Access to quality drinking water is a problem for billions of people across the planet. Inadequate santitation is the leading cause of water contiamination worldwide. As a result, at least 2.5 billion people lack access to decent water. This is one of the reasons that diarrheal disease kills more children under five years old than tuberculosis, HIV and malaria combined. Even in areas where santitation is available, not all water is pure enough to consume. In the United States, nearly 44% of all streams, 64% of all lacks and 30% of bays and estuaries have water that is clean and pure enough for fishing and swimming. Water quality is everyone’s problem. One way to measure the purety of a sample of water is to use a water conductivity monitor.
A water conductivity monitor measures how much electrical current can be passed through the water sample. This can be an important way to check water because the more pure it is, the lower is connectivity will be. This is because it is not the water molecules themselves that carry the current but other subtances present in the water. For example, when table salt (sodium chloride) is added to water, it breaks apart into its sodium (Na+) and chloride (Cl-) ions. This solution carries the current. Therefore water testing kits really test the amounts of salts (there are different kinds of salts) that are present in any water sample.
Currently, there is no guideline for how to match up a water level’s conductivity with its quality but if a water conductivity monitor is used regularly, if changes are detected, they can be an indication that the water source has been contaminated. Rising conductivity can be caused by a number of factors.
Factors that Influence Water Conductivity.
- Presence of pollutants. Increased conductivity can indicate the presense of chemicals and other pollutants from water treatment facilities, runoff water from roads and streets and agricultural waste products. All of this can change throughout the year and is very much impacted by the season. For urban runoff, if the areas receives lot of snow during the winter, this may greatly increase the amount of chemicals that are passed into nearby water sources. Agricultural runoff changes throughout the year and does add a lot of a variety of salts, pesticides and other pollutants to the local water sources. This can include organic matter.
- Interaction of the water and the atmosphere. For most areas in the United States, this is not an issue as the atmosphere does not contribute a lot of ions to local water sources. In coastal regions near the Pacific and Atlantic Oceans, however, more salts are added to the air and are moved to local water sourced when it rains. This can increase the conductibvity of the water.
- Evaporation can make a difference. Some water is exposed and thus suseptible to evaporation. This increases the water’s salinity and corresponding conductivity. This is more of a problem for water reservoirs in hot and dry climates such as those found in the American west.
- Bacteria can also play a role. Bacteria can increase the acidity of water in a reservoir and therefore increase its salinity and conductivity. This is because as they break down, they often release carbon dioxide and that lowers the pH of the water.
While using a water conductivity monitor once will not tell you much about the water quality. Using a water conductivity monitor as part of an analysis of water quality parameters that is done regularly, can give you an idea of what is happening with the water quality over time. Knowing the baseline at different times of the year, if you are measuring water that is impacted by agricultural runoff, it will vary depending on the season and weather, can help the detection of new and potentially dangerous contaminants in the water supply.
The goal is then to make sure a water source or sample’s conductivity levels remain consistent with what they should be given the local environment, economy and climate. What makes sense in Nevada will not make sense in New York or Minnesota, for example.
