FAQs on how to shock or disinfect a drinking water well or fixing troubles if shocking doesn't work or leaves bleach or chlorine odors. Set no. 2.

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

FAQs on how to sanitize a well, posted originally

at WELL CHLORINATION & DISINFECTION - be sure to see the procedures and advice given there.

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: how to get bleach into the well

(Mar 30, 2013) willy said:

i have two water lines going into my pump. i can not remove the casing. it has a concrete floor with a metal lid and is bolted down, very rusty.

can i remove one of the lines and pour the bleach down into the well. will this help with cloudiness coming out of the Faust, or should i replace the water lines from the pump house to the main house?

Reply:

Willy,

If you can get enough bleach to circulate through the system - based on the amount of water in the static head of the well) it might work.

Unfortunately when pump parts are badly rusted, messing with it often leads to a complete replacement.

Often a plumber can cut into a pipe to provide fittings needed to insert bleach when well shocking is needed and usual openings are stuck or not accessible.

Reader follow-up:

(Apr 2, 2013) Anonymous said:

thank you . i did some more investigation and my neighbor asked me if i have to prime my pump often. i told him that i had only once since i lived here.

he mentioned that my pump pushes 1 parts water back into the well and pumps out 3 parts. I have never heard of this type before and now i need to know if i should keep this type of system or have a new well drilled and get a submerse pump. your feed back would be greatly appreciated in this matter. as i'm new to living the country life. never needed to worry about water in the big city. thx Willy

Question: My well fills up to the cap when the pumps not running.

(Jan 31, 2014) Ken said:

My well fills up to the cap when the pumps not running. When the pumps running, water drops down about 6 feet below the cap. Will pouring Clorox down the shaft still mix with the water to disinfect?

Reply:

Ken,

First-off it sounds as if you have an artesian well that lacks a proper well seal near the casing top.

If you follow well disinfection best practices you will connect a garden hose to an outdoor hose bib and re-cycle the disinfectant solution from the well casing, through the water piping system, back to the well head, where you use the hose to spray down the well casing that extends above the top of the water level itself, disinfecting and washing down the piping, (water-protected) wiring, and casing sides.

Watch out though: make sure your disinfectant solution is of adequate strength; and you may find that running disinfectant solution through a water pressure tank or water heater tank as well as through the well casing will mean that extra water quantity will be needed later to flush out the disinfectant solution from the whole system.

Ken, regarding your observation that when the pump is not running your well water level rises right up to the well cap, if your well piping exits the well not out of the well cap but out of the casing side through a pitless adapter - as would be needed in freezing climates - allowing well water to rise above the pitless adapter risks a well sanitation hazard.

Search InspectApedia for the article titled

Flowing Artesian Wells Construction, Troubleshooting, Repairs

for details about the need for installing a well spool

About mixing the bleach into the well, if you are not going to make up a disinfectant mix with water in a mixing tank for injection into the well, a second approach should help:

connect a garden hose and recirculate the disinfected water from well through piping and pump through a new clean garden hose connected to an outside hose bib (sill cock) back to the well casing, washing down casing sides in the process. Experts use a pipe on hose end to also make sure water is injected at depths below well water top surface

Question: Importance of pH adjustment in well water when sanitizing a well

1/31/2014 Re-posting Mark's comment without the hyperlink (links in comments are prohibited by the software in order to protect against malware)

Actually, one of the best places for bacteria to live is in the static to draw-down area.

I should have also stated that slime-forming bacteria can hide the real nasty stuff (coliform and e-coli). And the slime can inhabit all down the casing, the screens and out in to the aquifer. According to Well folks it can be necessary to brush out a well in order to achieve a good kill on the bacteria.

Again, pH IS EXTREMELY IMPORTANT! Here, read this (from the great water folks up in Canada):

"When Standard Water Well Chlorination Procedures are Ineffective - Fact Sheet developed for Well Drillers, Health Authority Staff and others involved in well recovery efforts after a flood " - British Columbia Ministry of Environment

In general, they adjust water in a tank to a pH of 4.5 and THEN add chlorine. I wasn't aware of this procedure until after I mixed up my solution. Now that I have an actual personal experience in this I think that I can comment on it... I mixed up a 200ppm sodium hypochlorite solution (8.25% Clorox) in 275 gallons of pH neutral water (my spring water is nearly dead-on, 6.8 - 7.0 pH).

