Disinfecting a well

[bluetick]

I haven't disinfected my well in some time (years). Having accepted a purchase offer on my place, the well will be tested. I need to know how much bleach needs to be poured into it to adequately kill off any nasties.

The drilled well is 57' deep and has a casing. When the submersible pump was replaced several years ago, the "static" level of the water was 14' in the month of June. I don't know the water level now, but we have had a lot of snow with some freeze/thaw cycles.

How much bleach do I need to use on it? How many days in advance of the test should it be done?

[Qvrfullmidwife]

We googled and found references for anything from a pint to three gallons. We went with three qts. We did it about 10 days before the test because unless you have a breach that stuff would be continually getting in, once you do it it SHOULD be good for a good while (years) unless you have an incident such as pump replacement or repair, flooding over it, etc.

[bluetick]

Considering the ice and snow in the vicinity of the well, and the geese making deposits on the path near it, melting could result in dirty standing water near the well head. However, it wouldn't seem that the water at 57' below would get contaminated - does it? The well head is above the ground by several inches (a foot?) and water would never get deep enough to cover the head. I suppose water could ooze down the side of the upper casing for a little way.

[Rick]

We used about 1.5 gallons of household bleach in a 50 foot well. It seemed to be more than enough, when we smelled it come through the next day.

We let it sit 24 hours. It took about 15 minutes to travel through 700 feet of 1 inch pipe.

We left that water/bleach sit in the line another 24 hours, only because we use a frost free hydrant for all water needs and did not need water until the next day. You could let it sit in your pipes for the minimum for disinfecting- something like 10 or 15 minutes- the bleach bottle probably says.

Run lots of water to purge the system of the chlorine.

Rick

[wally]

We have 100 ft well and it is pumped to a 10k gal cistern and I put 1 gal in well and 1 gal in cistern run water so bleach can clean waterlines . I do this maybe twice a year as prev maint more than any thing else..wally

[Cabin Fever]

I used about 1/2 gallon for a 100 foot well and that was plenty of bleach. Too much bleach can be counter productive.

I circulated the bleach water back into the well casing for several hours to mix. Then ran water into each of our sinks (both hot and cold valves), toliets, water heater, washing machine, etc. I let the bleach water sit in the plumbing system for 24 hours.

Here is a link to the proper method for disinfecting (shocking) your water system --> Well Disinfection Procedures

[Rick]

Originally Posted by Cabin Fever

I used about 1/2 gallon for a 100 foot well and that was plenty of bleach. Too much bleach can be counter productive.

I circulated the bleach water back into the well casing for several hours to mix. Then ran water into each of our sinks (both hot and cold valves), toliets, water heater, washing machine, etc. I let the bleach water sit in the plumbing system for 24 hours.

Here is a link to the proper method for disinfecting (shocking) your water system --> Well Disinfection Procedures

Howdy CF

Could you give an example of "counter productive" in this case. Wasted bleach and electricity costs, and pumping excess bleach in the environment are enough for me- but are there more drawbacks in putting too much bleach in the well?

Do you think half a gallon is enough to run through our 700 feet of one inch pipe?

Rick

[Cabin Fever]

Originally Posted by Rick

Howdy CF

Could you give an example of "counter productive" in this case. Wasted bleach and electricity costs, and pumping excess bleach in the environment are enough for me- but are there more drawbacks in putting too much bleach in the well?

Do you think half a gallon is enough to run through our 700 feet of one inch pipe?

Rick

The optimum concentration of chlorine for disinfection is about 200 parts per million. A concentration that greatly exceeds 200ppm makes the water too alkaline which reduces the effectiveness of the disinfection process.

I'd say 1/2 gallon of bleach is plenty for your 700 feet of pipe. That length of pipe holds less than 30 gallons of water which is a lot less volume than a typical house would have considering the volume of the hot water heater.

[wwubben]

I use the stuff from the local well man and go acording to the instructions.It requires running the water for twenty-four hours.

[bluetick]

Guess I will have a professional do it after reading your link, CF. I forgot about the electricity angle, and don't want to fool with it. I think someone dumped a whole gallon of bleach into the well the last time it was shocked. That was apparently overkill.

