Monday, January 30, 2017

Repair or Replace a Contaminated Well

Often though my blog or the Virginia Master Well Owners Network I receive questions about well and septic problems. The Virginia Master Well Owner Network (VAMWON) is an organization of trained volunteers dedicated to promoting the proper construction, maintenance, and management of private water systems (wells, springs, and cisterns) in Virginia. The Cooperative Extension Services in Virginia manages the program and have numerous publications and fact sheets that can help homeowners make educated decisions about their drinking water. The volunteers can help homeowners interpret their test results and make educated decisions about what treatment might be appropriate and desirable or appropriate solutions to problems. Last week I received the following:

My septic was leaking months before I figured it out. I had the septic repaired in September 2016. I can still smell it some when it rains on the turned up soil from the repair. Now I have found that my well is infected. I tested positive for bacteria and e-coli. I chlorine shocked my well and retested, it's back again. How long do I have to wait for my area to be clean again? Will it just be a few more months for nature to clear the area? Or could this take years?
Here are a few other details about my situation.

My well is a shallow bored well that is 30' deep, 8' water level, and 36" wide cement rings. The house, well and septic were built in 1951. My house is a 32' wide cape-cod style cinder block house with a low crawl space that sits on a lot with a nice slope from front (street) to back, which leads eventually to a ditch in my back yard that eventually leads to a stream well over five hundred yards away. The well is on the left side of the house and the septic is on the right side of the house. None of the septic field sits uphill from the well. However, the septic leaked into the ground likely for over 6 months before I figured out what was going on. The septic field moves into the back yard which is about 50 feet from the well. The septic has been fixed. I watched and they did a good job of it.

My local well company says I am getting ground water intrusion as the well is not grouted between the rings. With a simple hose I saw water leaking into the well from the surface. They want to seal the well from the outside by pouring cement around the outside and are charging me about $2,000 for it.

I want to fix the well so I don't get this ground water intrusion. However I don't think that is going to solve my bacteria problem. I have had my well water tested by an independent testing company twice now. Once in late November which started the well diagnosis, and again 6 weeks after we shocked the well. Both came back positive for bacteria and e-coli.

I'm trying to figure out if I should install a disinfecting filter or should I consider stopping all work on this well and dig a new deep well. I'm not sure if a deep well will solve my problem.

So, do I spend $2k to seal the well, plus a few thousand $ on a disinfectant and sediment filter, plus reshock the well and house a few times. Or do I spend $5-8k on a deep well. I would really appreciate some help from someone who is not trying to make a lot of money off me. I don't know how much to trust these companies.

So let’s talk about what is going on here. Her groundwater is probably flowing from the front of the house to the rear with the topography and towards the river. Nonetheless, the shallow groundwater which is what her well was tapping has become contaminated. Her well is a dug or bored wells. These types of are prone to go dry during droughts and because they are shallow (less than 40 feet deep) are more subject to pollution. Drilled wells are more than 40 feet deep, typically more than 100. This well has served this house 65 years, it’s contaminated, the shallow aquifer is contaminated- the well’s done. Do not waste money trying to grout a 65 year old shallow well.

In Virginia wells must comply with regulations in effect since 1992. While many wells like this one will last decades, it is reported that 20 years is the average age of well failure. Well failure can appear in many forms. In this case, the shallow groundwater is contaminated, she only has water because it is such are water rich area. As our writer found out, septic drainfields also have a limited life. The life of a septic drainfield is dependent on how the system is managed, the frequency of septic tank pump outs, and the number of people living in a house, but 20-30 years may be the life of those systems, too. It is good bet that the septic system had been failing for much longer than 6 months.

To provide the best natural protection and prevent contamination to a well regulations in Virginia and several other states require that the well should be 100 feet from the nearest edge of the septic drainfield and 50 feet from the nearest corner of the house. If the land area is small, the way to to separate the two as far as possible is to use vertical separation- with the septic drainfield downgradient of the well go deep with the well. In Virginia (and most places) if a well is more than 100 feet deep the septic leach field need be only 50 feet away, but there are many wells like mine that have more than one water level and the shallower one is less than 100 feet deep (in my case 46 feet) making the well much more susceptible to contamination for the septic effluent leaching into the ground. You must make sure that the well is lined, grouted and the geology protects you from the drainfield to prevent the new well from being impacted by the septic system.

She mentioned that her well was contaminated with E. coli. Fecal coliform is the group of the total coliform that is considered to be present specifically in the gut and feces of warm-blooded animals. E. coli is considered to be the species of coliform bacteria that is the best indicator of fecal pollution and the possible presence of pathogens. If there is not a nearby animal waste composting facility, then you are probably drinking water from a failed septic system- yours or your nearest neighbors or both. To solve this problem you need to fix or replace the septic system that is causing the contamination, replace the well or implement and properly maintain the right water treatment system. Even if a failing septic system is repaired, it can take months or years for the contaminated water to dissipate depending on a variety of factors including, depth of the well, groundwater flow and geology. In the meantime, you need to treat your water. Understand that if your well has been impacted by a failed septic system, it has been contaminated not only by fecal contamination, but also by everything else that ever went down the drain. Cleaning solutions, paint, detergents, etc.

To properly treat well water that has been impacted by E. coli or fecal contamination, you need to disinfect the water using either a UV light or continuous chlorination. Your choice of systems should be based on personal preference and what other contaminants are present in your water. Both disinfections systems require that you have a reverse osmosis system with a one micron membrane for removal of Giardia or Cryptosporidium which are potential deadly contaminants from a failed septic system. Remember that your reverse osmosis system should by-pass the septic system for its waste water discharge. For more details on optimizing a home treatment system see

The bottom line is our questioner should pay $5,000-$8,000 to drill a deep well.

1 comment:

  1. For Blue Ridge and Piedmont wells, I agree with you - Drill deeper with proper casing into the fractured bedrock. I would also suggest inspection and 5-year septic pumpout.