I had ASSUMED, based on all the casual experts comments (in addition to information from various water publications [people that actually should be responsible]), that I shouldn't be too far off pH-wise- WRONG! I'm over 8.4 pH!

If you read WELL CHLORINATION & DISINFECTION you'll find that having a pH value that is much beyond neutral won't be effective as a biocidal. All of this should tell folks why they have difficulties really getting the job done and then have to end up shelling out a lot of money to pay a professional.

I am now trying to adjust the pH down... (don't have a lot of time before I lose the chlorine efficacy). Yes, there IS a reason why the good professional Well folks should earn what they do.

Reply:

Thanks for important comments, Mark. I have added your comment and information about well shocking and disinfection following area flooding in the article series given at the end of this page.
Daniel

Question: nervous about having the well piping & pump pulled out of the well

(Mar 9, 2014) Kristi said:

We are having our drilled private well pump "pulled" tomorrow and I am extremely nervous. Getting to this point has been a long process and I have learned more about water, plumbing, and water testing that I even want to know- However, I do not feel prepared. I have 3 small children and want to be sure we are safe.

We have had 9+ years of "water problems" (you name it) at our home. Our goal was to find/fix problems without having to open the well up. Tomorrow, My husband, an electrician, a water specialist, and the pump installer will be here together during the process.

We have had so many things go wrong that I have lost faith in "professionals" doing quality, honest work. I also acknowledge that many solutions have been attempted without success to no fault of the persons advice. To make an extremely long, exhausting story short we have corrosion problems and the last test is to open the well and look for "stray voltage" within the pump.

Since the pump is now 10 years old, the plan is to probably replace it with a "new" one (better be!) I am looking for any last minute advice you may have prior to "shocking the well" to prepare.

FYI- money have never been the issue- I want it done correctly, thoroughly and safely. I do not believe in short cuts. Do you ALWAYS recommend disinfecting an open well? I want to get some water samples directly from well. What would you recommend testing for? Do you have maybe a Top 10 checklist of most important things to remember when opening your well up? Thank you so much for your time. KH

Reply:

Kristi

The process of drilling the well and inserting pump and piping are of necessity not sanitary; the well pipe is not delivered in a sterile condition, not to mention its handling during installation;

It is normal procedure to sterilize a new well and it is normal procedure to shock the well after piping has been pulled and replaced or repaired.

You should have the water tested including for corrosivity as extra measures may be needed.

You should ask the driller to check the condition of the well casing, pitless adapter, foot valve, pump wiring, and the security and sanitary condition of seals such as at the pitless adapter and well cap.

Reader follow-up: chlorine tablet troubles

Been a long day... New well pump, new pressure tank.... no solutions, more questions. Lots of well casing bits all over inside well pipe, etc. However, my specific question and concern is: What is the chance we could "run our well dry". The professional pump installer we had here today put a new pump in, pumped water out of pipe until clear, then used chlorine tablets.

We purposely do not have the chlorinated water circulating into the house.

It come in the basement only to the point of running to a very nearby outside spigot. The spigot is fully open, with a hose attached running full flow water to woods in backyard. My husband says he is doing as the pump installer recommended. The chlorine did not sit at all.

The water has been running immediately following the closing of the well cap, and he was told to keep it running... maybe 24 hours, until the chlorine spell is gone. Does that seem right?

The pump in continually running, with the flow maxed out... since 3pm this afternoon. FYI- we are not doing this due to high bacteria levels.

We are trying to find source of corrosion... trust me, it's been a baffling unfortunate experience. Lots of experienced people scratching their heads.