All responses appreciated!

[Rick]

Thanks CF.

I knew that, but forgot!

We rarely use bleach, and Ann is usually the one dealing with it.

[plowjockey]

Always dilute the bleach with water before pouring into the well.

After treatment the chlorine smelll will go away quicker than if you just dump it straight in.

[Ken in Maine]

Why not spend the thirty dollars and get the well tested yourself... Then you will know for sure. Peace of mind! If it tests good " no problem"... I don't think bleach is going to make much of a difference with nitrites... nitrates and turbidity... Those are the things that a water test will disclose... anything else would be taken care of by a filtration system.

Unless you've got a pig farm or commercial chicken operation the water should not be a problem.

Even if you do shock the well if there is a chrohic problem it will show up sooner or later and the buyer will have recourse anyway. Especially since you posted here and are somewhat admitting you have knowledge of a potential problem.

Get the well tested and sleep well tonight!

I was a plumber for 20 years and the only times we shocked a well was when we installed a new system or pump or in someway compromised the system. The bleach is only going to kill certain germs.... it will not have an effect on the overall integrity that affects the general quality of the water. A bad well is a bad well and no amount of bleach will correct that. If you've been drinking it and have had no ill effects then there should be no problems.

[Cabin Fever]

Ken in Maine, probably the main reason why people disinfect thier plumbing systems is to kill off the natural, non-harmful bacterial that live within the plumbing system such as iron bacteria and sulfur bacteria.

[Ken in Maine]

Originally Posted by Cabin Fever

Ken in Maine, probably the main reason why people disinfect thier plumbing systems is to kill off the natural, non-harmful bacterial that live within the plumbing system such as iron bacteria and sulfur bacteria.

My point exactly.. Those bacteria ( as you said "non-harmful" ) will have no issues with a water test for a real estate transaction... so it becomes a mute point as to any reason for doing it now that there is a real estate contract on the property.

[bluetick]

I was under the impression you are supposed to shock a well annually, in the spring because of increased water runoff from melting snow and spring rains. I thought I was just being lax by not having done it in years.

Maybe I will get the water tested myself before treating the well. You learn something new every day!

[Ken in Maine]

That was very common place with the older hand dug wells that were exposed to ground water contamination. Folks would pour bleach into the well to prevent contamination from ground sources.

A drilled well is far less likely to experience contamination from outside sources.

The well is drilled into the ground to ledge or bedrock. At that point the casing ( the pipe you see sticking up) is driven at least 10 feet into that bedrock then the area where the pipe meets the bedrock is sealed with a special purpose grout. That prevents any contamination from entering the well unless, of course, the top of the well pipe gets submerged and water is allowed to flow into the well casing.

There is a natural occurance in the spring of the year where you might get an off taste to you water because every body of water does something called " turn over".. I don't know exactly how this happens but water moves within it's aquifer but this is not necessarily a cause for shocking. It usually clears up in a couple of day on it own.

[Cabin Fever]

Originally Posted by Ken in Maine

My point exactly.. Those bacteria ( as you said "non-harmful" ) will have no issues with a water test for a real estate transaction... so it becomes a mute point as to any reason for doing it now that there is a real estate contract on the property.

I agree. I missed the part in the OP about selling the place and focused on well disinfection.

[Cabin Fever]

Originally Posted by bluetick

I was under the impression you are supposed to shock a well annually, in the spring because of increased water runoff from melting snow and spring rains. I thought I was just being lax by not having done it in years.

Maybe I will get the water tested myself before treating the well. You learn something new every day!

You have a couple options here. Test the water. If the results come back negative you're good to go. If the results are positive for total coliform, you're gonna have to disinfect the plumbing system and have the water tested again.

....or....

You can disinfect first and then have the water tested. The test results should come back negative...unless, as Ken stated, there is bacterial contamination of your aquifer (from feedlots, septics, etc). Disinfecting your water system will not solve that problem.

[Rick]

Question:

Are the "non-harmful", iron or sulfur bacteria, desired or undesired?