What methods are used to test water purity?

Water purity is typically tested using methods such as physical examination, chemical analysis, and microbiological tests.

Physical examination is one of the simplest methods to test water purity. This involves assessing the water's appearance, odour, and taste. Clear, odourless, and tasteless water is generally considered pure. However, this method is not foolproof as some contaminants are colourless, odourless, and tasteless.

Chemical analysis is a more reliable method. It involves testing the water for the presence of harmful chemicals such as lead, arsenic, and mercury. This is usually done in a laboratory using sophisticated equipment. The water sample is subjected to various chemical reactions, and the results are analysed to determine the presence and concentration of different chemicals. For instance, the presence of lead can be detected by adding sodium rhodizonate to the water sample. If lead is present, the solution will turn red.

Microbiological tests are used to detect the presence of harmful microorganisms in the water. These include bacteria, viruses, and parasites that can cause diseases such as cholera, typhoid, and dysentery. The water sample is cultured in a laboratory, and the growth of microorganisms is monitored. If harmful microorganisms are detected, the water is considered impure.

In addition to these, there are also other methods such as the use of conductivity meters to measure the total dissolved solids (TDS) in the water. High TDS levels indicate the presence of impurities. Similarly, pH meters are used to measure the acidity or alkalinity of the water. Pure water has a neutral pH of 7. Any deviation from this indicates the presence of impurities.

In conclusion, testing water purity involves a combination of physical examination, chemical analysis, and microbiological tests. These methods help ensure that the water we consume is safe and free from harmful contaminants.