier and safer when you use a chlorinator system.
Frequent testing and the possibility of needing to shock your well every year or two is something that comes with the responsibility of owning a well, unfortunately.
FAQ About Shock Chlorination
Yes, it is possible to use too much bleach. In fact, too much bleach can corrode the metal parts in your well and lead to damage with the well not functioning properly. Also, the chlorine will linger in your water and you may need to filter the water for a while while testing periodically before the parts per million are low enough to not be a problem.
If you hire a company to do it, it can cost anywhere around $100 depending on where you live. Doing it yourself will only cost as much as the chlorine, 10 gallon bucket and the safety supplies to do it. If you buy a chlorinator system, then the initial cost is in the hundreds of dollars but you’ll have an easy system to use for years to come without ever needing a professional.
You should be testing your well once per year and shocking according to what the test results say. If they come back as safe to drink every time, then you don’t need to shock your well at all. If you want to feel safe, then every 3 to 5 years is good enough unless your tests do come back as being contaminated.
You likely have some heavy metals in your water with the most likely culprit being iron. You’ll need to use a well water test for heavy metals to see if that is why your water is turning brown after using bleach or chlorine.
If you are thinking of shocking a well for coliform but are intimidated then I hope this article has shown you that it isn’t as scary a thought as it seems.
Of course, you do need to be careful and take precautions as it can be dangerous when you are handling chemicals like chlorine. With some preparation, patience and this guide, you can make sure that your well is safe for you and your family.
If you have any questions about this or need some clarification, then drop a message in the box below. I’ll get back to you ASAP!