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Disinfection and Testing


The Effect of chlorine on the pH of water: (under construction)

Generally speaking the more chlorine you add the higher the pH and the less effective the chlorine becomes as a biocide.  This means you won't kill bacteria as much or as efficiently as you should unless you control the pH of your water.  

When chlorine is mixed into water pH rises dramatically.  Chorine is 100% biocidal at a pH of 5.5 but is 100% oxidative at a pH over 10.  When 50 ppm chlorine is mixed into water with a natural pH of 7.1, pH will rise to 7.6.  The biocidal effectiveness is now 34%.  As pH rises, chlorine becomes more oxidative in nature.  When 200 ppm chlorine is mixed into water with a pH of 7.1, the pH rises to 8.1 and the biocidal effectiveness decreases to 9%.  So you can see that by adding more chlorine is not always better or more effective.

Basically we need to control the pH of your water during the disinfection of your well.  Follow these procedures and the process should be much more effective that just dumping bleach down your well.  REMEMBER THE ONE THING THAT SHOULD BE YOUR GOAL!  Get the disinfection chemistry in every part of the well and distribution system.  Casing rises and falls between pumping cycles.  'Dead' zones in piping can hide bacteria.  Get the chemistry everywhere!



CAUTION:  Hypochlorite solution (chlorine) added to water with a pH below 5.0 will release chlorine gas, which is extremely toxic.  This procedure should only be done in the open with good ventilation.  Do not mix vinegar and chlorine together above ground.  Always mix solutions in well with water circulating using a clean garden hose or in a clean pail of water.  The use of gloves and eye protection is recommended.

All procedures based on regular 5.5% bleach, not scented or ultra.  Must be new product due to reduction in potency with shelf life.


1.  Determine the amount of water in the well (Standing Well Volume, SWV).  This is accomplished by knowing the total depth of the well and subtracting the depth to water multiplied by the gallons per foot the well can hold.

SWV = depth of well – depth to water x gallons per foot in well

6” well retains 1.469 gal/ft.

8” well retains 2.611 gal/ft.  

2.  Consider the general water quality of your well.  Does it have hard water, high iron, sulfur or gas?  These conditions in high levels will influence the effectiveness of the disinfection of the well.  Select either Table A or Table B for the disinfection quantities.  If the water does exhibit high hardness or presence of methane gas, double the amount of pH control (vinegar).  This will compensate for the elevated alkalinity these conditions are typically associated with.

3.  Take your SWV and find out on the Table what quantities you need and have them on hand.  Also have on hand enough 5 gallon pails to use for the Flooding Volume at the end of the procedure.


4.  Start the disinfection procedure by running a clean garden hose to your well.  Fill the required volume of water for the flooding of the well into the pails.  Then place the hose into the well (making sure you don’t get the wire connections wet) to circulate the water.

5.  Pour the required amount of vinegar into the well followed by the required amount of chlorine.  Continue to circulate this mixture at least 20-30 minutes after chlorine can be smelled coming from the hose.  This may last for at least 40 or more minutes. Make sure the casing is disinfected by washing it down with the hose. 

While this mixture is circulating, mix the flooding volume.  Flooding Volume is the amount of water held available at well head (usually in clean 5 gal. buckets) to be poured into well at the completion of the disinfection procedures.  To mix: add ½ cup vinegar and ¼ cup chlorine to each 5 gallon pail of water.

  6.  Once the well has circulated the required time, turn off the hose.  Go into the house and run the water at each cold water tap one at a time until chlorine can be detected.  This means every outside spigot, shower, toilet, faucet, washing machine or dish washer, anywhere cold water flows to.  Run hot water only 10 to 15 seconds to disinfect inlet to hot water tank.  If you question your system, then by all means run the hot water as well.  The hot will be discolored much longer in order to flush the large volume of water from the hot water tank through the system.

  7.  Wait approximately 30 minutes for the well to recover.  Then go back to the well and pour the pails of dosed water (flooding volume) into the well.  You will have effectively created an artificially high water level that will fall to the normal static level. A well that makes water will take water.  You have now accomplished disinfection outside of the well itself and into the surrounding bedrock or sand and gravel.  Close the well up. 


