Secondary disinfection provides an essential residual that prevents the regrowth of microorganisms in the distribution network. Chlorine, chloramines, and chlorine dioxide are commonly used as secondary disinfectants. However, chloramine is the most commonly used secondary disinfectant. Chloramine is not virucidal and is only slightly effective in killing Giardia cysts.

When water passes through various stages of purification, it must be disinfected to the extent necessary, depending on its intended use. For example, drinking water, after purification and removal of suspended and dissolved substances, must be free from any microbial contamination and not pose any health and safety risk to the consumer. The destruction or inactivation of microscopic organisms and pathogenic microorganisms is known as water disinfection.

This device uses reverse osmosis to remove about 95 to 99 percent of the chemicals and salts in the water and is easily installed under the sink with a separate drinking water tap. The water filter only removes large particles and impurities in the water, such as mud, sand, and rust from pipes, while reverse osmosis, by using a semi-permeable membrane, not only removes particles mixed in the water, but also all chemicals and microbial, viral, and other contaminants dissolved in the water.

The steel industry uses large amounts of water. However, very little is consumed, as most of the water is reused or returned to the source. Water is used not only in cooling operations, but also in other processes such as scale removal and dust cleaning.

pH measurement is one of the most important and common tests in water chemistry. Almost every step in water supply and wastewater treatment (e.g., acid-base neutralization, water softening, sedimentation, coagulation, disinfection, and corrosion control) depends on pH. pH is used in the measurement of alkalinity and carbon dioxide and many other acid-base equilibria. At a given temperature, the intensity of the acidic or basic activity of a solution is indicated by pH, or hydrogen ion activity.

Before entering the water supply network, the contaminants in drinking water contain high amounts of minerals and metals as well as pathogenic microorganisms, most of which are destroyed in various ways. Performing various purification strategies does not have much effect on the pathogenic bacteria present in the water, and for this reason, various methods, equipment, and materials are used in the chemical purification stage to destroy these bacteria.