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Well depths and types (C) Carson Dunlop AssociatesWell Chlorination Diagnostic Q & A #2
How to shock a water well

  • POST a QUESTION or COMMENT about well shocking or well sterilization procedures: how to deal with bacterial contamination in drinking water wells

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 ].

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

Questions & Answers on How to Shock or Chlorinate a Well

Unsanitary well opened by owner, needs to be shocked and sealed (C) Daniel Friedman

Recent questions & answers on how to sanitize a well, posted originally at WELL CHLORINATION & DISINFECTION or at the comments section at the bottom of this page.

On 2019-11-26 - by (mod) -

As you're reading this article series The amount of Clorox bleach that you need depends actually on the true volume of water in the well that's being shocked plus of course the volume that's in your house piping water tanks at cetera.

On 2019-11-26 by Campbell's

We've used 2 gallons of Clorox . We've been running the water now for a hour. No bleach smell yet ?
We've done this before and it didn't take this long..
?

On 2019-03-27 - by (mod) -

I'm not sure either, Courtney. If someone drops soild chlorine into a well it can be a devil of a time flushing that out; If you dosed the well properly but still smell chlorine now, try emptying out any tanks that contain water such as the water pressure tank and water heater. (Take care not to turn on an electric water heater that's empty as it'll be destroyed)

On 2019-03-25 by Courtney

We used well safe to shock chlorinate our well. Let it sit 12 hours and are now trying to flush the chlorinated smell out. We have ran our outside house/faucet I bet a total of 20 hours over the last 2 days. It taste better than initially but still has a faint bleach smell. How long will I need to run the house to get rid of the chlorinated smell!

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]

Well pit photo contributed by reader Rees (C) InspectApedia.com 2017

On 2017-10-31 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 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!

On 2017-05-03 by Chris

Preliminary results of a total coliform bacteria test came back positive a week or so *after* that arbitrary half-gallon-of-bleach treatment that DEC recommends. Water ran clear of the cloudiness I described for a while but kept producing and is still producing black sediment that I'm told is iron.

Cloudiness returned shortly after I collected the sample that tested positive for coliform bacteria. I'm planning to first chlorinate the well with scent-free household bleach in quantities determined according to the procedure you describe here.

The level of the well has been near the surface, as the spring thaw is just ending after two weeks and the ground is snow free but just starting to fall below saturation.

I can't really conclude that the well has a persistent source of bacterial contamination until I chlorinate it correctly, so that's what I plan to do first. I'm still suspicious that the saturated groundwater causes surface contamination of the well, and I need a sanitary well cap.

Thanks again for all the information.

On 2017-04-12 by (mod) -

Do keep us posted, Chris. What you learn will help other readers.

With due respect to the Alaska DEC's pamphlet on "water purification", those instructions are for small quantity disinfection and by absolutely NO means do they produce "pure" water that could be assured to be free of all contaminants or pollutants.

Disinfecting water addresses specifically bacterial contaminants only.

On 2017-04-12 by (mod) - re-posting advice from Alaska DEC on water purification

RE-posting

I understand now. I was operating on general advice from the Alaska DEC according to this document [Alaska DEC on "water purification], but it makes sense that I would want the amount of bleach to correspond to the amount of water in my well.

After running the water for an hour after letting the bleach sit in the system for a day, the water has returned to its light brown/yellow color. I also noticed some sediment in the bottom of a glass I poured, which of course makes sense since I temporarily removed the sediment filter. I will try running the water again this evening for awhile in an effort to stabilize the water before I test, then let you know what i come up with. Thank you!

On 2017-04-11 by (mod) -

Chris,

I don't think anyone is suggesting that regular coronation of a well is required in the way that you describe, nor that it would be effective. If it's necessary to shock a well the quantity of bleach that's needed depends on the volume of water in the well. Arbitrarily using a half gallon does not procedure that would make me confidence that the water was safe to drink

Color contamination of well water can be from any other variety of sources besides bacterial contamination which would be the target of bleach. My suggestion is to collect a representative sample of your water and have it analyzed by your local water test lab. Let me know what you're told and we can take it from there.

On 2017-04-11 by Chris

Before shocking my well tonight, I failed to consider that I can't smell anything at all with the cold I currently have. I even tried smelling the bottle of bleach afterward and could not smell it.

