A Guide to Domestic Water Wells, by Olive

Wednesday, Jan 6, 2010

The recent post regarding the found well inspired me to write a note that I’ve been meaning to share.
I work in the water well industry, specifically the troubleshooting of problem wells.  The thing that continues to surprise me is the wide range of beliefs and lack of solid information on well systems. I say systems because an owner/operator must view a well as a sum of parts, more than just a hole in the ground.

The first issue I’ll address is testing. Most states and local health departments have settled on the coliform test as the only means to pass judgment on a well. This is a big error in my opinion. This test is often misrepresented as a “Bac-T” test and is assumed to include all bacteria by professionals and laymen alike. Coliforms are one family of organisms and include everything from E.coli related bacteria to naturally occurring soil bacteria. Bacteria are found everywhere, and it is impossible to find a well that does not have resident bacterial populations, no matter how deep or where it is located. If a test has been performed or is required, find out what type of test and results you will get. You want more than just a presence/absence, you want to know what is there and how many. There are a variety of online sources that you can then read up on the identified bacteria and find out if it is a problem or not.

The second issue is well head protection. This has become more popular in recent times, but the effort is focused mainly on larger well systems. In my opinion, it is more important for the residential or “back-yard well owner” as they do not have the treatment systems in place nor the mandatory testing requirements. So, for the SB readers, I recommend:

  1. Examine the well and area around the well head. Identify any conduits or drainage that may impact the well or the area adjacent to the well. If there is any area of erosion or subsidence (ground collapse), seal with Bentonite (well seal or well plug) and back-fill the area. Manage the drainage in the area so that no flow impacts the well or settles near the well.  If you have a “well house” – examine it for leaks and possible rodent use. Clean it out and check it regularly. If you have a concrete well “pad”, make sure it is not being compromised or that erosion is occurring underneath it.  You may need to stabilize and manage drainage around it too.
  2. Collect information. Now that you’ve addressed the topside, scour all possible records for well data. This may be very difficult – if you cannot find information on the well, contact a driller or pump installer and schedule a visit. You want to know the age and dimensions of your well (depth, diameter), the type of completion (steel, pvc, screen, or open borehole), static and operating water level; type, age, and efficiency of the pump. Knowledge is key! Why? All means of operating, cleaning or disinfecting the well are dependent on the size of the well!

One note, for those with “hand-dug” wells, you may want to consider lining or replacing the well. These types of wells are often natural cisterns or collector wells and can have infiltration issues that may cause more problems than good.
The next issue we tend to deal with is fouling. Fouling occurs as a number of issues – it can be bacterial presence, hard scale build-up, the accumulation of sediment, or a combination of each of these issues. Fouling in a filter or pressure tank may reflect greater problems downhole. More often than not, the problems occur do to the inactiveness of the well. 

  1. Keep the Well Active! Bacteria, present in biofilm and biomass generally contract during periods of flow in and around a well system. As the flow decreases, the biofilm expands as the need for nutrient capture grows. During expansion of biofilm, populations also swell. Bacteria are most active in stagnant water situations, as they seek to capture necessary for growth and propagation. Similarly, as the flow of a well system decreases, the entrance and influence of oxygen on the system decreases. This can lead to more anoxic or anaerobic environments to occur. As anaerobic conditions develop, the growth and development of anaerobic bacterial populations increase. Anaerobic bacteria are often the more troublesome bacteria. First, they typically include sulfate reducing bacteria that can impart a “rotten egg” or hydrogen sulfide type odor on produce water. Second, the biofilm produced by these bacteria is typically more dense and problematic with regards to fouling potential. Lastly, many Coliform bacteria are facultative anaerobes and take up residence in anaerobic environments. In some cases, water sitting idle for only a couple of hours in the well can become ripe with bacteria and cause significant plugging to occur within the well. In addition to restricting anaerobic growth, operational wells continually purge debris from the system, preventing accumulations from occurring within the borehole. Hardness loss and geochemical congestion are also limited in active well systems. Corrosion, resulting from over pumping and a variety of factors, can be reduced as well.  I understand that many use wells as back-ups or for emergency needs. You need to investigate methods of cycling the well – even if for just a limited time. There are a variety of timers and triggers that can be used. Solar powered systems and floats can be very beneficial in maintaining effective storage while also regularly exercising the well.
  2. Treating the Well. If and when it comes time to have the well cleaned or disinfected, take the time to do it right. The number one issue we find in failed well cleanings is the failure to evacuate the bottom of the well. The bottom of the well acts as a sump, often collecting sediment as well as organic debris. As mentioned above, this can plague a well and also reduce the effectiveness of cleaning efforts. Additionally, have the contractor find out what the problem is and design a specific treatment, don’t just have them do what they normally do to any well…each well is different! If chlorination is deemed necessary for disinfection, use a concentration of fresh, liquid sodium hypochlorite (to reduce the influence of calcium) between 100 and 400 ppm. Never “shock” chlorinate a well with concentrations of chlorine over 500ppm! Also, buffer the solution to a pH of 6.5 to 7 – this will maximize the effectiveness of disinfection that is often reduced by the DOT required shipping pH of 9 to 11 of chlorine.

So many people treat wells as just another object, assuming that when the time comes, it will be there and ready to use. Nowadays, with costs increasing and some states limiting the drilling of wells, vigilance is more important than ever. Treat your well as an asset – possibly your most precious asset. Check your well periodically for corrosion, increased air, foul odors or discoloration. If possible, purchase a test kit and track the quality of your water. Each of these can be a sign of trouble downhole. Identifying problems early is often cheaper to respond to and you have a greater chance of success. I also recommend that you contact your local extension office or county sanitarian; periodically these agencies may offer workshops regarding wells and private water supplies.


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