What Causes pH in Artesian Water?

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Water drinkers and enthusiasts like to talk about the properties of their drinking water, especially bottled alkaline water, and pH is one of the most important characteristics because of how it directly affects the way water tastes. But before we get to external factors that affect the pH levels in water, it is helpful to revisit what exactly pH is and what it refers to.

What is pH and Alkalinity?

In water, pH stands for 'Power of Hydrogen'. The numerical value of pH is measured and on scale of 0 to 14, and is determined by the molar concentration of hydrogen ions (H+). This is done by taking the negative logarithm of the H+ concentration (-log(H+)). For example, if a solution has a H+ concentration of 10-3 M, the pH of the solution will be -log(10-3), which equals 3. PH is a determined value based on a defined scale, similar to temperature. This means that pH of water is not a parameter that can be measured as a concentration or a quantity. Rather, it is a figure between 0 and 14 defining how acidic or basic a body of water is along a logarithmic scale The lower the number, the more acidic the water is, and the higher the number, the more basic it is, with a pH of 7 considered to be neutral.

The word 'alkaline' or 'alkalinity' is often misused by bottled water brands in their marketing literature. While it relates to the pH levels in drinking water, it more accurately refers to the way levels pH fluctuate in drinking water. So, in other words, alkalinity technically is a measurement of water’s ability to resist changes in pH. The levels of pH in water can be impacted by external factors such as temperature, salinity and rainfall. If a body of water is high in alkalinity, it can limit or minimize the impact on pH when these naturally occurring factors occur. This is why water from unique places like Hawaii are alkaline. Because the rainfall in Hawaii is so consistent and generally created by the evaporation of cleaner water with lower levels of pollution and toxins as it enters the atmosphere, water with naturally occurring high levels of pH tend to taste better and of higher quality compared to other sources of drinking water. The alkalinity of an underground aquifer at the base of a volcano, for example, is increased by carbonate-rich soils (carbonates and bicarbonates) such as calcium-rich limestone, Because of the presence of carbonates, alkalinity is more closely related to hardness, or mineral levels, than to pH.

What Factors Impact the pH of Water?

There are many factors that can affect pH in water, both natural and man-made. Most natural changes occur due to interactions with surrounding rock (particularly carbonate forms) and other materials. pH can also fluctuate with precipitation and wastewater discharge. In addition, CO2 concentrations can influence pH levels. The alkalinity of water also plays an important role in the daily pH levels of a body of water. Photosynthesis, the process in plants that convert sunlight to carbon dioxide, by algae and plants uses hydrogen, thus increasing pH levels. Additionally, respiration and decomposition can lower pH levels. Most bodies of water are able to restrict these changes due to their alkalinity, so small fluctuations are quickly 'corrected' and may be difficult to detect with any degree of accuracy.

For the average water drinker who is primary interested in taste, this means that higher levels of pH, especially naturally occurring pH, lead to great tasting water.

Photo by KOBU Agency on Unsplash

by Steve Jortsman