We have already discussed the main quality indicators of the drinking water in our previous article. Today we will talk more about how to determine the water quality indicators at home using measuring devices such as TDS or salt meter, pH meter and ORP meter. In this article we will explain what are these devices, why they are useful as well as what other methods are suitable for evaluating water quality indicators at home.
What is a TDS meter?
TDS is the total amount of dissolved solids in the form of ions: calcium, magnesium, sodium, potassium, carbonates, sulfates, chlorides, heavy metal ions, individual organic ions, etc. A TDS meter is called a salt meter because it measures the total amount of salts in a solution. It is also called a conductometer because it initially measures the electrical conductivity of the solution (the fewer minerals, the lower the electrical conductivity) and then converts it to salt indicators (ppm (parts per million) and mg/l).
Sellers of household appliances often say that a TDS meter can determine the water quality. However, it is important to know that the total amount of salts in the water is only one of more than 70 water quality indicators which by itself does not say much about the overall quality of the water.
According to the World Health Organization (WHO) drinking water quality guidelines, drinking water with a TDS less than 600 mg/l is considered adequate. If the TDS level exceeds 1000 mg/l, changes the taste of the water. What is more, a high TDS level promotes corrosive processes.
What is a pH meter?
The pH meter is designed for determining the hydrogen index or hydrogen ion concentration which characterizes the acid-base balance in solutions. A pH meter measures the electromotive force (EMF) of a solution and converts it into a pH indicator. The pH scale consists of 14 units (0-14), where units 0-7 indicate an acidic environment, unit 7 indicate a neutral environment but units 7-14 indicate an alkaline environment. Surface water is characterized by a pH value from 6 to 9 while the permissible pH value for drinking water is from 6.5 to 8.5.
In domestic conditions the pH meter is useful for owners of aquariums and swimming pools. In both cases it is important to maintain a certain pH level (adding special reagents if necessary). Also alkaline water supporters often buy this device. When using a pH meter at home it should be noted that this device requires constant calibration and, if the settings are not made correctly, it may show inappropriate values.
What is an ORP meter?
The oxidation-reduction indicator or “Redox potential of water” indicator has been used in chemical technology for many years to assess the presence of substances in water or solutions that are capable of oxidizing and reducing each other.
This indicator is not officially used in the assessment of drinking water quality but after several publications about redox potential the supporters of alternative medicine began to use it for determining “living” and “dead” water.
As a matter of fact, an OPV meter is a voltmeter that measures the electromotive force produced by electrons moving from a reducing agent to an oxidizing agent in a liquid medium.
Test strips for determining water quality
This express testing method is based on semi-quantitative determination of substances. A certain amount of reagent is applied to the paper which changes its color when it comes into contact with water. The paper strip is compared to a multi-colored comparison scale that determines the concentration range of the substance. With this method it is possible to approximately determine water hardness, total salinity, aluminum, arsenic, ammonium, chlorine, iron, hydrogen sulfide, copper, nickel, cobalt, etc. concentrations.
Read also: What does the water analysis say?