That said, after living here for four years without understanding that I should have been treating the well twice a year with a half-gallon of bleach, the problem became apparent when my water turned brown/yellow and changing the whole house sediment filter didn't fix it. So I poured the half gallon of bleach down the well casing, per Alaska DEC guidelines

. I ran water from the garden hose back down the casing until I heard the well pump kick on a second time.

I flushed the toilet and ran cold water from all faucets until the water turned rusty brown. (Water in back of toilet was a dark, rusty brown as well.)

My question is about the hot water faucets. I ran a 1.5 gpm sink faucet nearest the incoming water until the well pump kicked on to fill the pressure tank three times, but the water is still not nearly as dark rusty brown as it is coming out of the cold water faucets.

Is it safe to say I should run the hot water faucet until it's the same rusty brown as the cold water faucets, which incidentally are all still producing this dark rusty water up to this point? My concern is that I'll flush too much of the bleach without treating. Thank you.

On 2017-03-23 by (mod) - I did a well water treatment 2 days ago and after running all the chlorine out the water is now brown. What should I do?

Jennifer

It's possible that a volume of water that you ran to flush out the bleach or will sanitizer was so great that you've exhausted your well. That can cause the water if the water in the well is causing the sediment pick up.

I would suggest waiting 24 hours, and seeing if the brown clears up. If it does not I would have a sample analyzed by a water test lab. If you do that let me know what you're told and we will think about the next step.

On 2017-03-23 by Jennifer

I did a well water treatment 2 days ago and after running all the chlorine out the water is now brown. What should I do?

On 2017-03-06 by (mod) - When should we re-test our well water?

Quoting from the article WELL CHLORINATION & DISINFECTION

Retest the well water after all the Clorox or chlorine is out of the system and the water has been used for 5-7 days (typical health department guideline) or 7-10 days (my suggestion) after the disinfection.

The longer you wait until the well water retest the more valid will be the results, because you are giving time for a remaining bacterial contaminating colony to reproduce. We elaborate on this point at "When to re-test your well water" below.

On 2017-03-04 by Anonymous

We treated our well 10 days ago I was fixing to test our water & husband told me he smelt bleach 2 days ago but none since. When should we test our well water?

On 2016-12-15 by Sarah-Lee Terrat

After shocking a well, how long do you wait until you re-test your water?

On 2016-06-23 by (mod) -

Curious; I'd flush the well to clear water;

On 2016-06-23 by Kieran

The water is 50' deep in a 6' pipe, I used normal household bleach.

When I ran the taps it was smelling so strong I was having trouble breathing, in the morning there was no smell at all. Previous to the treatment the water turned brown and settled into stringy bits at the bottom with an oil like slick on the surface and a smell a bit like battery acid.

The water now turns brown, it settles a little and has a slight film on the surface, it is pretty much as it was only much less severe. Maybe I haven't fully killed it?

On 2016-06-23 by (mod) - I put a gallon of bleach in my well, today there is no chlorine smell

I can't guess Kieran, since we don't know how much water received that gallon of bleach nor the bleach concentration strength. Bleach in water is volatile and will dissipate, but in a well casing, at a quantity sufficient to disinfect, typically you'd smell bleach until flushing the well.

On 2016-06-23 by Kieran

Last night I put a gallon of bleach in my borehole, circulated the water until it was stinking and left it for the night. Today there is absolutely no smell of chlorine, is that normal, does the chlorine evaporate?

On 2016-05-17 by (mod) - how do I disinfect my water heater?

If you are just treating the water heater, and put it on bypass, the other plumbing system components won't be involved nor affected. I'd try that.

Also see the details at WATER TREATMENT EQUIPMENT DISINFECTION

On 2016-05-16 by Anonymous

I have a oil hot water heater which of course is my hot water, (summer winter) do i need to bypass the heater all together and also the water softener, and whole house water filter?

On 2016-05-10 by (mod) - how much chlorine to cure a torten egg smell

Anon:

If the rotten egg smell is due to a temporary bacterial infection of the well follow the tables given at WELL CHLORINATION & DISINFECTION.

The amount of disinfectant needed depends on the volume of water in the well, so there is not one single "right" answer.

if the rotten egg smell is from sulphur in the water supply, shocking the well won't fix the problem.