  8.  Allow the well to set at least overnight with only minimal use.  Two days is better.  I wouldn’t wash your hair with it unless you want to be a bleached blond.  You can flush toilets but don’t over do.  Too much chlorine is not good for septic systems.

  9.  After the system has been allowed to set it can be flushed to remove the chlorine and the discoloration that usually accompanies this procedure.  If the well produces greater than 4 to 5 gallons per minute the well can be flushed by opening the garden hose at a 1 to 3 gpm rate and discharge the water from the well to an area where the grass won’t be burnt.  If the well produces less than 4 gpm discharge the water slowly (<1 gpm) as above or discharge ½ the volume in the well and use normally until odors and discoloration dissipate.

  10.  If you are disinfecting your well as simply a maintenance procedure you are almost done.  Once you are getting chlorine free water again, take the hose back to the well and rinse the steel well casing down.  This will stop unnecessary oxidation of the steel.

If you are disinfecting your well to obtain a C of O as part of a new home or property transfer, the next thing to do is to get ready for proper sampling of the well.  See Proper Well Sampling Protocol.

The information and recommendations contained in these handouts have been compiled from sources believed to be reliable and to represent the best opinions on the subject as of 2003.  However, no warranty, guarantee  or representation, expressed or implied, is made by Barney Moravec, Inc. as to the correctness or sufficiency of this information or to the results to be obtained from the use thereof.  It cannot be assumed that all necessary warnings, safety suggestions and precautionary measures are contained in these handouts, or that any additional information or measures may not be required or desirable because of particular conditions or circumstances, or because of any applicable U.S.A. federal, state,  local law, or codes.  The warnings, safety suggestions and precautionary measures contained herein do not supplement or modify any U.S.A. federal, state, or local law, or any insurance requirements or codes.



  Table A.  50 ppm Disinfection quantities for average well water quality  

(i.e. no gases, no sulfur, low to moderate bacteria and low to moderate hardness)  


Table based on regular 5.5% bleach

Standing Well Volume


Flooding Volume (gallons)

pH Control *

(white vinegar)

Food Grade

Chlorine **



50 5 1 ½ cups 1 cup
100 10 3 cups 2 cups
150 15 1 quart 2 ½ cups
200 20 .33 gal. (5 ½ cups) 3 ½ cups
250 25 .41 gal. (6 ½ cups) 1 quart
300 30 .5 gal. (8 cups) 5 cups
350 35 .58 gal. (½ gal + 1 cup) 6 cups
400 40 .66 gal. (½ gal + 2 ½ cups) 7 cups

  Table B.  200 ppm Disinfection quantities for more difficult well water

 (high iron (Fe), sulfur, iron or sulfide bacteria, methane or hydrogen sulfide gas)


Table based on regular 5.5% bleach

Standing Well Volume


Flooding Volume (gallons)

pH Control *

(white vinegar)

Chlorine **



50 5 .33 gal. 5 ½ cups 3 ½ cups
100 10 .66 gal (½ gal + 2 1/2  cups) 6 ½ cups
150 15 1 gallon ½ gal + 2 cups
200 20 1.32 gal (1 gal + 5 cups) ½ gal + 5 ½ cups
250 25 1.65 gal (1 ½ gal + 2 cups) 1 gal + 1 cup
300 30 2 gallons 1 gal + 1 quart
350 35 2.31 gal (2 gal + 5 cups) 1 ½ gallons
400 40 2.64 gal (2 ½ gal + 2 ½ cups) 1 ½ gal + 3 cups

  * Double amount of vinegar to be used if water exhibits excessively high amounts of hardness or presence of methane gas.  Use white vinegar (food grade).

  ** Recommend using NSF or UL approved chlorine.


In the event that you do not know your well depth, depth to water and therefore well volume, you can use a larger scale well flooding technique that can accomplish a great deal of bacterial disinfection.  This technique has proven very effective on wells set up for storage systems and or other low producing water wells.  Again use the above tables to create the proper chemistry for a specific flooding volume. 

