My Plan of Attack for the Coliform in My Well

The 2015 Prince William County water clinic found that almost a quarter of the wells tested present for coliform bacteria-this was a lower percentage than in years past. However this year my well was one of the wells that found coliform bacteria present. This is a problem that should be address immediately, but is not a reason to panic. Properly addressing coliform bacteria is not really difficult, just time consuming and inconvenient. Standard protocol is:

1. Carefully check the well and water system for points of contamination and retest to verify the result making sure to use proper sampling procedures. 
2. If the sample still tests positive for total coliform then treat the well and plumbing system with 50-200 ppm chlorine for 12-24 hours to disinfect system. Then flush the chlorine from the system.
3. Retest the water after the chlorine has left the system in about 10 days to two weeks. Confirm the testing again after the next big rainstorm.

Coliform bacteria are commonly found in soil, on vegetation, and in surface water. They also live in the intestines of warm-blooded animals and humans. Some coliform bacteria strains can survive in soil and water for long periods of time. Coliform bacteria will not likely cause illness. Coliform bacteria do not occur naturally in most groundwater aquifers. However, fractured or creviced bedrock aquifers that are close to the surface are the exception and testing for E. coli and fecal coliform and nitrogen will help differentiate coliform from contamination that might impact your health. Disinfecting the well, well cap and entire plumbing system will let me know if I have a persistent coliform problem.

There are three different groups of coliform bacteria; total coliform, fecal coliform and Escherichia coli (E. coli) each has a different level of risk. Total coliform bacteria without the presence of E. coli bacteria is generally an indication of surface contamination introduced into the well. Generally, this type of bacteria is introduced by a failed well cap, improper sanitation after a well service or failed grouting or from the fractured rock system. Last winter I had my well cap replaced because the old one had failed. That is probably the source of the coliform, but I cannot be certain.

Coliform bacteria are not a health threat itself, it is used to indicate other bacteria that may be present and identify that a well is not properly sealed from surface bacteria. The federal standard for coliform bacteria is zero, but the federal standard allows that up to 5% of samples can test positive for coliform during a month. Fecal coliform and E. coli are bacteria whose presence indicates that the water is contaminated with human or animal wastes which is a much bigger problem.

My well was found to be contaminated with coliform but not E. coli, so I have a nuisance bacteria problem and the source may be infiltration from the surface from rain or snow melt or the repair last winter to my well. Typical causes are improperly sealed well cap, failed grouting or surface drainage to the well. I am hoping that this coliform problem was introduced when the repair was made and can be swiftly (and permanently) fixed by chlorine shocking the well.

Keep in mind that coliform bacteria do not always show up in every sample. They can be sporadic and sometimes seasonal when they occur in a water supply. Though it is recommended to resample before treating the system, I am going to skip that step and go directly to boiling all drinking water and getting set up to disinfect my well. If you receive a second positive sample for total coli forms, or if the initial sample is positive for E coli, do not consume the water. Bring the water to a rolling boil for one to five minutes (the higher the elevation the more time is necessary) to kill the bacteria. You may also want to consider using bottled water as a temporary drinking and cooking water source.

The reason I am going to immediately disinfecting my well is that treating a well with chlorine also cleans out the well and eliminates iron reducing bacteria that I have had problems with in the past. I was actually thinking of treating my well with chlorine sometime this year anyway. Shock chlorinate the well, disinfect the entire plumbing system, repack the soil around the well pipe to flow away from the well and wash and disinfect the well casing and well cap. Sounds simple when I write it out, but disinfecting or shock chlorinating a well and plumbing system is a lot of work and really a two person job especially when one of the people has a touch of arthritis in her 60 year old hands and cannot loosen bolts.

The Virginia Rural Household Water Quality Program recommends that if you are not an experienced DIY that you hire a well driller to do it for you. I would love to have paid someone to just do this for me, but I could not find a well driller I respect who has time for such a small job. Really though the hardest parts are opening the well head, and draining and treating the hot water heater, dishwasher, washing machine and ice makers. Everything else is just prep work, setting up hoses, and generally knowing what to do. So I called my very kind plumber who is willing to rent me his son (a journeyman plumber) this week for two mornings.

Then after two to three weeks I will retest my well for coliform bacteria and then test it again after the next big rainstorm. I’ve just ordered 12 coliform home testing kits that should be here tomorrow. If I find coliform is still present after a complete and thorough disinfection then I will immediately install a long-term treatment system. I will install a UV light system for continuous disinfection. These systems can cost up to $2,000 installed.

I plan to disinfect my well Wednesday. Meanwhile I need to prepare. So tomorrow I am going shopping for supplies. I need to buy: a plastic tarp, 3 gallons of Chlorox (Three gallons is about twice what I need to disinfect my well and plumbing. If a lot of crud comes up when I first recirculate the chlorine I will flush it before I let the water into the house and start again.), an 8” diameter funnel, chlorine test strips, coliform bacteria home test kits, 12 gallons of bottled water (to carry us while we have no water to use), new refrigerator filters, rubber gloves, a 5 gallon bucket. Then I need to wash my hose that I will use for recirculating the well water.