On 2016-05-10 by Anonymous

How much coring would you put in your well at one time time rid your water of the rotten egg smell

On 2016-04-13 by (mod) -

OK

Indeed plumbing materials are not kept in sterile conditions before they're inserted into a well, that's why SOP is to shock a well after working on it.

If the only contaminant source was one introduced by working on the well

1. it should be cured by proper well shocking procedure

2. it would be odd for that to be causing a dead animal smell

On 2016-04-13 by Kathy

Yes we have been happy with the hand pump and it meets our needs but I believe we may have introduced the contaminates when we installed the pipe for hand pump.

The well was capped with no pump when we bought the place. We installed the simple pump ourselves and then had water tested. It was not stinky water that we recall when we were doing this.

We had it tested for sulfate which was 10 mg/L, fluoride, chloride and some other inorganics, also tested metals ( aluminum,calcium, magnesium, manganese, potassium, sodium, and zinc) and then the microbiological which was the total coliforms and e-coli.

Also nitrogen, solids and pH. Solar pump for the simple pump setup will not pump deep enough. I think we will have to have a professional probably come shock it. I do not know if our Berkey water filter would take care of what we need to be able to drink it without doing something to the well

On 2016-04-13 by (mod) -

OK so the bore depth is 405 ft. and water rises in the bore to a top height of 278 ft from the bottom.

Thank you for the reference to Sunshine Works - I stand CORRECTED: I was mistaken about the limits of hand pumping. According to Sunshine, their hand pump can lift water from depths. Quoting:

"With the standard 24 inch handle, the hand-operated Simple Pump requires very little force to operate and easily pumps 5 gallons per minute from depths to about 200 feet, delivered at normal household water pressure of about 50 psi."

www.sunshineworks.com/stainless-steel-deep-well-hand-pump.htm

Sunshine also provides solar powered pumps.

Keep in mind that the flow rate of any pump, hand or powered, will diminish as the depth is increased.

Good to have no e-coli, but coliform in the well is still not acceptable, and in my opinion it's also a hint that any other contaminants on the ground surface could be in the well, since coliform in wells most-often gets there from surface runoff entering the well or its aquifer. If you only tested for "bacteria" you might find just coliform but you're not testing for other things like sulphur.

So we have two concerns: bacteria and odor. You might check with your test lab to cover just what was the scope of testing you had done, and whether the lab can test for common odor sources like sulphur or iron-loving bacteria.

Have you also inspected the well and well cap to convince yourselves no critter fell in?

On 2016-04-13 by Kathy

We actually purchased a simple pump from Sunshine Works - the pipe drops down about 325'. According to well log, static water level was 278'. Total depth is 405' not 465' I stated earlier. We had water tested and the only concern was coliforms present per 100ml - no e-coli. The pH is 7.3.

On 2016-04-13 by (mod) -

Kathy:

Thoughts on smells in water in an off-grid water well.

Stinky well water may be due to any of a variety of causes: sulphur, a dead animal, iron-loving bacteria, something else. Start by having your water tested for common contaminants; otherwise one cannot possibly know what are the hazards of, nor the remedies for smelly drinking water.

As you can read in WELL CHLORINATION & DISINFECTION, you will need to calculate the proper amount of bleach to properly and safely sanitize a well. Doing a half-baked guess increases the risk of either illness from bacteria or trouble getting rid of excess chlorine in the system.

Your water filter itself can become contaminated and serve as an odor or bacteria reservoir.

Although your well is 465ft deep, you cannot possibly be pumping by hand from that depth. A hand pump cannot lift water more than about 25 feet.

It does sound as if the pump is working well enough for you to deliver water. But if you are only drawing from the top 25 ft. or so of a deep well and you chlorinate the well using normal means, it may be difficult to remove the chlorinated water as circulation and mixing of chlorine between the bottom 440 ft and the to 25 ft.of water (IF the water column in your well is really of that depth) will be virtually nil.

Search InspectApedia.com for WELL STATIC HEAD to read about the column of water in a well and its relation to the well bottom and ground surface.

If I were in an off grid property with a deep well I'd consider a solar-operated well pump system, and if my testing and well shocking found a water quality problem (bacteria, smell, other) that needed treatment, I'd add a treatment system.

No simple point of use water filter can handle all contaminants nor high volumes of usage that occur over time.

On 2016-04-12 by Kathy

We have a well on our off-grid property that we installed a hand pump on to get water. We must have introduced some bacteria as it is quite stinky now.

