The size of Reverse Osmosis (RO) plants can vary significantly depending on various factors such as the intended application, water demand, and available space. Generally, RO plants are sized based on their production capacity, which is typically measured in Gallons Per Day (GPD). Here is an overview of the minimum to maximum range for RO plant sizes in GPD:

1. Minimum Size: The smallest RO plants typically start around 50 GPD to 100 GPD. These smaller systems are often used for residential purposes, such as providing purified drinking water for a single household or small office.

2. Medium Size: RO plants in the mid-range typically range from 500 GPD to 10,000 GPD. These medium-sized systems are commonly employed in commercial settings like restaurants, small businesses, schools, or hospitals where there is a moderate demand for purified water.

3. Large Size: Larger RO plants can range from 10,000 GPD to several hundred thousand GPD or even millions of GPD for industrial-scale applications. These large-scale systems are utilized in industries such as pharmaceuticals, food and beverage production, power plants, and municipal water treatment facilities where there is a substantial demand for purified water.

4. Maximum Size: The upper limit for RO plant size is determined by factors such as available space, budget, and specific project requirements. Industrial-scale RO plants can be customized to produce millions of gallons of purified water per day to meet the needs of large-scale operations.

In summary, the size of an RO plant can vary widely, ranging from small residential systems to large-scale industrial installations, with capacities spanning from as low as 50 GPD to several million GPD, depending on the application and demand.