Well Chlorination Q&A on Using Bleach & Artesian Well Disinfection

How Much Disinfectant is Needed to Shock a Well?

Tip: See WELL CHLORINATION & DISINFECTION

I never smelled chlorine after putting a gallon into our well: do I need more disinfectant?

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? On 2017-12-08 by Rees

by (mod) - never smelled nor found chlorine after we shocked the well

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

Watch out: if you don't use enough disinfectant the well is not sanitary

Watch out: if you use too much disinfectant it can be difficult to flush the disinfectant, bleach, etc. out of the water supply

by Rees

Thanks, Danjoe. So, not knowing how deep the well is, I should just dump a lot more chlorine?

Answer by (mod) - measure the well depth & compute the bleach dose

Rees you will need to measure the actual static head of water in the well and use that plus the well diameter to calculate the volume of water in the well and then use our bleach table in the article I cited earlier to see how much bleach to use.

See just how to do this in these articles and procedures

WELL DEPTH, HOW TO MEASURE

STATIC HEAD DEFINITION

WELL WATER VOLUME CALCULATION

Doing anything else is arbitrary and unsafe. - Daniel Friedman

Bleach Quantity to Shock a Well: Not Enough?

I put in bleach but never smelled at indoor fixtures

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? Brian

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.

How much disinfectant to use in a 200ft deep well?

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 2017-08-04 by Linda

by (mod) - chlorine by weight? well depth isn't all you need to know

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.

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!

We just inherited my mothers house. We have an artesian 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? (Apr 30, 2012) Norma

And from another InspectApedia reader:

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. (Sept 4, 2012) Jill

Reply: bleach to get rid of sulfur smells in water?

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 chlorine, 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 sulfur 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 sulfur levels. If that's the problem you need a treatment system to remove sulphur or hydrogen sulfide 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

Ran a gallon of pool shock into the well, water now is orange and black.

Chlorinated well 1 gallon. When run hot water in tub upstairs it’s light orange. The tub downstairs is grey black looking. I ran all faucets about 10 minutes after 24 he. Setting w-pool shock. On 2021-08-22 by Deb

by inspectapedia.com.moderator - Watch out: wrong chemical and amount: you have not successfully flushed the well

@Deb,

Sounds like you have not successfully flushed the well.

And why on earth are you using pool shock in a well?

And how did you compute how much disinfectant to use? 1 Gallon sounds arbitrary.

See procedures and proper type and amount of disinfectant to use in a well at

WELL CHLORINATION & DISINFECTION - topic home -

and let me know what questions remain

How Long to Leave Disinfectant in the Well during a Well Shock Procedure

Is it OK to leave bleach longer than 24 hours

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? (Sept 19, 2012) Ann

Reply:

Ann,

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

Disinfecting an Artesian Well Q&A

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

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? (Jan 31, 2014) Ken

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.

See our InspectApedia article

ARTESIAN WELLS, WELL SPOOLS

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.

Watch out: considering that there is constantly new water flowing rapidly into your artesian well and even excess water flowing out of it to an acceptable disposal location, it's most important that you have the water tested for potability.

If the water source is not safe to drink it will need treatment with an appropriate disinfection or other water treatment equipment that are typically installed indoors at your water pressure tank.

When to Disinfect the Well - Timing Q&A

Well Disinfection Procedure After New Pump & Pipes Installed - when to shock the well

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 (Mar 9, 2014) Kristi

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: New pump and pipes in well, pumped until clear, then installer used chlorine tablets in the well

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; your well has apparently not run dry so that's not the issue.

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.