We only are at the property sporadically but would like to Shock it if possible. We have no way to adequately pump the chlorinated water out of the well and am wondering if it will eventually dissipate.

I do have a Berkley water filter that removes chlorine but am just wondering if pouring chlorine down the well without flushing it completely out would be a problem or how long we should wait before we use the water. The well is about 465' deep and we have a deep well hand pump that we use.

It takes about 13 strokes to get water and probably about 20-25 strokes for a gallon of water.

On 2017-08-25 by (mod) - how do I disinfect new plumbing work?

You could simply review the well sanitizing procedure given at WELL CHLORINATION & DISINFECTION, allowing the bleach solution to sit overnight in the water system to disinfect everything, or you could try to chlorinate the water downstream from the UV system, at a sufficient concentration and for a sufficient time.

Watch out: Beware that if you over-dose the well and then fill a water tank and water heater you may need to drain them during flushing out of the bleach soution.

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.

Chlorination won't harm the UV system.

BUT 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 2017-08-25 by (mod) - chlorine by weight?

Linda: at WELL CHLORINATION & DISINFECTION we give recommended bleach concentrations for this process.

Watch out: though. The simple "depth" of the well is not the key number, it's the height of the water column or the static head (search InspectApedia for WELL STATIC HEAD if that's not a term you know about)., Consider that your well could

be 600 feet deep but just have 30 feet of water in it.

On 2017-08-04 by Linda

How many gallons of 5% sodium hypochlorite will be used to disinfect a well 200 feet deep if the weight of the chlorine is .5 pounds?

On 2017-07-16 by Miriam we are not smelling bleach even though we poured some into the well

We have a 515 ft well. As best we can tell, the water level is 485 feet (we hit water when using a weighed string at 30 feet).

We put approx. 2 gal of household bleach into the well and let the hose at the well house run for over 30 minutes. Still no bleach smell.

Our water pH is between 7 & 7.4. Why can't we smell bleach in the hose yet? Is the pH too high or did we just not put in enough bleach?

We used the amount that was recommended by the University of Tennessee extension office.

On 2017-05-11 5 by (mod) - plumber bleached our well due to a bad taste in the water, now we can't get rid of the bleach smell

Warren:

You may need to drain your water pressure tank and water heater (don't turn the heater back on until it's full of water or it may be destroyed or even dangerous), then flush the plumbing system.

But, if the plumber (stupidly in my OPINION) dropped solid chlorine tablets or pool tablets into the well it's much more difficult to flush the well until those are fully dissolved. So find out what she did.

On 2017-05-11 by Warren

A plumber bleached our well due to a bad taste in the water. Since then there is a bad bleach smell and taste and a soapy foam in the water. We have run the water for hours to clear out the bleach smell and taste, both inside the house, the cold and hot water, and outside the house through a hose.

Nothing helps. As a matter of fact, it seems to be worse after running the water. What should we do to correct the problem?

On 2017-04-27 by (mod) - are my sediment filters interfering with the chlorine?

Sue

Sediment filters should not affect dissolved disinfectant such as chlorine, but the order of placement of water treatment equipment is important.

Typically installers use first a sediment filter then an activated charcoal filter. Reducing sediment makes disinfection, such as by a UV light (downstream) more effective and more durable. Charcoal filters will remove odors and tastes including of chlorine disinfectant. They can also breed bacteria if kept too long in the system without changing.

If your filters clog quickly and are in the proper sequence, then you probably want to install a larger, higher capacity filtering system than you're presently using.

See details at WATER FILTERS, HOME USE

Also see CHLORINATORS & CHARCOAL FILTERS

On 2017-04-27 by Sue

I have very heavy iron and clay sediment, which I use a filter to remove post pressure tank.

When I have chlorinated my well in the past, I have put a fresh 10 micron filter in during the recycling process. The logic is to keep as much sediment out of my pipes and water heater tank, as the water gets stirred up and becomes quite muddy.

The first time I did this, I actually had to stop the process and change the filter, as it became so clogged no water would come from the hose bib.
The filters are simply poly and string-wound types; am I reducing chlorine by doing this?

My well is 70 foot, and chlorine seems to disclose itself fairly quickly. I also run off the pressure tank after everything is back to normal, until it runs clear again.
What are your thoughts on this? Am I doing this right, or wasting a filter or two?

