Well Shock Procedure Q & A

Bleach Disinfection of Plumbing After Plumbing Work

Our plumber poured a half gallon of undiluted Clorox into our new jet pump - did he damage it?

Our plumber poured a half gallon of undiluted Clorox into our new jet pump to sterilize it during installation. Then about a half hour later, he finally started up the pump to circulate the bleach through the system. A lot of red water and sediment came out of our faucets.

We're worried that the strong bleach may have damaged the pump. Is that possible? Thanks. On 2022-06-16 by David

by InspectApedia-911 (mod) - attempting to disinfect a water system after working on plumbing is a reasonable practice

@David,

Of course knowing nothing about your building, I can't provide an absolutely certain answer,

Attempting to disinfect a water system after working on plumbing is a reasonable practice although I'm not sure that what the plumber did is the best approach.

Nevertheless, it's not likely that what the plumber did has damaged your building plumbing nor the pump. As soon as the pump runs the bleach in the pumping chamber is being diluted with a large volume of well water.

More likely it was the installation of the new pump combined with a period of no water flowing in the pipes and then suddenly flowing again that stirred and displayed sediment from your piping system.

Watch out: however disinfecting the pump and house water pipes with an arbitrary volume of bleach gives NO assurance that your building water pipes were adequately disinfected.

To disinfect a water pipe effectively you'd need to have an adequately strong concentration of bleach-water that sits in the pipe for an adequate length of time.

I wouldn't panic about this, but if you're worried about the sanitation of your new plumbing pipes you might want to consider a more careful disinfection step for pipes, water tank, water heater, etc.

You'll see how that's calculated based on the volume of water involved at WELL CHLORINATION SHOCKING PROCEDURE

Also see

• Pfeil, Adel L., Sulfur Water Control (Rotten Egg Odor in Home Water Supplies) (1990) (Website) School of Agriculture, Purdue University Cooperative Extension Service, West Lafayette Indiana, with US Department of Agriculture cooperating. - Local backup copy saved as Sulfur-odor-in-water-Pfeil.pdf

Using Hydrogen Peroxide to Disinfect a Water Well ?

I plan on Shocking our well with hydrogen peroxide in the form of NutraSul. Is that safe?

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 ( which is 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 2017-10-10 by Frances Donovan -

by (mod) - Don't rely on hydrogen peroxide for well disinfection - it's intended for sulfur odors.

So yes, hydrogen peroxide solution is recommended by expert sources for treating sulfur odors or water discoloration, NOT for water disinfection.

In contrast, household bleach or chlorine is recommended by expert sources for use in well disinfection but NOT for treating sufur odors.

Watch out: As we report in the article SULPHUR ODORS in WATER, there are of course other sources of sulphur odors such as bacterial contamination, so it might make sense to be sure you know the cause of a water odor problem before applying a cure.

Bottom line:

Watch out: Neutra-Sol (7% hydrogen peroxide solution per ANSI / NSF Standard 60) is used for treating sulfur odors or smells in water, NOT for well disinfection.

Neutra Sul is manufactured by Summit Brands but you may find as we did that searching for product information results in lists of distributors of the product, but manufacturer's contact information is a bit tougher to find unless you look at the product's SDS Sheet.

• Neutra-Sul SDS (Safety Data Sheet) [PDF] (at a Canadian Shopify website)
• Neutra-Sul MAX Safety Data Sheet [PDF] (at a Canadian Shopify website)
• Here are all of the Pro Products Safety Data Sheets (Pro Products website) including other versions of this product
• Also see our list of the sources of sulfur odors in water found at WATER ODORS, CAUSE CURE 

If I put Cl₂ in my well to disinfect it, 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 2017-12-21 by Joe -

Reply by (mod) - No problem: Cl₂ or Chlorine bleach at normal household concentration 5-9% is what's used to disinfect a water well

Using plain unscented bleach to disinfect your well is the right disinfectant.

While the NutraSul folks say it's wrong to use chlorine to remove sulfur from a water well, a more neutral expert source such as we'll cite below will tell you that there's no conflict and that in fact household bleach - chlorine bleach - is effective in removing low to moderate levels of sulfur or hydrogen sulfide in drinking water.

Research on Using Chlorine to Treat Hydrogen Sulfide (rotten egg smell) in drinking water

• Clark, G. Douglas, ed., The Indiana Water Resource, Availability, Uses and Needs, Indiana Department of Natural Resources, Indianapolis, 1980, p. 86.
• Pfeil, Adel L., Sulfur Water Control (Rotten Egg Odor in Home Water Supplies) (1990) (Website) School of Agriculture, Purdue University Cooperative Extension Service, West Lafayette Indiana, with US Department of Agriculture cooperating. - Local backup copy saved as Sulfur-odor-in-water-Pfeil.pdf
• "Water Treatment Fundamentals", l983, Water Quality Association Educational Services
  

Well Disinfection vs UV Light vs Persistent Contaminant Source Q&A

Well water had coliform bacteria; how do I disinfect new plumbing work? Shock the well?

I recently bought a home, well failed for total coliform. There was no e coli or fecal. The sellers are 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 2017-08-24 by mongo

by (mod) - multiple health warnings

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 solution.

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.

Watch out: aAlso most UV lights come with instructions recommending an annual replacement of the bulb.

Watch out: aAlso, 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.

Does my well need regular chlorine treatments if it fails a bacteria test?

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 2017-04-11 by Chris

by (mod) - your bleach quantity may be mistaken and no, you should not need regular well disinfections

Chris,

I don't think anyone is suggesting that regular "chloronation" 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.

Watch out: if the well water is persistently not potable after disinfecting it, AND PROVIDED that you're using the proper quantity and procedure for well disinfection, then shocking it won't fix the problem and you'd need a water treatment and disinfection system in your home.

