Raw water intakes draw water from various specified levels in rivers, lakes, or reservoirs behind dams. In order to protect the pumps and remove large objects from the water before it enters the pumping station, strainers are usually installed in the intake structure. Aeration is a process unit that removes gases and volatile organic compounds that cause taste and odor problems in the water supply system.

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.

Aeration has little effect on taste and odor removal. Most of the compounds that cause taste and odor have high solubility in water. Therefore, except in a few cases, aeration is usually less effective in removing taste and odor than other methods such as chemical oxidation or adsorption.

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.

Softening processes are used to reduce water hardness. Using chemicals, water hardness undergoes chemical reactions and precipitates. As a result, water hardness is reduced. Water hardness is due to the presence of carbonates, sulfates, chlorides, and nitrates of the metals calcium, magnesium, iron, and aluminum.

همه ی منابع آب دارای طیف وسیعی از ناخالصی های آلی و غیر آلی هستند. تصفیه ی آب عبارت از حذف اجزای نامطلوب از آب و سپس دفع آن ها به آسان ترین و مطمئن ترین روش است. برای رسیدن به این هدف، از فرآیندهای مختلف تصفیه که از پدیده های فیزیکی و شیمیایی مختلفی برای حذف یا کاهش اجزای نامطلوب از آب بهره می برند، استفاده می شود. انتخاب فرآیندهای تصفیه یکی از کلیدهای عملکرد موفق هر تصفیه خانه ی آب است.

چون هر منبع آب از لحاظ ترکیب شیمیایی منحصر به فرد است، برای به دست آوردن پارامترهای طراحی و بهره برداری فرآیندهای تصفیه، اغلب انجام مطالعات تصفیه پذیری ضروری است. چنین مطالعاتی به ویژه در جاهایی که تصفیه خانه ی جدید پیشنهاد می شود، از اهمیت ویژه ای برخوردار است.