On 2017-01-18 by (mod) - Typical fee for paying a water treatment or well company to sanitize your well

Handy and John:

Typical fee for paying a water treatment or well company to sanitize your well is $80. to $200. U.S.D. - depending on where you live, well depth, ease of access, and other variables.

On 2017-01-17 by johnthorson13@gmail.com

What would it cost me to have a Well Company chlorinate my well?

On 2017-01-17 by handyjack

to have a well co.clorinat my well should cost me how much? ??

On 2017-01-17 by handyjack

handyjack, to have a well co. clorinate my well should cost me how much? What should I charge to clorinat my customers well so she can pass inspection?

On 2016-10-21 7 by (mod) - how long does well decontamination last?

Seriously: it depends - on the source of contaminants. For example: a single event such as changing out a well piping: the shock treatment may be reliable for a year or longer. But if there is a persistent contaminant source such as surface runoff leaking into a well, then the well contamination will reappear in days.

Glibly: Until your truck reaches the end of the driveway;

On 2016-10-19 by Jeff G

Once I've completed the decontaminating procedure with bleach and it was successful, how long is the treatment good for? 6 months? year?
Thanks.

On 2016-10-18 by Christina

We shocked our well, 2 gal of bleach for approximately 300 gallons of water. I think we may have over chlorinated.

I borrowed a high end Chlorimeter from work to test my water. The levels go down and have been as low as 0.30 ppm but then go back up sometimes over 2ppm after my outside hose has been off a while.

Why does the chlorine keep coming back like that? I have my hose stretched out all the back in the woods away from the well casing, I thought maybe it was just running back into the well. It's been 2 weeks now of running a hose outside almost 24/7. When is the chlorine going to go away?

On 2016-08-19 by (mod) - having trouble flushing out well after decontamination

Curious, Katie. Perhaps so much water was run out to flush the well and piping that you're pumping silt. But 10 days later I'd hope the silt would have settled out.

That leaves us thinking, as do you, iron. Have you tested tis brown water?

On 2016-08-18 by Katie

We had our well shocked approximately three weeks ago.

The testing strips confirmed no more chlorine roughly 8-10 days later but our water still has a brownish orange tint to it, which it did not have prior to shocking. Can it take more than three weeks for iron discoloration to resolve or does this indicate some other issue?

On 2016-08-06 by (mod) after chlorination our water is fizzy

I'm not sure what is the cause nor cure of the problem you describe; I'd first flush the system thoroughly, second be sure that the water softener or other treatment is in bypass as that will tell us if the problem is within a piece of equipment or in the water source.

On 2016-08-05 by Anonymous

after chlorination our water is fizzy and has a almost white film build up but no smell of bleach.

On 2016-04-08 by (mod) - shocked the well with a gallon of Clorox bleach - doesn't seem to have worked

Anon:

Shocking a well with one gallon of bleach is rather undetermined in its effect. To be effective you need the proper concentration of disinfectant in the well. When that is reached you can flush out the well and all piping 24 hours later. But you need to know how much water you're treating and put in the proper quantity of bleach.

If you used liquid bleach and are having trouble getting it flushed out it may help to drain your water tank and hot water tank.

On 2016-04-08 by Anonymous

It's been over a week Shocked well with 1 gallon Clorox bleach . Waited 3 hours ran water and outside spigots for almost an hour but never smelled the bleach. Now a week later there is still bleach smell in our water. How do I get the bleach out if my well water. It's been over screen and I can still smell it.

Question/complaint: My well ran out of water during the well-shock and flush-out procedure

you need to WARN people = re water discharge/well shocking. i ran my well out of water and made the situation WORSE.

Tell people not to run the water outside only for a half hour or so at a time!!!! NOT until Chlorox smell is gone - can take forever o get rid of Chlorox smell.... well needs to recharge. Now, listening to you folks, I have an even BIGGER problem. - M.P.

Reply:

Thank you for sending an important note of concern. We're on it.

Please see the warnings and procedures at WELL CHLORINATION & DISINFECTION and please let me know if any of that seems unclear or is missing anything.

Question: how do I get rid of chlorine in well water after shocking the well?

We shocked the well, it was 425 ft deep so we used 1 1/2 gal of bleach, it did not smell right away like it said. ran water in house for about 20 min and nothing, let set over night and then ran hose to recycle water. then we started smelling so we let it set again.

