In daily life, tap water is the most common type of drinking water. The residual chlorine in tap water refers to the remaining chlorine-based disinfectant added by water plants before water is discharged, which is known as residual chlorine. However, the residual chlorine level must be well controlled to ensure that the residual chlorine content at the pipe network terminals in contact with users meets the standard.
So How Exactly Should we Understand Residual Chlorine in tap Water?
In fact, when you smell a chlorine odor in tap water, it indicates that the water has been disinfected. It also means that pathogenic microorganisms in the water have been eliminated. It should be noted that the purpose of adding disinfectants to water is to kill harmful substances such as microorganisms in the water, preventing them from infecting the human body through water as a medium. Nevertheless, it is important to note that disinfectants will react with organic matter and other substances in the water, thereby producing disinfection by-products that are harmful to human health. There are many types of such by-products, including chlorite and trihalomethanes.
For this reason, we must control the dosage of disinfectants to avoid the formation of harmful disinfection by-products. Multiple factors affect the generation of disinfection by-products, which can be mainly divided into the following categories:
1.The concentration and type of precursors affect disinfection efficacy. For example, surface water is often severely polluted with a wide variety of contaminants, so the types and concentrations of by-products generated through oxidation with chlorine are much higher than those in groundwater.
2.Factors such as pH value and water temperature affect the formation of disinfection by-products to varying degrees. Higher levels of these substances will lead to increased formation of trihalomethanes in water.
3.In addition, chlorine dosage, disinfection procedures, residual chlorine level, seasons and other factors all affect the production of disinfection by-products.
The specific content cannot be determined simply by smell or sight; in such cases, the RCl900 Online Residual Chlorine Analyzer is used for detection. It should be emphasized that the working principle of this residual chlorine detector is the same as that of the RCl90 Online Total Residual Chlorine Analyzer used for Medical Wastewater Online Monitoring—they only differ in the specific indicators detected, i.e., residual chlorine and total residual chlorine respectively.
The standards for detection indicators vary with different disinfectants, so users need to understand the corresponding residual disinfectant standards based on their actual situations. For instance, when chlorine gas is used for disinfection, the residual chlorine in water shall not be lower than 0.3 mg/L nor higher than 0.5 mg/L.
