PH in Drinking Water, What You Need to Know

pH is a value of the acidity or basicity of a solution, and is the negative logarithm of the concentration of H+ in a solution. The pH ranges from 0 to 14, 7 being neutral, less than 7 acid, and greater than 7 basic. It’s one of the most popular parameters in water quality testing as it can reveal whether there are any chemicals and contaminants present in water samples.

There are a few pH testing techniques for water samples: pH strips and papers, pH meters, pH titration, pH sensors, pH indicators, pH loggers, pH electrodes. Each method has its pros and cons and one should select one based on the use case and the level of accuracy and precision needed.

pH strips and papers are the quickest and most cost-effective pH test, and are very common in the field. They do this by using a pH sensitive probe that glows when the pH of the solution changes. This change of color is then plotted to a color map to get the pH of the water sample [1].

The pH meters are, however, more precise and specific than pH strips and papers, and are most often used in the lab and research settings. They attach a pH electrode and a reference electrode to an electrical potential of a solution, and convert it into a pH reading. But pH meters should be calibrated, cleaned and maintained regularly for a good and consistent reading over time [2].

Another pH measurement technique in laboratory and research settings is pH titration. It is the procedure of containing a known amount of a common acid or base to a water sample, and adding that amount of acid/base until the pH of the solution crosses a certain threshold. Endpoint is reached using an indicator, that becomes colorless when the solution is at the pH you want [3].

The pH sensors are another pH measuring instrument which has a lot of popularity as it can be very precise, precise and provide real-time measurements. They generally have a pH sensitive electrode and reference electrode that read the electrical potential of a solution and convert that into a pH value. You have many types of pH sensor like glass, coated wire and solid-state sensors, each has pros and cons [4].

pH indicator is another laboratory and research grade pH instrumentation. They do so with a pH sensitive indicator that lightens and darkens depending on the pH of the solution. The change of colour is then compared to a color chart to calculate the pH of the water. Many indicators (litmus, bromthymol blue, phenolphthalein), which are all a bit different, and are more or less specific, are on the market [5].

Finally, pH is an often-added value to water quality testing as it’s a good indicator of which chemicals and pollutants are found in water samples. There are several pH measurement methods for water samples: pH strips and papers, pH meters, pH titration, pH sensors, pH indicators, pH loggers and pH electrodes. All methods have pros and cons and the method should be selected based on the use case and accuracy/precision required.