OK, you’ve got a positive bacteria test. Now what??
First, you need to re-check your sampling techniques. Did you take the sample from a hose bibb or yard hydrant? Did you remove the aerator? How well did you soak the faucet threads with alcohol? Was the sample taken outside and what were the weather conditions? How long was the lighter actually heating the faucet threads? Did you place the sample bottle lid top down on a dirty surface?
Any or all of these things can affect the quality of the test. Minor contamination of the testing materials (such as the cap, bottle, the faucet area, etc) may cause a false positive. Paying strict attention to the recommended guidelines for taking the sample will pay off for you. Sampling procedures are designed to minimize sampling error and short-cutting of those procedures will increase the probability that you will have a positive bacteria test.
Secondly, was the sample taken from a well or a spring? We will discuss some common well issues first and spring issues last.
Let’s look at the construction of the well itself. When was the well drilled? Was it drilled in the last 30 years or prior to that? Where is the location of the well? Is it near a septic tank or field, in the middle of a farmer’s field, or next to the foundation of a building? Does the well casing extend above the surface of the ground or is it “below grade”? (ie. in a pit in the ground) Was the well buried? Is the ground highly-fractured stone or compacted dirt? Does the ground surface slope towards the casing?
If you answered “yes” to any of the above questions, then you may have a well construction issue in your hands. If the well was recently drilled or the pump replaced/repaired, was the well chlorinated afterwards? If it was not chlorinated, then a simple chlorination may take care of the problem. Any combination of these factors could be enough to cause coliform contamination. If that is the case, you may need to call a qualified well driller out to inspect your well and to make some recommendations for remediation. One of these recommendations will probably involve sanitizing the well.
If the sample was taken from a spring, then there is a very good possibility that you will have a positive total coliform test. In southwest Virginia, there are few springs that were developed properly and in such a manner as to minimize penetration of surface water and to maximize penetration of ground water. Whenever the primary source is surface water, it is highly likely that you will have a positive total coliform test. This applies to shallow wells as well as springs.
But, the first place to start looking for spring problems is the spring box. What was it made of? Concrete? Plastic? Do you even have one? Does it have a lid and does that lid seal tightly to the sides of the box? If you see living animals such as frogs, salamanders, spiders, etc inside of the spring box, that is enough evidence that your lid does not seal. A visual inspection of the condition of the spring box itself may be a good indicator as to whether or not repair or replacement is recommended. Examination of the inlet pipe for the spring box may also help. If you can see daylight through the pipe, then it is another good indicator of a source of the problem. This pipe should be buried in an area that has been properly prepared to handle water collection and covered with a fine-meshed screen. Examination of the outlet pipe is also important. There should be another fine-meshed screen placed over the outlet pipe to limit introduction of foreign materials.
Once you have established a likely source of contamination, you really have two or three choices that come down to the question of what is cost-effective for you to do.
- Fix the problem at the source (ie. well or spring).
- Hook up to munipal water (if it’s even available).
- Or treat the water as it comes into the house with a water treatment system that includes a filter to remove any particles, potentially a softener if you have hard or iron water, and an ultraviolet system to kill the bacteria.
We can help you to answer that question and give you the tools for you to determine your next move.
-Andrea Jones, Laboratory Director