Drinking water treatment can be accomplished either in centralized water treatment facilities or at individual homes or businesses.

In large cities, water treatment facilities treat large volumes of water intended for residential, business, and industrial uses. While the technologies may be fairly standard, such a system may have a host of infrastructure, such as filters, chemical storage, pumps, piping, valves, electrical equipment, and instrumentation. Initial cost is typically high. They may also require water source development, construction of infrastructure, and adoption of a system to distribute the water to consumers. In most developing countries, these systems may be financially out of reach for smaller or poorer communities.

Smaller communities can reduce costs by using pre-engineered “package plants.” Most package plants designed to provide water filtration are typically not equipped for disinfection, corrosion control, or adsorption of organic contaminants by granular activated carbon.

Where community treatment plants are not available or are not trustworthy, water treatment becomes a more individual choice. Point-of-use and point-of-entry water treatment systems are widely used in individual homes and businesses. In poorer areas, where there are significant deficiencies in financial resources and technical skills, point-of-use and point-of-entry may be the only treatment options. Point-of-use systems are typically installed where water is used for drinking and cooking, such as on the kitchen faucet. Point-of-entry systems, in contrast, are installed where water enters a building and treat all water to be used for any purpose at that location. Systems exist that can treat a number of contaminants including primarily aesthetic concerns (e.g., color and odor).