Monday, October 1, 2018

Water Test Results Tell a Story

The quality and safety of private or domestic wells are not regulated under Federal or, in most cases, state law. In Virginia only construction of wells is regulated, and the absence of bacteria at well completion is the only water quality test required. Individual homeowners are solely responsible for maintaining their domestic well systems and for any routine water-quality monitoring that may take place. However, private well owners often lack a basic understanding of groundwater and wells and the mechanical components in private water systems and are often unaware of common issues with wells, and lack access to objective information and a framework for understanding their water quality.

Because private drinking water wells serves 1.7 million, or 22% of its population, Virginia has taken steps to assist private well owners monitor, understand and maintain their wells. The Virginia Household Water Quality Program (VAHWQP) was created by the Virginia Cooperative Extension to provide affordable water testing and education about private water wells to residents of the Commonwealth. Volunteers and Extension Agents hold drinking water clinics and other outreach programs. During the water clinics in 2017 -2,178 samples analyzed in 87 counties. I am one of the volunteers and help run the water clinics in Prince William and Fairfax Counties.

Over the years I have looked at a lot of well water results and helped well owners understand their water. Water quality is driven by geology, well construction and condition, nearby sources of contamination, and, within the home, water treatment devices and composition of plumbing materials. Though there are anomalies, water tells me a story. Though that was not always true, years ago even with graduate degrees and a working knowledge of water contamination I was not confident about interpreting groundwater analysis especially in unfamiliar geology.

The other day someone emailed me their water test results. They had purchased a WaterCheck with Pesticides package from National Testing Laboratories. This is an informational test packages targeted to be an affordable option for consumers. The WaterCheck with Pesticide covers 15 heavy metals, 5 inorganic chemicals, 5 physical factors, 4 trihalo methanes, 43 volatile organic chemicals (solvents), and 20 pesticides, herbicides and PCB’s. The Minimum Detection Levels, which are the lowest levels at which the laboratory detects that contaminant are below the levels established by the Safe Drinking Water Act, so this relatively affordable test will serve as a broad screen of drinking water.

The WaterCheck with Pesticides test results showed detectable levels of copper, iron, silica, sodium, zinc, alkalinity as CaCO3, nitrate, chloroform, THMs, turbidity, total dissolved solids, . All other substance tested for were non-detect this included hardness, calcium, manganese- things that are common in Prince William County groundwater.

In order to determine if there is a problem, water test results should be compared to a standard. The usual standard is the U.S.EPA Safe Drinking Water Act (SDWA) limits. Though private wells do not fall under the regulatory authority of the U.S. Environmental Protection Agency (EPA) or the Safe Drinking Water Act, the SDWA has primary and secondary drinking water standards that can be used for comparison. Primary standards are ones that can impact health. Secondary standards impact taste or the perceived quality of the water.

The EPA primary contaminants found to be present were nitrate, copper, and total THMs. All these substances were below the EPA SDWA standard called the Maximum Contaminant Level (MCL). The presence of copper at 0.227 mg/L less than a fifth of the MCL with a neutral water pH spoke of copper pipes. So we know this home was built before 1979. Over time, even neutral water will wear away the pipes. The pH of the water and copper levels should be monitored regularly. The nitrate level was 6.1 mg/L with an SDWA MCL of 10 mg/L.

Nitrate in groundwater can come from septic systems and livestock facilities, fertilized cropland, golf courses, lawns, and gardens, or even naturally occurring sources of nitrogen. This level of nitrate is most likely from septic systems that are too close together. If a property has 3 or more acres you do not typically see this level of nitrate without E. coli being present. It turns out that this house sits on only one acre.

The total THMs was 0.003 mg/L with a SDWA MCL of o.80 mg/L. Potential sources of THMs to drinking water wells include the discharge of chlorinated drinking water and wastewater that may be intentional or inadvertent also, with the chloroform it can simply be a residual for a recent chlorine shocking of the well. It turns out that a couple of months before the homeowner had chlorine shocked the well to treat a finding of coliform bacteria. No E. coli had been present. Over time the THMs and chloroform should disappear.

The sodium level was 126 mg/L and chloride was 42. mg/L. The sodium was above the secondary standard for sodium of 20 mg/L. Also, there was no hardness detected. This level of sodium, an absence of hardness and a 6.8 pH says water softener. Though road salt and salt water infiltration can both raise sodium levels. The question is does this home need a water softener? With extremely hard water, a softener would leave a bit of hardness. Most people prefer some hardness in their water so modern softeners are designed to be adjustable and leave a little hardness. Water softeners are often used in combination with neutralizers to remove some hardness. When I asked there was no neutralizer on this system. Water softeners can also remove some iron and manganese. The residual iron level is 0.021 mg/L with a SDWA secondary recommended MCL of 0.3 mg/L. It could be that the water was installed to control iron, but when I asked the homeowner, she stated that the softener was installed to control the rust slime in the back of the toilet.

That rust colored slime is iron bacteria and would not be controlled by a water softener. A water softener can make it worse. However, the homeowner confirmed that the rust colored slim in the back of the toilet was not helped by the softener. However, the recent installation of a UV light to control coliform bacteria that was not eliminated by the shock chlorination had eliminated the rust colored slime. This is interesting, iron and sulfur bacteria are more resistant than other bacteria because they occur in thick layers and are by the slime they secrete. This is interesting observation on the part of the homeowner. However; the UV light was purchased after the chlorine shocking of the well failed to eliminate the coliform bacteria. It is just as likely that the recent chlorine shocking of the well pushed back the iron bacteria. This is a data point to be verified and filed. UV light is a powerful disinfectant that can kill bacteria, viruses and parasites, provided the water is perfectly cleear, low in minerals, and free of iron and sediment. This is why UV systems are often installed after a water softener or filtration system. To reduce the sodium, the homeowner might dial back the water softener or replace it with an appropriate filter.

The other findings were silica, zinc, total dissolved solids, and turbidity that were all within the normal amounts seen in the county and less than the SDWA secondary MCL. These substances are naturally present at these levels in our geology and have not impaired the water taste or quality.

Overall, their water is pretty good. The sodium content of the water is too high and might impact the taste. The UV light is working and the homeowner might want to test the raw water (before any treatment) so see if the water softener can be replaced with a filter to eliminate the sodium problem.

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