WATER TESTING GUIDE
WATER TESTING ADVICE WATER TESTS, WATER TREATMENTS
Common Water Tests for Bacteria
PA - Coliform Bacteria Test
M.F.T. - Coliform Bacteria Test
MPN - Coliform Bacteria Test
Interpreting Other Water Test Results
What to Do About Failed Water Tests
Water Test Procedure Errors
Detecting Water Test Cheating
Interpreting the Level of Bacteria
When & How to Shock or Chlorinate a Well
Acting on Unsatisfactory or Contaminated Water
Wells that Pass a Second Water Test
Wells that Fail a Second Water Test
When to re-test a well
Odors in Water, Types, Causes
Treatment for Contamination, Hardness, Odors, etc
Pros/Cons of Types of Water Treatment Equipment
Water Filters
UV - Ultraviolet light
Reverse Osmosis
Chlorinators with Charcoal Filters
Odor & Taste Contaminants
Water Softeners
Sediment & Iron Filters
Sulphur odor filters
Water Treatment Chemical Safety
FHA WATER TESTS REQUIRED
WELLS CISTERNS & SPRINGS
WELL CHLORINATION SHOCKING PROCEDURE
Chlorine in Wells - Safety Warnings
Well Chlorination Procedure Details
More Information
InspectAPedia ® Home & Site Map
Air Conditioning
InspectAPedia Bookstore
Electrical
Environment
Exteriors
Heating
Home Inspection
Insulate Ventilate
Interiors
Mold Inspect/Test
Plumbing Water Septic
Roofing
Structure
Accuracy & Bias Pledge
Contact Us
|
Well Chlorination Procedure: when and how to shock a drinking water well
WaterAPedia ©
|
- When to shock or chlorinate a drinking water well
- What is the procedure to shock or chlorinate a well?
- How much bleach or hypochlorite do you use to shock a well?
- When should well water be re-tested after shocking the well?
Our site offers impartial, unbiased advice without conflicts of interest.
We will block advertisements which we discover or readers inform us are associated with bad business practices,
false-advertising, or junk science. Our contact info is at
inspect-ny.com/appointment.htm.
This is a description of the well shocking procedure using household bleach to sterilize well water and water equipment. The purpose of shock disinfection of a well system is to destroy bacterial contamination present in the well system at
the time of disinfection and is not intended to kill bacteria that might be introduced at a later time. Page top sketch of deep and shallow wells courtesy of Carson Dunlop.
This website explains many common water contamination tests for bacteria and other contaminants in water samples. We describe what to do about contaminated water, listing common corrective measures when water test results are
unsatisfactory. We include water testing and water correction measures warnings for home owners and especially for home buyers when certain conditions are encountered, with advice about what to do when these circumstances are encountered.
Various treatment methods for contaminated water are reviewed and the pros and cons of each are discussed.
© 2008 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.
When and How to Shock or Chlorinate a Well - Procedure for Shocking a Well to (temporarily or maybe longer) "Correct" Bacterial Contamination in Well Water
This information is from the Dutchess County Health Department's environmental laboratory but you'll find that it is consistent with the well shocking or well chlorination procedures recommended by most health authorities.
The purpose of shock disinfection of a well system is to destroy bacterial contamination present in the well system at
the time of disinfection and is not intended to kill bacteria that might be introduced at a later time.
Our photo shows an owner who has lifted the loose, poorly-sealed well piping and cap right off of the steel well casing. This well needed repairs and it needed to be sterilized using the well chlorination procedure we discuss here.
Therefore it is vital that the well be constructed so that no new contamination may enter the well following completion of the
shock disinfection. In order to achieve a satisfactory disinfection of the system, the bacteria must be brought in contact with a chlorine solution of sufficient strength and remain in contact with that solution for a sufficient time to achieve a complete kill of all bacteria and other microorganisms.
Chlorine in Wells - Safety Warnings
When working with chlorine, people should be in a well-ventilated place. The powder or strong liquid should not come in contact with skin or clothing. Solutions are best handled in wood or crockery containers because metals are corroded by strong chlorine solutions.
Details of the Well Chlorination Procedure - Exactly How to Shock a Well, Where to Put Chlorine, How Much Chlorine to Use to Shock the Well
|
If drinking water has been tested and has not passed standards for safe drinking, or any time the building water supply system has been opened for repairs (such as replacing a submersible well pump or a jet pump foot valve), the well should be disinfected following these procedures, and should be re-tested as described below.