Reply:

Chlorine tablets are a difficult way to treat a well - difficult to wash down casing sides, difficult to distribute throughout the well, and difficult to flush from the well; And not pertinent to determining a corrosion source. But it is correct to shock a well after removing and replacing pump and piping.

If you test the water for corrosivity and find that its corrosivity index is LOW then the problem is not the water source.

If then you are finding abnormal corrosive conditions you'd look for an electrical grounding problem or a metals-mixing galvanic corrosion problem, or a corrosive soils problem around the well casing or piping.

Question: lost water then water color is yellow, is running the yellow water for 5 minutes sufficient to make it safe?

(June 18, 2014) Anonymous said:

I live in a development with 33 other homes sharing the same well. Last week we lost power for 4 hours but when it came back on we had no water. We were without water for 14 hours. The water is yellow and I was told to run my water for 5 minutes and it should clear up. I did that, but it did not help.

So,my question is as follows
"By me running my water for 5 minutes how will it help when we all share the same well?"

Reply:

Anon, I think the person giving the advice you cite figures that when a water supply stops flowing, sits, then re-starts, sometimes the process stirs up debris in the system tanks, ping, or in the well itself. If the debris is just a temporary anomaly it should be flushed out by use. More tha 5 minutes may be needed.

On a community water system of your size, regular water quality testing is required. You might ask to see the results.

Certainly if flushing the system of yellow water for 5 minutes leaves you still seeing yellow water then flushing was not a cure for anything.

Question: frequent clogging of water filter - raise up the foot valve or pump?

(June 29, 2014) Anonymous said:

my well filter is changed every month and it is rust colored. my question is if I pull the pump up two or three feet will this help my problem?

Reply:

Anon,

I suspect not - you are probably describing rust and fine sediment in the water. But sure, I'd give it a try on the chance that there is a thick deposit of fine sediment at well bottom. It's a comparatively low-cost experiment. If that doesn't work you will want to install a larger capacity filter system.

Raising a pump or foot valve would more likely help if the water pick up was indeed close to the well bottom (say a foot) and if you were seeing larger sediment.

Question: I put in bleach but never smelled at indoor fixtures

(5 hours ago) Brian said:

I put a gallon of bleach into the well and went into the house and ran the water for an hour or more and never smelled bleach. What happened?

Reply:

Brian most likely you never put in enough bleach to reach a detectable concentration in the well water. Read WELL CHLORINATION & DISINFECTION where we discuss the quantity needed - it depends on how much water is in the well and in building piping, tanks, etc.

Question: will bleach-smelling water pass a bacteria test

(July 21, 2014) magnolia said:

Can the water test pass inspection if there is still STRONG bleach odor after shocking?

Reply:

Magnolia

Oh yes your water test will probably pass a bacterial test after shocking and while a strong bleach odor remains, but the test will be improper, possibly illegal or deceptive and may risk the health of future occupants.

A proper re-test flushes all bleach from the system and waits several days, preferably a week so that if bacterial contamination remains it can be detected.

If I were collecting a water test sample at a building where I smelled or detected chlorine in the test water (I use a test strip for that purpose) I would not complete the test as it would be improper.

...

Continue reading at WELL CHLORINATION & DISINFECTION or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see WELL DISINFECTION FAQs-3 - more-recent questions and answers about solving problems when or after shocking a well

Or see these

Recommended Articles

• WATER TREATMENT EQUIPMENT DISINFECTION
• FLOOD CONTAMINATED WELL RESTORE & PROTECT
• WATER WELL SAFETY & SANITATION, 6 STEPS-EPA
• WELL CHLORINATION & DISINFECTION
• WELL CLEANING PROCEDURES
• WELL CLEANING & RESTORATION by GLYCOLIC ACID
• WELL DISINFECTANT CHOICES
• WELL DISINFECTANT pH ADJUSTMENT
• WELL DISINFECTION PROCEDURE, POST FLOODING
• WELL CONSTRUCTION INFORMATION SOURCES

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WELL DISINFECTION FAQs-2 at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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INDEX to RELATED ARTICLES: ARTICLE INDEX to WATER TREATMENT SYSTEMS

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