By Marianne R. Metzger
Spring is a time known for rebirth and regrowth. It is also an important time of year that can greatly affect the quality of not only surface water but also groundwater sources. There are a variety of reasons, but the most obvious being the changes in weather. Depending on where you are located in the world, springtime brings those famous rain showers and the warming of weather, which promotes snow melt. This snow melt and seasonal rain runoff into surface waters such as streams, lakes and rivers. This additional water also soaks into the ground to recharge aquifers. All the extra water that comes as a result of spring weather can pick up contaminants, such as bacteria, nitrate from fertilization or sodium and chloride from areas that use road salts in the winter months. The water dissolves these contaminants and can sweep them into surface water supplies directly or can infiltrate shallow or accessible aquifers underground. This makes springtime an ideal time to test private wells, because they are most vulnerable to contamination in times of heavy precipitation.
Wells that are underwater due to excessive rains could potentially be contaminated with bacteria and other pollutants. If a well has been flooded, it should be considered unsafe to drink. The biggest and first concern is bacteria. The well should be disinfected, preferably by a professional well contractor who is familiar with proper disinfection procedures. Once the well has been disinfected, it’s a good idea to test for bacteria and other potential contaminants. If the bacteria test is positive after disinfection, sufficient disinfectant may not have been added. Depending on the quality of water, additional chlorine may be needed if iron, manganese and hydrogen sulfide are present, as these contaminants tend to use up the chlorine where demand exceeds free available chlorine. If the proper amount of chlorine was added, the water source may be under the influence of surface water, which means a greater potential for bacterial contamination could result, especially when rainfall is significant. If this is the case, a more permanent means of disinfection is recommended.
It’s important to determine what is approved by the state health department and what else is in the water before deciding on the best method for disinfection. An excellent choice for permanent disinfection is ultraviolet light because it does not require the addition of chemical disinfectant. There is little maintenance and no ongoing cost for chemicals, making it an attractive option. If the water is naturally hard, however, it may require pretreatment to prevent scale build-up on the quartz sleeve of the UV light. Keeping the sleeve clean is crucial to ensuring full disinfection. Additional treatment can add to the initial costs in equipment and ongoing salt purchase for those needing softeners. Continuous feed of chlorine can also provide continuous protection and may help in reducing other contaminants like iron, manganese and hydrogen sulfide. It may produce byproducts that would then have to be removed with additional treatment.
Other methods of disinfection can include ozone and other chemical disinfectants like hydrogen peroxide or chlorine dioxide. An analysis of the water will help make the most informed decision about water treatment possibilities. Even if a well does not become flooded, spring rains can still affect the quality of the water. If there is a problem with the water being discolored or muddy after a heavy rain, surface water may be affected from an improper cap or a crack in the casing. A well contractor should be consulted. Testing will confirm if there is a bacteriological or chemical risk. In addition to the microbiological concerns from rain and snow melt, there are other contaminants that can be of concern. It’s a good time of year to get a baseline of water quality.
Excessive amounts of rain can seep into the ground, picking up whatever it can dissolve from soils and rocks it moves through to reach the aquifer; this can cause fluctuations in contaminant levels. This could be the time of year treatment equipment may fail or have problems due to higher contaminant loads resulting in greater capacity needs or more frequent backwashing or regenerations. When considering a water test, think about where the water source is located and what potential pollutants are nearby. If located near a gas station, landfill or parking lot, excessive rains have the potential to wash contaminants like gasoline or other solvents into the water. In this case, testing for volatile organic chemicals should be done. If the water source is in the country, it may be affected by farming contaminants; i.e., fertilizers, pesticides and manure. Fertilizers and manure from animal feed lots can contribute to bacteria and nitrate contamination, so these are common tests to run under these conditions. If pesticides are suspected, it can get complicated, as there are thousands of pesticides and various methods of testing for them. In addition, testing for pesticides employs some very sophisticated methods, which can be costly. If pesticides or herbicides are suspected, it is best to determine what is and has been used to narrow down the testing needed and control costs.
There are various resources available to help determine what should be tested. One of the best is the US Geological Survey (USGS), which can provide useful information on what contaminants may be present. For example, visit http://energy.cr.usgs.gov/radon/rnus.html for a map of potential levels of radon in groundwater. The agency also has an interactive map that allows one to look at arsenic levels by state or even by latitude and longitude: http://nationalatlas.gov/mapmaker?AppCmd=CUSTOM&LayerList=ar&visCats=CAT-hydro#CAT-hydro. There is a lot of information available on the USGS website and it can be narrowed down by state. States typically have agricultural departments that monitor pesticide use, which may also be helpful in pinpointing what has been used in the area. Other sources of information could include regional US EPA offices, university agricultural departments, local health departments and cooperative extension offices.
Many factors can play a role in how contaminants reach aquifers. First, the depth of the well plays a significant role. The shallower a well, the less distance the water will have to travel to contaminate the water supply. Second, the type of soils and geological formations are critical. For example, an area that has sand layer will allow contaminants to travel easier than in a clay layer. The different characteristics of the potential contaminants can play a role, like solubility in water. There are some contaminants that are less soluble in water than others. For example, MTBE (Methyl-tertiary-butyl-ether), a common gasoline additive in the 1990s, is about 30 times more soluble in water than other common gasoline constituents like benzene, toluene, ethyl benzene and xylene. This is a big reason MTBE started to show up in so many water supplies. Finally, the persistence of the contaminant is important. Some contaminants readily break down into less harmful compounds, while others are persistent and can remain in the environment for long periods of time. A great example of this is PCBs, which have been banned in the US since 1979, yet they persist in the environment today. PCBs werewere also present in a variety of additional products, including other electrical equipment, cable insulation, adhesives and tapes, oil-based paint, caulking and plastics.
Water will fluctuate in quality depending on local and regional conditions, both excessive precipitation or drought conditions. Springtime does not always mean high levels of rainfall. In fact, many areas of the world are experiencing drought and drought-like conditions. It’s important to keep in mind that drought conditions also cause contaminant issues. With less water in the aquifer, naturally occurring contaminants can become concentrated and be found at higher levels. Typical contaminants could include arsenic, calcium, magnesium, iron, radon and other radiologicals. Springtime can also mean an increase in real-estate transactions. Depending on state and local requirements, properties with a private well may be subject to water testing requirements, some as simple as a bacteria test. A positive bacteria test during a real-estate transaction can throw closing off track. When dealing with clients involved in these transactions, it’s important to warn of possible pitfalls when doing springtime testing. It’s also a good opportunity for water treatment professionals to offer well owners a final-barrier option against potential contaminants like bacteria.
Springtime is a time of change in weather and in water quality. It is a time of year that contaminant levels may be at their highest, so it is a good time to test and get a baseline of water quality. Although at any time there can be a number of changes in water quality (like taste, odor or color), it is a good idea to investigate the causes by performing some basic tests. These changes may indicate a problem that has gone undetected.
About the author
Marianne R. Metzger currently works for Certified National Analytics (CNA) and Testmywater.info providing a variety of testing services for residential, commercial and government regulatory requirements. Most of her career has been spent working for laboratories, with specialization in water treatment testing. Previously, Metzger was a Sales Engineer for Accent Control Systems, which provides equipment for in-line and handheld analyzers, flow meters and chemical feed pumps to be used in water, wastewater and other fluid applications. She may be reached via email, [email protected]