Our photo shows a standard modern 6" steel well casing - it's easy to spot at a property.
If you don't know where the well is located you'll have to find it before this well chlorination procedure can be best performed. See WELLS CISTERNS & SPRINGS for articles that describe different types of water wells, what they look like, where they're found, and their operating characteristics.
It's possible to get chlorine into the well by sending it through the building piping and pump but that step won't sterilize the interior and sides of the well casing - so the procedure below is a better one. |
- Pour Clorox™ Bleach (or an equivalent brand of household bleach) or hypochlorite granules down into the well. Some people use swimming pool chlorine tablets which have the advantage that they sink to and sterilize water at the well bottom, and the disadvantage that it takes longer to flush out the chlorine.
- How much bleach to use when shocking a well: Health department officials can give more precise guidance about the amount of disinfectant needed based on the depth of the well. Common guidelines:
- Well depth 100' - 3 cups Clorox or 2 oz. of granules.
- Well depth 200' - 6 cups Clorox or 4 oz. of granules.
- Well depth 300' - 9 cups Clorox or 6 oz. of granules.
- Well depth 400' - 12 cups Clorox or 9 oz. of granules.
- Well depth 500' - 1 gallon Clorox or 12 oz. of granules.
- NOTE to be accurate in reaching the necessary concentration of chlorine in your well, treat the "depths" listed above as if they were the height of the actual column of water in your well (assuming a standard casing which is 1.5 gallons per foot of height). So if your well is 400 feet deep, but if 100 feet of it is air, your water depth is actually 300 ft.
- Introduce the chlorine solution into the top of the well. Remove the cap at the upper terminal of the well casing and pour the chlorine solution down the inside of the casing. If the well casing terminates through the floor of a pump house, then the casing is required to have a well seal at the upper terminal [i.e. at the top of the casing]. This well seal can be loosened and the chlorine solution introduced into the well at that point. In a large diameter well [such as a public supply company's well], the chlorine solution should be poured or splashed around the wall of the well so that all inside surfaces of the well are brought into contact with the strong chlorine solution.
- Using a garden hose, spray water down into the well pipe to wash the chlorine solution down to the bottom of the well. Ten gallons of water should be enough. [More won't hurt nor risk running the well dry since you're recycling the well water through the plumbing and back to the well.]
- Turn on all cold water household taps until you can smell the Clorox coming out of the faucet farthest from the well.
- Turn off the water and do not use it for 8 to 24 hours. Seal the top of the well. Do not run laundry with this chlorinated water or it may bleach clothing unexpectedly.
- At the end of the standing period, operate the well pump (run the water) water until you can no longer smell the Clorox. Do not run Clorox into the septic system - run water outside through an outside faucet or hose. There should be a hose connection at the at the bottom of the water tank. When you no longer smell chlorine at the hose draining the water tank, close off the drain and open all faucets in the house to flush out house piping for fifteen minutes or until you no longer smell or taste chlorine [whichever is longer].
- 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 retest the more valid will be the results. I elaborate on this point at "When to re-test your well water" below.
Technical Reviewers & References
Particular thanks are due to experts and also consumers who read these articles and suggest corrections, changes, and additions to
the material. Content suggestions, technical corrections and content critique are invited for any of the content at our website.
- Daniel Friedman - principal author/editor of the InspectAPedia TM Website
- Thanks to Alan Carson and Bob Dunlop, Carson Dunlop, Associates, Toronto, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education, publications, report writing materials, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
- Critique, contributions wanted: Contact Us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution.
Use just below or links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.