When flushing out we ran directly from where water enters home to outside plus rand faucets to clear out. Still strong chlorine, when I test it is orange when chlorine tester only has yellow.

We do get a lot of sediment from our well, ( brown Water) if used a lot. Any Idea how much longer it will be to clear out. Getting tired of having chlorine showers and smelling it all day long. - P.D., property manager, Harrisburg PA 8/27/2013

Reply:

IF (and this is not quite the case) your 425 ft. well were completely full of water and assuming it's a 6-inch casing, that's about 640 gallons of water in the well, plus additional water volume in the piping system.

According to CHLORINATION WELL SHOCKING PROCEDURE 1.5 gallons of household bleach was a stronger concentration than needed (1 gallon would treat about 500 ft. of water in a 6-inch well casing). Considering that if your well's total depth was just 425 ft. and that most likely the static head of water in that well was less than 425 feet total, the well was overdosed.

Overdosing with chlorine can indeed make for some extra trouble in flushing out the chlorine or bleach later.

Flushing out the well needs to run more than that volume, however, since you cannot by running water just draw out the static water that was treated with bleach; rather, water running into the well dilutes the bleached-water already therein;

You'll need to use water for several days to fully flush out the chlorine bleach; the exact volume and rate of flush-out also depends on the flow rate of the well.

Further, as you've run chlorinated water into a water pressure tank and water heater tank, those too need to be flushed, or simply drained and refilled - a step that can speed the flushout procedure. Try that and keep me posted.

Reader follow-up:

I believe [the chlorine concentration in our well water] is at 10ppm  

Reply:

The maximum residual disinfectant level goal (MRDLG) and also the maximum residual disinfectant level (MRDL) set by the U.S. EPA for chlorine in drinking water is

4.0 mg/L or 4 ppm or 4.0 mg/L or 4 ppm as an annual average respectively. [1]

I would - shut off water to the building, drain the water heater tank and pump pressure tank, run water outside - straight from the well via an outdoor faucet - and check the chlorine level there. That will help sort out chlorine remaining in the well water supply from chlorine that may have been left in water tanks and piping in the building.

If bleach was introduced into the well by pouring it directly into the well casing, it might help the flush-out procedure if you used a garden hose to recirculate some of the well water back to the well, using it to wash down the casing sides and center piping before continuing with the actual flush-out of the well itself.

Keep me posted; send along photos of your well equipment, tanks &c as that may permit further comment.

Citation on limits of chlorine in drinking water:

Question: shocked the well, sat 13 hours, bad water pressure now

(May 14, 2011) Martin said:

We shocked our well today, we let it set for 13 hours plus when we turned the pump back on and started to flush the system out the water pressure dropped and is not coming back up and the water flow itself has slowed down alot. We turned the faucet and the pump back off. Now what do we do? Thanks for the help.

Reply:

I SPECULATE that your well shock procedure has disclosed a second, separate problem, loss of well prime due to a leak that you had not previously noticed. As long as the well pump was left with power on, a slow leak, such as in the well piping or at a check valve, would result in water pressure dropping until the pump turned back on. But with power to the pump turned off for 13 hours, the leak may have been enough to lose pump prime.

In such cases you can usually get water pressure back by re-priming the pump, but you'll need to find and fix the leak to avoid repeating this problem, to stop wasting water and electricity by unnecessary pump cycling, and to protect the pump and pressure control switch from early failure due to well pump short cycling.

Question:

(June 9, 2011) Becky said:

How long does it take for the chlorine to get out of the system? We had our well pump replaced 2 days ago, there is a chemical smell and taste to the water, it is not getting any better over time. Should I be concerned that the taste/smell are so strong so long after? How long should I wait to get the water tested?

Reply:

After 24 hours of disinfection you should be able to flush out the chlorinated water in less than an hour, unless there are unusual conditions in the well itself.

You'd have trouble flushing out the chlorine if

- some fool threw solid chlorine tablets into the well - they'll sit on the well bottom for quite some time

- there were large water tanks or water heater tanks that need to be drained

Watch out: Yes remaining bleach after well sterilization is a concern: too-high a concentration may be unsafe to drink (boiling the water may help drive off chlorine), and doing laundry with high-chlorine water may bleach clothing that you 'd prefer to have left alone.

