Questions & answers on how to shock or disinfect a drinking water well:

These questions & answers on well shocking, disinfection, or chlorination will help troubleshoot the procedure for building owners or service providers who need to disinfect a water well.

This article series explains how to shock a well, when, why, and exactly how to chlorinate a drinking water well.

We provide a table explaining the quantity of bleach needed to disinfect a well, and a table comparing the 3 Common Well Water Disinfectants: Chloramine, Chlorine and Chlorine Dioxide.

Page top sketch illustrating both deep and shallow water well construction and depths is provided courtesy of Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [ carsondunlop.com ].

Questions & Answers on How to Shock or Chlorinate a Well

Recent questions & answers on how to sanitize a well, posted originally at WELL CHLORINATION & DISINFECTION - be sure to see the procedures and advice given there.

On 2018-12-08 by (mod) - how to get bleach into the well

You can try getting into the smaller diameter line that's the one that sends water down the well although perhaps either of them would work.

However if there's a foot valve or check valve in the well it may not except fluid poured through the pipe.

On 2018-12-07 by Rich

I want to sanitize my well - 2" driven sand point 36 ft deep - cannot easily access the well head which is buried 4 ft below ground - have a 2 line jet pump, 1-1/4" and 1" lines -

Can I break into one of these lines and pump bleach down one of them.

On 2018-11-05 by (mod) - how long to flush out the chlorine after shocking a well

Assuming that the only chlorine source is your well shocking procedure (that is you don't have a permanently-installed chlorinator or disinfection system) then It's safest to flush the chlorine until you do not smell it in the water supply.

If you're having trouble doing that the procedure may have been performed improperly, using the wrong chlorine source (tablets), or you may need to drain a water heater and water pressure tank.

On 2018-11-05 by Debbie

Is my water safe to drink if I still smell chlorine after shocking my well

On 2018-10-14 by (mod) - how to get bleach into the well

you may be able to remove pressure, open the well piping and insert the disinfectant that way

On 2018-10-14 by Kenny

My we'll head has the pressure switch and a seal down about a foot or so with the wires coming up thru it ...so can I still shock the well some other way or what

On 2018-05-22 by (mod) - I dropped chlorine tablets in the well

Good question and one that comes up often, Todd.

When we have trouble flushing chlorine out of a shocked well I suspect

- overdose with chlorine

- use of solid chlorine tablets that are sitting at the well bottom

- chlorine treated water is residing in water tanks or hot water heater tank that need to be flushed

On 2018-05-22 by Todd

Why is it taking so long to drain the bleach out of my well?

On 2018-04-04 by (mod) - important to calculate the amount of bleach or disinfectant needed to shock the well

Dana

Was this a hand dug well or a well bore?

Who calculated the proper amount of chlorine?

Did chlorinated water get into the water tank and water heater?

If this was a drilled well,

Try draining those tanks and then flushing the system again.

On 2018-04-03 by Dana

I am in the process of selling my childhood home. As part of the inspection, they wanted us to treat the thirty foot deep well.

We poured in a gallon of bleach per county orders. Unfortunately, we discovered several busted pipes when it was time to flush it out.

The bleach was in the well for several days. Since that time, we have ran the water for the specified time twice to remove the bleach, but we can still smell it. Please help, the inspection is in two days.

On 2018-01-17 by (mod) - I dropped chlorine tablets in the well

Anon

The result would be a continuing smell of chlorine in your building's water supply and at very high levels, possible health concerns; at lower levels, surprising bleaching effects when doing laundry.

At high levels the corrosive effects might harm equipment.

None of that has to do with clogged filters. More likely your well water level is lower, or there is a casing damage that's dropping soil into the well, or the pump or foot valve is too low in the well.

On 2018-01-17 by Anonymous

...if the chlorine was not flushed out properly (I did follow the instructions for doing so) what would the result be? An increase in sediment?

A change in the performance of the Kinetico system? The softener? The filter?
We are looking for reasons why the drastic change in the duration of our filters. Thannks for your reply!!