Chris follows up with advice from Alaska DEC on water purification

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!

by (mod) - Alaska water well disinfection

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.

Watch out: Disinfecting water addresses specifically bacterial contaminants only. If other contaminants are present other treatment or filtration will be needed.

Watch out: If your next well test result fails a bacteria test, that may simply reflect that you didn't use the proper bleach quantity or didn't let it sit in the well and in the house piping long enough. - Daniel Friedman

by Chris - results of well shocking: positive for T coliform

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.

Sediment in the Well vs Well Disinfection Q&A

Do Sediment-Clogged Filters Interfere with Well Disinfection Procedure?

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 2017-04-27 by Sue

Advice by (mod) - no but high sediment levels in well water are a concern for the disinfection procedure

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

Followup by SUE

Thanks!
Don't have an odor or taste problem, just yellowing of white clothes and tubs. There wasn't a problem when I had a jet pump,

but when the submersible was installed, it seemed to pull up a lot more TDS. I have only had to disinfect twice, once after incompetent plumbers installed said pump, then again, as incompetent ME had not read this website, and was too timid to add enough bleach!

My set up is: Pump, pressure tank, sediment filter, acid neutralizer then softener. So far, so good. I am waiting for the ambient air in my house to warm up a bit before I do a bacteria screening, which I perform every year.

by (mod) - cause of yellowing of white clothes and tubs

Did you check the iron level of the water? That can cause the yellowing of clothes and tubs you cite.

Research on Impact of Sediment on Well Disinfection

• Basso, Odile, Jean‐François Lascourrèges, Marc Jarry, and Michel Magot. "The effect of cleaning and disinfecting the sampling well on the microbial communities of deep subsurface water samples." Environmental Microbiology 7, no. 1 (2005): 13-21.
• Léziart, Tangui, Pierre-Marie Dutheil de la Rochere, Ryan Cheswick, Peter Jarvis, and Andreas Nocker. "Effect of turbidity on water disinfection by chlorination with the emphasis on humic acids and chalk." (Taylor & Francis website)  Environmental technology 40, no. 13 (2019): 1734-1743.
  Abstract:
  Chlorine is globally the most widely used chemical for water disinfection.
  
  Whereas disinfection efficiency is well known to depend on water pH and temperature, the effect of turbidity is less well studied. Although turbidity is measured online in most drinking water works and most countries where regulations exist have set limits of <1 NTU for water leaving the works, the composition of turbidity is typically unknown.
  
  Given the heterogeneous nature of substances contributing to turbidity, the aim of this work was to study the effect of selected compounds on chlorination efficacy.
  
  The effect of humic acids and chalk on the inactivation of the indicator bacteria Escherichia coli and Enterococcus faecalis was assessed at neutral pH at different turbidity levels using both plate counting and flow cytometry in combination with membrane integrity staining. For humic acids, a turbidity of 1 NTU (corresponding to 2 mg L−1) was identified as a critical threshold, which when exceeded was found to have a negative impact on chlorine disinfection.
  
  Chalk, on the other hand, had no measurable impact up to 5 NTU.
  
  The observation applied to both bacterial species with identical conclusions from the two diagnostic methods. Results corroborate that different turbidity causing substances affect chlorination efficiency to very different extents with chlorine demand by organic material probably being the most important determinant.
  
  In the case of turbidities >1 NTU, turbidity measurement benefits from the consideration of the organic content as mere NTU values do not allow predicting an impact on chlorination efficiency.
• Reiber, Steve, and Glenn Dostal. "Well water disinfection sparks surprises (Wiley online library) Opflow 26, no. 3 (2000): 1-14.
  
  Abstract:
  The installation of chlorination at a mid-size Midwestern water system set in motion a series of events that shocked managers and raised a perplexing chemical question. The situation, ironically, also may have briefly threatened the health of the public they were working diligently to serve.
• Osborne, Erika, Madison Haddix, and Emily Garner. "Impact of hydraulic and physicochemical factors on spatiotemporal variations of particle-associated bacteria in a drinking water distribution system." Frontiers in Water 4 (2022): 959618.
• Templeton, Michael R., Robert C. Andrews, and Ron Hofmann. "Particle-associated viruses in water: impacts on disinfection processes. (Taylor & Francis website) Critical Reviews in Environmental Science and Technology 38, no. 3 (2008): 137-164.
  
  Abstract: Studies have shown that viruses are frequently attached onto or enmeshed within suspended particles in natural water and wastewater and that this viral–particle association can impede disinfection processes in some circumstances.
  
  This article summarizes the current state of knowledge of the occurrence of particle-associated viruses in the aquatic environment and the reported subsequent impacts on disinfection processes. The intention is that this article will help guide future research and aid regulators attempting to address the disinfection of particle-laden waters.
• Wu, Binbin, Yanling Zhang, Huachang Hong, Mei Hu, Hailong Liu, Xi Chen, and Yan Liang. "Hydrophobic organic compounds in drinking water reservoirs: Toxic effects of chlorination and protective effects of dietary antioxidants against disinfection by-products." Water Research 166 (2019): 115041.
• Zhu, Ni, Kris Mapili, Haniyyah Majeed, Amy Pruden, and Marc A. Edwards. "Sediment and biofilm affect disinfectant decay rates during long-term operation of simulated reclaimed water distribution systems." Environmental Science: Water Research & Technology 6, no. 6 (2020): 1615-1626.
  
  Discusses the effects of accumulated sediment on disinfection efforts for water distribution systems.

Running out of Water During or After a Well Disinfection Procedure

No water from the well after it was shocked

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. (May 14, 2011) Martin

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, as we explain at WATER PUMP PRIMING PROCEDURE

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.

The probable repair needed is a new foot valve - see WELL PIPING FOOT VALVES