WATER TESTING GUIDE
WATER TESTING ADVICE
WATER TESTS, WATER TREATMENTS
Common Water Tests for Bacteria
PA - Coliform Bacteria Test
M.F.T. - Coliform Bacteria Test
MPN - Coliform Bacteria Test
Interpreting Other Water Test Results
What to Do About Failed Water Tests
Water Test Procedure Errors
Detecting Water Test Cheating
Interpreting the Level of Bacteria
When & How to Shock or Chlorinate a Well
Chlorine in Wells - Safety Warnings
Well Chlorination Procedure Details
Acting on Unsatisfactory or Contaminated Water
Wells that Pass a Second Water Test
Wells that Fail a Second Water Test
When to re-test a well
Odors in Water, Types, Causes
Treatment for Contamination, Hardness, Odors, etc
Pros/Cons of Types of Water Treatment Equipment
Water Filters
UV - Ultraviolet light
Reverse Osmosis
Chlorinators with Charcoal Filters
Odor & Taste Contaminants
Water Softeners
Sediment & Iron Filters
Sulphur odor filters
Water Treatment Chemical Safety
FHA WATER TESTS REQUIRED
WELLS CISTERNS & SPRINGS
More expert information on this topic |
WATER TESTING GUIDE
WATER TESTING ADVICE WATER TESTS, WATER TREATMENTS
Common Water Tests for Bacteria
PA - Coliform Bacteria Test
M.F.T. - Coliform Bacteria Test
MPN - Coliform Bacteria Test
Interpreting Other Water Test Results
What to Do About Failed Water Tests
Water Test Procedure Errors
Detecting Water Test Cheating
Interpreting the Level of Bacteria
When & How to Shock or Chlorinate a Well
Chlorine in Wells - Safety Warnings
Well Chlorination Procedure Details
Acting on Unsatisfactory or Contaminated Water
Wells that Pass a Second Water Test
Wells that Fail a Second Water Test
When to re-test a well
Odors in Water, Types, Causes
Treatment for Contamination, Hardness, Odors, etc
Pros/Cons of Types of Water Treatment Equipment
Water Filters
UV - Ultraviolet light
Reverse Osmosis
Chlorinators with Charcoal Filters
Odor & Taste Contaminants
Water Softeners
Sediment & Iron Filters
Sulphur odor filters
Water Treatment Chemical Safety
WATER TESTING GUIDE
WATER TESTING ADVICE
FHA WATER TESTS REQUIRED
WELLS CISTERNS & SPRINGS
More Information
InspectAPedia ® Home & Site Map
Air Conditioning
InspectAPedia Bookstore
Electrical
Environment
Exteriors
Heating
Home Inspection
Insulate Ventilate
Interiors
Mold Inspect/Test
Plumbing Water Septic
Roofing
Structure
Accuracy & Bias Pledge
Contact Us
|
More Information on Water Testing, Water Contamination, & Building Diagnostic Inspections and Repairs
- Cheating on water tests: Testing Water for Real Estate Transactions - make sure your water test is valid
- Drinking Water Testing Advice for home buyers home owners home inspectors
- Interpreting Drinking Water Test Results and Correcting Unsatisfactory Water
- Drinking Water Contaminant Levels - Maximum Allowed
- Drinking Water Contamination and Pollution How to Detect, Test, Correct, and Prevent Well Water Contamination - US EPA - Groundwater
- Lead Contamination in Drinking Water: Testing & Correction - Advice (This Article)
- Lead Testing & Correcting Contamination from Lead Water Supply Lines/Entry Mains - Lead Pipe Problems/Advice
- Extreme Lead Poisoning Symptoms Suggested by Feb. 2006 NY Times Article on Kosovo Roma Camps
- ATSDR: Nitrate/Nitrite Toxicity [Big, Slow-Loading File] U.S. Government ATSDR Science Corner - 2.5MB PDF
- Water testing for Pesticides: comprehensive and pesticides-example parameters
- Water Testing: background comments on classes of water contaminants, & links to home buyer advice about water testing, drinking water, water supply
- When and How to Shock or Chlorinate a Well - Procedure for Shocking a Well to (temporarily or maybe longer) "Correct" Bacterial Contamination
- Water Requirements, Home & Outdoor Living
- Typical Water Tests & Fees this water test fee schedule applies when testing is combined with other onsite building inspection services
- Drinking Water testing, contamination, correction - all topics
- General water testing and corrective measure advice: contact your local health department.
Building & Environmental Inspection, Testing, Diagnosis, Repair, & Problem Prevention Research & Advice
The Mold Information Center: What to Do About Mold in Buildings, When and How
to Inspect for Mold, Clean Up Mold, or Avoid Mold Problems
Home Inspection Construction Consulting Services & advice for home buyers
Use this simple, economical mold test kit by following
our instructions on how to collect and mail mold samples to our lab
Environmental
Inspection, Testing, & Diagnosis On-Site IAQ, Gas, Air Testing, Mold Investigation, Sick Building Diagnosis,
Lab Services, & Remediation Plan Preparation - indoor air quality testing, problem source determination, supporting lab work, written remediation plan addressing
removal of environmental and other hazards and prevention of their recurrence.
Contact Daniel Friedman for website content suggestions or for fee-paid consulting
|