On 2018-01-16 by (mod) - I dropped chlorine tablets in the well

No,

Chlorinating a well would not itself kick up sediment, though dropping tablets into a well can make flushing chlorine out quite difficult.

The tablets fall to the bottom of the well and may not dissolve promptly.

Using tablets to "shock" a well is a bad idea. Use liquid disinfectants for better results and for easier flush-out of the disinfectant later.

On 2018-01-16 by John Mason - Kinetico dual tank system

My home was built in 1999/2000. We have a Kinetico dual tank system as well as a filter and softener. Late summer 2017 we had a persistent (but not awful) sulfur smell in our water.

I dropped chlorine tablets in the well, and followed the online instructions procedure to the letter.

Before this we changed our filter about every three months, now we have to change them monthly when the water pressure drops. Did the chlorination "kick up" more sediment in the well?

On 2017-12-21 by Joe - cl2 in my well will it react with my nutrasul chemical hydrogen peroxide

If i put cl2 in my well will it react with my nutrasul chemical (which is hydrogen peroxide) that i treat my water with in my house.

On 2017-11-30 by (mod) -

Ron,

You may never smell bleach at the tips if your well is deep, and has a large static head, because the concentration of bleach in your well maybe to dilute to be effective. You might want to take a look at this article

inspectapedia.com/water/Well_Chlorination_Shocking_Procedure.php

on how to shock or sterilize a well because you need to calculate how much bleach is necessary.

On 2017-11-30 19:16:29.179342 by Ron

After adding a gallon of bleach to my well how long should it take before I can smell the Clorox in the house coming out of the spigots

On 2017-09-19 00:19:12.468409 by Chris

Yes my dad has poured a gallon of bleach...down our well! Now it taste like bleach and smells how do i get it back to normal? I cant drink or cook with it

On 2017-09-11 22:39:07.459666 by (mod) -

No worry, my phone and computer have their own ideas about what I should be typing as well.

If you've had a successful coliform bacteria test at a well that was very difficult to sanitize then I would not assume that the system is sanitary until I had waited at least a few days, preferably a week, to allow residual bacteria to propagate again in the well - if they're there - in order to be detected.

If that follow-up test is clear then you can be more-confident about the well - regarding bacteria - but you should test again in 6 months or a year and annually thereafter.

Keep in mind that coliform is also an indicator that surface water has been getting into a well (often, not always), so that means that any other surface contaminants (pesticide, fertilizer, etc) could be present. Discuss that with your water test company.

On 2017-09-11 22:15:55.507798 by Anonymous

Ellen again, sorry but test was for coliform, not chloroform.

On 2017-09-11 22:07:29.561423 by Ellen

After getting a positive test back for chloroform we have had to chlorinate our well x 4 before getting a clear chloroform result. The well hadn't been taken care of for years and had a leak for about a month prior to being fixed. are we safe to assume all good with our drinking well water now?

On 2017-08-25 17:38:47.115735 by (mod) -

You may need to chlorinate the water downstream from the UV system, at a sufficient concentration and for a sufficient time. If I were just sweating in a replacement pipe section in a water supply line I'd probably not worry about it, or if I had a reason for concern I'd find it easier to chlorinate the new pipe before installation.

Above at Continue Reading you'll find the procedure for WELL CHLORINATION & DISINFECTION Chlorination won't harm the UV system.

Watch out: a well water system that has sediment needs filtration and might if the water is hard also need softening - to slow the accumulation of debris on the UV light that will render it ineffective.

Also most UV lights come with instructions recommending an annual replacement of the bulb.

Also, and this is most important, while the "no-e coli" suggests that your well water isn't contaminated with effluent from a sewage or septic system, to me (and your water lab should confirm this view), when we find coliform in a well we know that the most-common source is surface water or surface runoff that is entering the well.

