Drinking water generally comes from four types of water sources: river water, reservoir and lake water, well water, and deep spring water. Relatively speaking, deep underground spring water is an ideal source for drinking water. Its turbidity and microbial indicators are relatively low, and it is rich in mineral content. (However, if heavy metal contamination is present, its use is not recommended.)

The taste of a food product determines its success or failure and shapes the future of the enterprise. Therefore, most food processing companies—such as beverage factories, juice manufacturers, bakery and pastry producers, dairy product enterprises, and distilleries—have strict requirements for process water. This is especially true for liquor production enterprises.

The commonly used process in direct drinking water treatment systems is the reverse osmosis process, which employs ultraviolet radiation for disinfection to prevent secondary contamination of the water quality.

There are numerous industries that use pure water equipment in industrial applications, such as: boiler feed water, cooling tower make-up water, electroplating plants, electronics and battery manufacturing, metallurgy, chemical production, cement plants, coal-fired power plants, nuclear power plants, and the textile dyeing industry, among others. Depending on the specific production process, the quality requirements for process water vary. However, in general, the process water used in industry is mostly softened water, pure water, or even ultrapure water.