Basically, a well that makes water will take water.  What this means is that every well has its own static water level and when you add water (or in this case disinfecting chemistry) to a well, the water level will eventually reach this original static water level.  The idea is to flood the well and the surrounding water producing formation adjacent to the well with disinfection chemistry. This is done in an effort to reduce or sometimes eliminate bacteria growth that can plug up a well.  This technique requires a tank(s) of water that you will mix the chlorine and vinegar in.  This volume is then placed into the well to flood it with chemistry.  While flooding the well, you can circulate the chemistry in the well with a garden hose as described previously to ensure mixing and washing the casing down with disinfectant.  Follow all previous directions to ensure that the disinfectant reaches all portions of the pumping and piping system. 

Allow the proper waiting (contact) time for the disinfection chemistry to do its job and then pump the well out to waste and dispose of properly.  Allow several days for the well to clear up.  If significant bacteria debris was removed and an improvement of the well was noticed it may be beneficial to repeat this process in 2-3 weeks.  Doing this a second time may remove additional layers of bacteria and improve the effectiveness of this technique.

NOTE:  Please make sure there are no other wells nearby that could be affected by this flooding technique.  Turning your neighbors hair to strawberry blond may not go over very well!


There are a few important things to remember when you have a storage system.  The first is to set the system up so that you DO NOT completely remove the water in the well when filling the storage tank.  This will only promote bacteria growth by putting more oxygen into the well.  Take just enough water from the well to keep the tank filled...just like taking the cream off the top of milk.  To accomplish this, make sure there is a timer or at least a flow restrictor included in the system.  Additionally keep the float switch in the storage tank near the top.  By making sure the float switch turns on near the top of the tank this will assist in not over-pumping the well.  Remember, if the well only makes 1/2 gallon per minute times 1,440 minutes, that is 720 gallons per day.  If you have a 180 gallon tank and you need 100 gallons per day per person, set the timer to fill 300 to 400 gallons per day.  The tank will always be full and the well will not be over-pumped.

Note: You can also add a little vinegar and bleach once a month to help control bacteria in storage tanks.


1.  Poor sample collection.  If you haven't taken your aerator off the tap and not disinfected the sampling point it probably will not pass.

2.  Integrity problem with the well.  This is usually caused because the well cap is not sealed and bugs can get in.  This matters.  Other well bacteria causing problems include: improperly installed pitless adaptor (connection to the house), broken casing, not enough casing.  All of these conditions are somewhat common and can be diagnosed.

3.  Pump installation or repair that had the well assembly laid on the ground thus picking up what ever it was dragged through...yummy!  Just think, a brand new, clean well just contaminated.  If a well is repaired it should be disinfected when the work is completed.

4.  The pump was installed high in the casing (not near the bottom).  In this case there is a 'sump' area that is created and not disinfected.  This area may not be reached without flooding it with disinfection chemistry, adding dry-pellet chlorine tablets that would make it to the bottom or cleaning by a drilling rig.


  1.  Get sample bottle from an approved New York State licensed laboratory.  Get small cooler with ice in it, latex gloves and isopropyl alcohol (rubbing alcohol) preferably 91 % (70% will work).

  2.  Remove aerator from the sampling point faucet (usually kitchen sink).

  3.  Clean the faucet, the threads and as far internally as possible with paper towel and either isopropyl alcohol or bleach.  Try to squirt some disinfectant into the faucet.  Let stand 4 to 5 minutes.

4.  Run water slowly for 4 to 5 minutes.  Note: water must be free of sediment, color and chlorine prior to sampling.

  5.  While water is running, label the sample bottle properly.  Then rinse latex gloves or if not available your hands with isopropyl alcohol to disinfect them.

  6.  After running the water for the required 4 to 5 minutes, open the top of the sample bottle without touching the inside or even the top.  This can be done by using your thumb to lift and pop off the top.

 7.  Place the bottle under the slow stream of water until it reaches the fill line.  DO NOT over fill the bottle and dump out some.  This will likely cause a false positive.  Immediately close the top and seal.  Place on ice (lab won’t accept unless cooled), keep out of the sun and deliver directly to lab or drop off location. 

BMI has a sample drop off at the office in Penn Yan for Life Science Laboratoies in Syracuse, New York.