In that case ANY contaminant on the surface (road salt, pesticides, etc) that is or was nearby can be in the well. The coliform test is a high-level screening test. It is absolutely not a guarantee that there are no other contaminants in the well. Further water tests are probably in order.

On 2017-08-24 by mongo

I recently bought a home,,well failed for total coliform..no e coli or fecal..sellers to install UV and retest before closing..I have some simple plumbing repairs to do myself. replace a leaking copper pipe and a galvanized drain line..how do I disinfect my work as not to contaminate the system ? also I can have the well chlorinated with the uv system ..with by passing the uv..then put the uv back on line ?? thanks..

On 2017-12-09 by (mod) - we put in chlorine but we never smelled it in our water

Rees

"a full gallon" is an arbitrary amount of bleach. The amount you need depends on the quantity of actual water in the well when it is at rest - the static head.

Details are at PROCEDURE & QUANTITY of BLEACH NEEDED to SHOCK A WELL https://inspectapedia.com/water/Well_Chlorination_Shocking_Procedure.php#ShockTable1

On 2017-12-08 by Rees

My water never smelled like or tested positive for chlorine after 90 minutes of running a faucet, even though we put in a full gallon. We poured it down the vent pipe, since the wellhead would be difficult to remove (due to age-related rust), and it took about 15 minutes for it to drip through a funnel.

Do we need more chlorine?

Or is the chlorine not making it into the well?

[Photo blelow posted by reader Rees]

On 2017-10-31 12:55:06.883199 by (mod) -

Anon,

Thank you for your comment.

Since this health authority-recommended well chlorination procedure is the most widely used one worldwide, it would be most helpful if you could give us a citation, scholarly article, or other source to support the view that there are reasons why it shouldn't be used, as well as What alternative should be considered.

On 2017-10-30 16:04:39.207096 by Anonymous

do not use this method. it is ineffective and could do damage to your pump and well

On 2017-10-0 by Frances Donovan

We have a top of the line water filter system but have had a sulphur odor coming from the cold water tap in our downstairs kitchen, only at this tap. The kitchen was renovated about 6 years ago. I have researched about shocking our well with hydrogen peroxide in the form of NutraSul.

We read that you can pour up to 4 gallons of this into our well ( whichis not low on water), leave the product over night, and turn on the garden hose on our shore rocks in the morning until the product is flushed out. We just recently had our septic system over hauled and it is fine. We are thinking of doing this procedure in the spring. Is this safe for our system ? Thanks.

On 2017-09-19 by Steve H

Is it possible to chlorinate/shock a shallow well with this set up:

Single line jet pump with a pressure tank.
Well cap must be buried in the crawl space, and the crawl space has a concrete floor.

There is a 1 1/4" steel pipe that comes up through that concrete floor about 8" into a 90 degree elbow with an adapter that is clamped to the black plastic suction line.

The suction line then runs up into the laundry room where it is then clamped to the back flow preventer, which is attached to the jet pump. The pump sits on top of the pressure tank.

I can't seem to find any information on chlorinating a well set up of this type. I am guessing it is a old/outdated set up as most other cottages in the neighborhood have deep wells with recognizable well heads in the front yards.

I was thinking I might be able to chlorinate the well by closing the system to the house, and then removing the elbow in the crawlspace to drop the chlorine down that portion of the suction line?

A little uneasy about doing that though.

I'm looking to eliminate iron bacteria

Thanks for any help

On 2017-08-03 14:42:11.888668 by Gary

In a house pre-purchase well inspection coliform was found. The seller is going to 'shock' treat the well. The septic system at this house is a peat based for the drain field. This house is not completely finished and the plumbing pipes in two bathrooms and the kitchen are capped off.

I have a couple of questions if you are able to help:

1. Is the chlorine shock treatment of the well damaging to the peat based septic system?

2. Since some plumbing pipes are capped off will the shock treatment be able to clean the water in those pipes or will another shock treatment be needed when those pipes are eventually connected?

I do understand the source of the well contamination must be found and corrected.
Thanks!

 

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