ETR Laboratories has tested drinking water since 1995. We have processed hundreds of thousands of water samples. We also completed over 1,000 in-field well inspections. That kind of volume creates something no algorithm can replicate: real patterns. These patterns emerge from years of close attention to data and to what clients tell us about their water. Below are six of the most important lessons we have learned, things many testing companies never think to look for.
1. A Low Bacteria Count Can Be a Warning Sign, Not a Green Light
Most water testing companies report a low bacteria count and call the water clean. At ETR, we learned years ago that a low count is not always reassuring. It can actually point to a more serious problem underneath the surface.
Over years of comprehensive analysis, we noticed a consistent pattern. Clients would call describing smelly water, a rotten egg odor classically tied to bacterial activity, but their standard bacteria counts came back with just one or two colonies. On paper those results looked fine, but something did not add up.
When we dug deeper with full microbiological analysis, we consistently found elevated fungi counts in those same samples. We were witnessing a natural antibiotic effect. Certain molds, with Penicillium being one of the most common, produce compounds that actively suppress bacterial growth. They keep bacteria colony counts artificially low while the underlying contamination problem stays very much present.
A suppressed bacteria count combined with a high fungi count and odor complaints is a red flag, not a clean bill of health. This is one of the reasons we developed our BioScan Microbiological Water Test, which goes far beyond a standard coliform test to examine the full biological picture of what is living in your water.
2. Nitrates in Private Well Water Mean Something Completely Different Than in City Water
The EPA sets a maximum contaminant level for nitrates in public drinking water at 10 parts per million. That number gets cited constantly as the safety threshold. What most testing companies never tell you is that the EPA designed those limits specifically for public municipal water systems, not private wells.
Using municipal standards to evaluate well water gives you an incomplete picture. At ETR, we look at nitrates in private wells differently. When we see nitrate levels at 2 parts per million or above in a private well, we pay close attention. In our experience, that level reliably signals surface water is infiltrating the well.
Where surface water goes, bacteria follows. The data across hundreds of thousands of tests is consistent: as nitrate levels rise in private wells, so do bacteria counts. A 3 ppm nitrate reading paired with elevated coliform is not two mild problems. It is likely one serious structural issue that needs attention before it gets worse. That kind of interpretation requires field experience, not an algorithm built on public water thresholds.
3. Fungi in Well Water Is a Hidden Health Threat the Industry Largely Ignores
Fungi counts in drinking water are not something most labs even offer as a standalone test. The industry has historically focused on bacteria as the primary biological threat, treating fungi as a secondary concern at best. At ETR Laboratories, we started taking fungi seriously because our comprehensive microbiological analysis kept showing us things bacteria counts alone could not explain.
Research published in peer-reviewed journals confirms that fungi can produce mycotoxins in water, which are toxic compounds with real health effects for people exposed over time. Fungi enter wells through the same pathways as other contaminants: unsealed well caps, damaged conduit fittings, insects, and in cases we have personally documented, even rodents. Once inside, certain fungal species including various molds produce these compounds at levels that matter for long-term health.
The connection between fungi and bacteria suppression makes this even more significant. A homeowner with high fungi in their well may have been told for years that their water is safe, based on a low bacteria count, while continuing to drink water with elevated mold and yeast. That homeowner deserves better information. We built our fungi and mold testing capabilities because we believe they do.
4. Wells Near Lakes and Large Wetlands Face a Unique and Often Underestimated Microbial Challenge
When most people think about well contamination, they picture surface water getting in through a damaged cap or compromised casing. Wells near lakes and large wetland areas present a different and more complicated problem. Even a structurally sound well cannot fully escape this one.
When a well is drilled, the casing is designed to block surface water and draw from deep aquifers where microbial content is naturally low. The further down you go, the harder it is for bacteria, mold, and other organisms to survive. In most situations, a properly drilled well tapping a deep clean aquifer consistently produces water with very low microbial activity.
Large bodies of water like lakes change that equation significantly. The sheer volume of surface water exerts pressure on the surrounding geology over time, contaminating upper aquifer layers with microbial content. Even aquifers that would otherwise be clean can become compromised when they sit beneath or adjacent to a large lake. Great care must go into well depth and placement during drilling. Otherwise, a lake property well often taps into an aquifer that is at least partially influenced by that surface water body.
The data is clear: we see microbial issues at a significantly higher rate on lake and wetland properties than in comparable homes without large water bodies nearby. We also see a frustrating pattern where clients disinfect their well successfully, only to find bacteria counts return to unsafe levels within a month or two. That cycle strongly indicates the contamination source is geological, not structural, and that disinfection alone is not a long-term fix. For lake and wetland property owners, we strongly recommend comprehensive microbial testing and a direct conversation with our team about UV disinfection or chemical injection systems.
5. Stagnant Water in Vacant Homes Is One of the Most Misunderstood Results in Real Estate Transactions
This scenario comes up constantly in home purchase situations and causes a tremendous amount of unnecessary panic. A homebuyer orders a water test on a property with a private well. Results come back showing elevated bacteria counts, sometimes even coliform present. Everyone gets concerned: buyers are worried, sellers are defensive, and agents are scrambling.