  IMPORTANT:  If this is a re-test, do not get alarmed.  The report of coliform is only an indicator of a potential problem.  A positive for coliform can come from any number of places and for any number of reasons.  When you eat chicken wings, you get coliform.  A positive for e-coli is considered much more of a concern.  Normally, bacteria results are reported as present or absent.  Particularly on a second or third sample this is inadequate.  Therefore request an MPN (bacteria count).  This may cost a little more but it at least will give you a quantitative value to help determine the severity of the problem causing the positive results.  If you do receive a second positive result, please do not hesitate to contact BMI to go over your particular situation personally.

If you have any questions regarding these procedures or protocol, please drop us an e-mail at This email address is being protected from spambots. You need JavaScript enabled to view it.  or call us at 315-536-3911.



Is your well going dry?  There are a few things you can do before drilling a new well. Maybe there is a pump problem. Or...

If you have a shallow dug well and you have less than 1 foot of water or no water, you really don't have too many choices except for waiting for the water table to recover, maintaining a separate water storage tank that you would have water delivered to or drill a new well.

If you have a drilled well that can still recover water, you may have a biofouling problem that is limiting the flow of water in the well.  In this case you may be able to at least temporarily improve this flow and get through the drought.  This is the procedure.  Have potable water delivered to your well.  Before the water is added to the well, add both vinegar to lower the pH of the water then add either a well sanitizer product or preferably sodium hypochlorite (regular clorox) we recommend an NSF approved chlorine.  Circulate this mixture for 30-45 minutes and then add the delivered potable water until it reaches the top of the casing.  This will create a positive pressure on the well.  What this is doing is to effectively forcing the solution back into the water bearing zones in the well.  Hopefully this will begin to remove the biofoul that may be causing your problem.  If you are going to try this, check out our Disinfection and Testing Page or contact BMI for instructions on the proper mix of vinegar and chlorine.

New Regulations For The Water Well Industry In New York!

As of January 1, 2000, anyone obtaining water for economic use  is considered a well driller and must register with the New York State Department of Conservation (DEC).  Anyone who works on a well or well pump, new installations or repairs, is considered a well driller and must be registered.  The DEC has a registration system in place.  You can check that we are registered at  Soon all registered drillers will have to be certified and will carry an identification card.  The New York State Department of Health (DOH) have implemented new standard for water wells as of November 23, 2005. 

What this means to you:  By law your well driller or pump installer must be registered with the State of New York.  Barney Moravec, Inc. is.  Anyone that works on a well (including pump installations) for profit must be registered with DEC.  This law also requires the driller to be adequately insured.  And most importantly, your local code enforcement officer will be aware of these new regulations and has the authority to enforce them.  They can request the registration number of your driller and insurance certificate.  If they do not receive this information, they can stop work on your project or not issue a certificate of occupancy.  They can also request other information about the well that you may have to provide.

The drillers and pump installers at Barney Moravec, Inc. have already taken and passed the certification exams prior to 2003.  We are and always have been fully insured.  Our DEC Registration number is NYRD 10024.  This decal is posted on all of our equipment. 

Things To Consider...

If drilling a water well is a new step for you or even if it's old hat, there are many things that you may not have thought of in planning for your new well or in maintaining your existing well.  Barney Moravec, Inc. tries to be as informative as possible in order for you to make the best decision possible.  Here is a list of things to think about when trying to decide what to do with your situation:

Are You Drilling a New Water Well?   

