The set of structures in which water is treated so that it becomes suitable for human consumption is called potable water treatment station (often abbreviated as ETAP), water purification station (EPA) or potable water treatment plant (PTAP). These plants can be conventional or compact.

The plant units vary according to its type, the state of the raw water to be treated or the population served. The units are collection, coagulation, flocculation, sedimentation, filtration, chlorination or disinfection and finally storage and its respective distribution.

There are different technologies to make water drinkable, but they must all comply with the same principles:[1]​.

If there is no storage volume for potable water, the plant capacity must be greater than the maximum daily demand in the design period. Furthermore, a treatment plant must operate continuously, even with some of its components undergoing maintenance; That is why at least two units are necessary for each plant process.

A combination of technologies can also be used, and in each of the named technologies it is possible to have other processes that may be specifically necessary to remove certain contamination.