Which of the following describes the chemical feed pump's function?

The function of a chemical feed pump is primarily to inject treatment chemicals into a water system. This process is essential for various applications within water treatment, such as disinfection, pH adjustment, nutrient addition, or other necessary chemical treatments to maintain water quality. The pump ensures that the correct dosage of chemicals is introduced into the water efficiently and consistently, helping to achieve the desired water characteristics.

The other choices provided do not align with the role of a chemical feed pump. Softening water refers to the process of reducing hardness, which is typically achieved through other means, such as ion exchange or reverse osmosis, rather than through chemical injection alone. Controlling temperature falls under different equipment and processes, like heaters or chillers, rather than the function of a pump designed for chemicals. Measuring water flow is done using flow meters or similar devices, again outside the scope of a chemical feed pump's purpose.