  • Get an option to buy if possible!  If you don't own the land yet, don't buy it until you know it has a useable supply of water.  It's better to be out the cost of a well rather than owning a piece of property with no water on it.  This is a rare occurrence but better safe than sorry.
  • Where is the septic system going?  Keep the proper distances from the septic tank and leach lines (including neighbors).  New York State recommends that the well is located at least 50 feet from the septic tank and 100 feet from any leach line.  If you are forced to be down-gradient of the septic, they want the well to be at least 200 feet from any leach line.  For public systems it is always 200 feet.  Think about neighboring pasture areas too.  Notice:  the new DOH regulations have changed the way we evaluate separation distances.  The 50 and 100 foot rule is still in effect unless you have less than 50 feet of casing in your well and in that case you need to add 50% to the separation distances.  Unfortunately, you don't always know how much casing you will have in your well.  Therefore, in almost all cases, keep the well 150 feet away from the nearest leach line of the septic system.
  • Maintain Access!  Make sure there are no over-hanging wires or branches over the well site, now or 20 years from now.  If you are planning to build a pool or barn etc., make sure you can always work on the well.  If a pump ever fails you will need access.  Do not build over your well.
  • Can you get a rig to the location to drill?  You can't always put a drilling machine on a steep grade or a wet location.  Sometimes an area with a lot of topography or trees has to be leveled before a rig can get to the site.  You may first need us to conduct a free site inspection.  Selecting the best location may save time and money.
  • 8" vs. 6"  Do I need extra water storage in my new well or a separate storage system? When planning your new well, we will discuss your water requirements with you.  Depending on where you are planning to drill, you may want to consider a larger diameter well.  It is a geological fact that some areas do not produce a great deal of water.  If you happen to be in such an area, then a large diameter well may be a very prudent choice for you. For instance; a 6-inch diameter well contains 1.469 gal./ ft., an 8-inch well stores 2.611 gal. / ft..
    In some instances, a separate storage system is required.  This system can be installed in the ground or in a basement.  Remember, 1 gallon per minute doesn't seem like much water but in 24 hours it equals 1,440 gallons.  A normal household doesn't use that much water.
    The decision to go to an 8-inch well ultimately rests on you.  However, we won't recommend it unless it is the best choice for your location and planned use.  Cost becomes a factor also.  Essentially the difference between a 6-inch well and an 8-inch well is just over $700 per hundred feet of drilling.  Storage systems installed even by the owner will cost over $1,700 and up to $4,800 if someone else is paid to do it.  To us, an 8" well is an insurance policy in case you get a low producing well.
  • Do I need water for construction or analytical test?  For new construction we often install the well pump immediately after the well is drilled.  This allows for any testing required by the town building inspector and provides water for the contractor.  The contractor may charge for water if it isn't on site.
  • Are there any underground utilities on your property?  We routinely call Dig Safely New York formerly Underground Facilities Protective Organization (UFPO).  However, you may be aware of such underground services that we want to know about in case someone makes a mistake.  BY LAW the person or company that is conducting any excavation must notify Dig Safely New York (outside NYC and L.I.) at 1-800-962-7962.

Well Maintenance...It's Your Investment!  

  • Keep your well secure!  Make sure the cap is tight and has no cracks in it.  Kids love to drop things down holes and that will get very expensive.  Do not place potential contaminants near your well or up-gradient of your well.  Install a vermin-proof well cap that will keep the bugs out...we have them in stock and offer them on every well we drill.
  • Disinfect your well.  As a regular maintenance item, you should disinfect your well either annually or semi-annually.  We have a specific disinfection procedure with directions on the quantities of disinfection materials to be used (see our new Disinfection and Testing Page).  There is such a thing as too much chlorine.  In fact we are now using white vinegar as part of the process.  Disinfection not only cleans your well but helps control other things that can reduce the production capability of your well.  REMEMBER...MORE CHLORINE IS NOT BETTER.  You can actually put too much chlorine in your well and cause more problems than you already have.
  • Test Your Well.  Once you have a new well it is your responsibility to maintain it and care for it.  We provide literature for your to do just that including a handout on proper sampling of your well.  In addition, it is important to check your water by testing it 1 to 2 times a year for at least total bacteria and if there is a concern, nitrates.  This will give peace of mind and confidence in your water supply.  Nitrates should seriously be considered especially if the residence will have infants drinking the water.



When you're sick you go to a Doctor.  When you have questions about wells you should contact a water well professional.

Please call us.  There is so much incorrect information out there about wells.  The one fact we want you to remember is, that there is no better source of drinking water than water from a properly constructed well.  Additional information is available on excellent sites for the well owner from the National Well Owners Association at:

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Things to Concider

  • Radiant, Forced Air or a Combination of Both
  • Insulation and Air Sealing
  • Timing of the processes involved
  • Vertical or Horizontal
  • Design and Sizing of the home
  • Installation
  • Tax Incentives