Question: putting chorine in a well where I see electrical wires

(Aug 21, 2011) Pat said:

I see electric wires in my well....do I still put clorene in the casing and then flush with a hose to make sure the bleach is off the wires?

Reply:

Pat if you follow the chlorox bleach dilution recommendations and wash down the casing interior and wiring by recycling water from a hose bib back into the well you should be ok.

If you see open electrical splices stop and have those fixed first.

Question: we put bleach in the well but we never smelled it - someone else was told to put 5 gallons of bleach in the well every month!

(Apr 30, 2012) Norma said:

We just inherited my mothers house. We have an artisian well and having problems with the water smelling like sulfur. We poured 5 gallons of bleach down the well, circulated it then ran it through the house. We never smelled chlorine. Do we need to use more bleach?

(Sept 4, 2012) Jill said:

Seconding Norma's question because a well water service man gave me a free bottle of dried bleach balls just small enough to fit down the tiny plug that allows you to drop bleach into my well. He said put "5" balls a month. I slightly smell bleach for a few minutes when releasing the water.

The bottle I had was knocked over by a rainstorm and absorbed rain water..I used them after they dried.

And shocked the well twice in less than two weeks. There was no smell when clearing the water.. When I read the results of other's stories I feel like I'm hardly shocking my well.. It smells horribly like surfer water and has only grown stronger after my last shock.

Reply:

Jill,

Really? with apologies for being blunt, the advice to put 5 bleach balls into a well a month sounds completely ridiculous to me.

The number of objections and reasons it's absurd is more than I can stand to write but here are a few:

the level of concentration of bleach needed to purify water depends largely on the volume of water involved - which is unknown in the case you describe, as is the amount of bleach in the little bleach balls.

Furthermore, bleaching a well once a month fails to address the level of contamination that may be present in the water on other days in the month after the bleach has dissolved and been run out of the well.

Shocking a well is a "fix" ONLY in the case of well contamination from a one time problem such as inserting non-sterile pipes into a well, or a mouse fell into the well;

if there is a persistent source, the source needs to be corrected, and if that's not possible, a properly designed full time water treatment system (typically a chlorinator combined with a filter to then remove the cholorine, odors, chemicals and other contaminants) is installed on the water system.

And if there are bacterial contaminants, there are often other contaminants too - so just treating bacteria is a risky approach to water potability.

The sulphur odor you describe may be horrible, but may not be unsanitary and is not necessarily due to bacteria. And chlorine or bleach is only helpful for low sulphur levels. If that's the problem yo uneed a treatment system to remove sulphur or H2S from your water supply. Not little bleach balls.

Norma:

The amount of bleach needed for a one time shock depends on the volume of water in the well and all the piping.

If you never smelled bleach when running water at faucets in the building I suspect your concentration was not sufficient. But a more reliable approach would be to find out the actual static head of water in the well - and dose it accordingly.

Norma if you did not put sufficient bleach into the well to reach a detectable concentration in the water then you won't smell it. The article WELL CHLORINATION & DISINFECTION explains how to determine how much bleach is needed.

See WELL CHLORINATION & DISINFECTION

Question: ok to leave bleach longer than 24 hours

(Sept 19, 2012) Ann said:

I'll be away from home for several months would it hurt to allow the bleach to stand for that length of time and finish the flushing process when I return?

Reply:

Ann,

Possibly, yes. Leaving concentrated bleach in a well for months might corrode the pump, connectors, wiring, or other components.

Question: black stains after bleaching well

(Sept 25, 2012) Teresa said:

We just shocked our well. When we started to flush it, the water looked black and is leaving rings around the toilets and dirt in the tub. Why? We used to have nice clear water, just a little bacteria. :-) It's been two days now and the water is still brownish and cloudy, did we ruin our well? Thanks!

Reply:

Teresa,

Presuming you used a recommended concentration of bleachnto sanitize a well, More likely the procedure disturbed something. Flush the wellmout thoroughly.

Question/comment: bleaching the well worked

Thanks, it finally cleared up. Water tested , no more bacteria.

Question: over-chlorinated the well

(Oct 27, 2014) Anonymous said:
Help. I may have overchlorinated my well.

Reply:

The chlorine will flush out of the well, but if you overdosed with the wrong material, such as chlorine tablets, indeed that will take some time. If the well is too deep to retrieve the solid tablets (if that's what you did) then recycling water through the well can speed the dissolution, followed by a flushout.


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