Then we ask one simple question: has this home been vacant for an extended period of time? The answer is almost always yes.
When a home is occupied and the well is in regular use, water is constantly drawn out and replenished from deep aquifers where microbial content is naturally very low. That constant flow dilutes any microbial activity that would otherwise accumulate. A healthy active well in regular use will typically produce a standard plate count bacteria level well under 500 colony-forming units per milliliter, which is the generally accepted threshold for concern.
When a home sits vacant for months, the water in the well and plumbing becomes stagnant. Microbial content that would normally be flushed out accumulates instead. The results can look alarming on paper: elevated bacteria counts, occasionally even coliform detected, even when nothing is structurally wrong with the well.
We identify this situation by looking at the full picture rather than reacting to a single number. If bacteria counts are elevated but nitrates are absent, there are no other indicators of surface water infiltration, and the well cap is in good condition, stagnant water from vacancy is almost always the explanation. A single elevated bacteria result from a vacant home should never be the reason a sale falls apart. Context is everything, and context is exactly what you get when you work with a lab that talks you through what your results actually mean.
6. Road Salt Is Quietly Contaminating Wells Across the Northern United States
For homeowners in northern states where roads are treated with salt each winter, there is a contamination source affecting private wells that rarely gets discussed. In most cases, it goes completely unidentified without the kind of comprehensive analysis and field experience ETR Laboratories has developed over decades.
Here is what we started noticing years ago. Clients would come to us complaining about repetitive pipe corrosion, hot water tank deterioration, fixtures clogging faster than expected, and in some cases skin dryness and irritation from their water. When we looked at their test results, the answer kept appearing in the same place: elevated calcium levels in wells located near roads that receive heavy winter salt application.
Road salt is one of the most water-soluble substances that exists. Research published in Environmental Science and Technology and by the U.S. Geological Survey confirms that when salt is applied to roads year after year, it does not simply wash away. It infiltrates the soil, reaches the groundwater, and finds its way into the aquifers that feed private wells. There is no EPA maximum contaminant level for calcium, which means this problem can go completely undetected by labs that only check results against regulatory thresholds.
At ETR, we started identifying calcium patterns pointing directly to road salt contamination long before clients ever connected their water problems to the road outside their house. In our experience, calcium levels above 30 parts per million in a well warrant attention. At 70 parts per million or above, road salt contamination moves to the top of our list of suspected causes. We have tested wells with calcium readings over 100 parts per million in heavily salted road corridors, and in those cases the effects on plumbing and fixtures were significant and costly.
Through our in-field well inspection work, we identified a structural solution that produces remarkable results: a Jaswell seal. A Jaswell seal extends the casing of an existing well deeper into the ground. When casing is limited to the upper portion of a well, the system still draws from aquifers at relatively shallow depths where road salt concentration is higher. By extending the casing, you seal off those upper contaminated aquifer layers and force the well to draw exclusively from deeper, cleaner water sources where road salt has not penetrated.
We have documented cases where clients with calcium levels over 100 parts per million achieved reductions of 75 percent or more after having a Jaswell seal installed. A Jaswell seal typically costs between $2,000 and $2,500. When you consider the cost of replacing corroded pipes, hot water tanks, and damaged fixtures over the years, that investment pays for itself quickly. More importantly, it is a permanent structural fix rather than a filtration solution that requires ongoing maintenance.
That said, a Jaswell seal is not always the right answer. Before recommending any structural intervention, we look at the full picture of a client’s results. If we see elevated calcium alongside elevated nitrates, that points us in a different direction. Nitrates signal surface water infiltration, which may mean the problem is closer to the top of the well. Getting the right diagnosis requires someone who has actually visited the well and assessed the slope of the surrounding land and the proximity to the road. See what to expect from a well inspection.
Why This All Matters When Choosing a Water Testing Lab
Companies that rely on algorithms to analyze your water results often miss the nuances that matter most. An algorithm built on EPA public water thresholds cannot account for the fact that a 2 parts per million nitrate reading means something different in a private well than it does in a municipal system. A color-coded score cannot tell you that your low bacteria count may be suppressed by mold rather than reflecting genuinely clean water. Automation is efficient, but it is not curious, and water quality requires curiosity.
Maintaining an ongoing dialogue with our clients is not a customer service feature at ETR Laboratories. It is a scientific necessity. The insights in this article did not come from processing samples in isolation. They came from listening to clients describe their water, asking follow-up questions, running additional tests, and paying close attention to what the data told us across hundreds of thousands of samples over many years. That feedback loop between lab analysis and real-world client experience is how you learn things no algorithm will surface on its own.
Water quality research is ongoing at ETR, and the more comprehensive our analysis becomes, the more we continue to learn. If you have questions about your water that a data sheet has never fully answered, that is exactly the kind of conversation we want to have. Give us a call at (800) 344-9977.
