Well sanitizing (extra attention to 4 inch casing)

Discussion in 'Pumps and Tanks Well Forum & Blog. Water is life.' started by Reach4, Jun 7, 2016.

  1. Reach4

    Reach4 Well-Known Member

    Sep 25, 2013
    My favorite well sanitizing procedure that I have seen is

    However I have some added thoughts that point to needing larger flooding volume (F.V), more bleach than predicted, and more vinegar than predicted maybe.

    During the process, you recirculate water from a hose spigot to the top of the casing, you add bleach and vinegar, in turn, to the top of the well casing. This recirculation is mostly limited to area A (above pump) shown on the sketch. Area B (below pump) does not have significant flow. If you had a 5 inch casing, you could drop pellets made for the purpose to the bottom of the well. I don't think that you are usually also dropping acid pellets too, so even those with a big casing might need more flooding volume. The acid is important if your well water pH is higher.

    During the procedure, you save a flooding volume of water that can drive chlorine +acid through the casing screen. I think this flooding volume needs to be big enough to drive treated water down to fill area B and to drive the mix through the bottom screen into the nearby aquifer. If the pump is set up from the bottom a fair amount, that flooding volume needs to be larger than the numbers from the Moravec procedure.

    Some people can run a hose from a neighbor's well to provide the flooding volume (mix extra bleach and vinegar as you go). Some will have a big rain barrel or some other clean container. A new hard side "free flow" waterbed mattress can hold a lot of water. These are often sold with a venturi pump that is intended to empty the mattress. While you can do a good job with a siphon, that pump will draw a vacuum that can even overcome a little air leaking into the connection. Note that these plastic waterbed pumps have two positions: fill and empty. The water comes out of the little pump with no fitting, so that pump must be positioned over a funnel that feeds the water down the casing.

    Regarding calculations for how much bleach to use, bleach gets consumed by reacting with materials in the well. I think it is important to use some high-range (200 ppm) chlorine test paper such as Hydrion Cm-240. You won't find high range chlorine paper at a pool store, but you may at a restaurant supply house. Chlorine test strips are very useful to see how clearing out the chlorine at the end is going. Note that the chlorine to your softener should be limited. You also want to minimize how much chlorine you put into your septic. Septic tanks are somewhat resilient but I don't have any way to quantify that. I used a utility pump to send some inside water to the ditch.

    Vinegar is a good acid to use. It is not dangerous like some others. My warehouse store sells two 1-gallon jugs of white vinegar for under $4. In your well analysis, you get a pH number and you get an alkalinity number. Huh? Aren't those the same? Nope. The calcium carbonate and magnesium carbonate make the pH higher, but only to a point. They form a weak base but they can cancel out a lot of acid. The math and chemistry to take that into account is way beyond me, so I recommend using an inexpensive pH meter or pH paper that covers down to pH 5 or at least 5.5. I would like to have my sanitizing well water lower than 5.5 but 5.5 should be enough. See notes below.

    Do not mix the bleach and vinegar outside of the well. Let the water circulate one before adding the other. Take your chlorine and pH readings on the recirculating water, allowing time for the water to recirculate. You will probably need more bleach and vinegar than the Moravec procedure calculations because some will be used up in doing their jobs.

    I am sure that I take a lot longer to do this stuff than I need to. To pay somebody to do this would be very expensive, since a lot of the time is just waiting.

    Back to that picture again... when clearing out the chlorine from the well fairly quickly, you can't just run a hose from the hose spigot to the ditch. That water will come from the aquifer, through section B, and into the pump. Area A will stay stagnant when viewed in a time frame of hours. So I think to clear the chlorine, you have to continue to recirculate water through the top of the casing while you are dumping water to the ditch. This may require a hose splitter and more hose.

    Few people put much thought into sanitizing. Most people never do it, or just pour a jug of bleach into the casing when symptoms develop.

    1. Inexpensive pH meter should be calibrated before each use. The 4.01 Buffer Solution Powder packets, that you mix with 250 ml (250 grams) of distilled water, can be very inexpensive. The Pocket Digital PH Meter Water Tester Pen with an LCD display, can be very cheap. To store, fill the cap with 4.01 or 7 ph buffer solution, insert the meter into the cap, and store cap-down. That meter and buffer are often cheaper than good pH strips, and the meter is easier to interpret.
    2. If you use paper pH strips, the Hydrion pH paper range 4.5 - 7.5 (334) seems ideal for this where the target is about 5 pH. I used the more common Hydrion (067), which is adequate. Avoid the cheapest books of pH paper from China. They don't work nearly as well.
    3. This write-up is oriented to bottom-feeding deep wells with submersible pumps.
    Last edited: Jul 7, 2020
    tico007, Jrland and ChopperRS like this.
  2. jeff_bathroom

    jeff_bathroom Member

    Dec 15, 2005
    Wow, interesting info. I'll keep this url in my info file. Thanks.
    Know anything about batch solar water heater maintenance, or whether it is required periodically?
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  4. Richard Cropper

    Richard Cropper New Member

    Jan 5, 2016
    Berlin, Maryland
    Thank you Reach for that! I used the moravec procedure and that is what gave me about a years worth of no symptoms. Like you said it is alot of work I will just have to make time for it. That's why I was toying around with another way as well. Thank you!
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