Mar 31, 2017 · The bottom line. When you have smaller flows, like 10 or 20 GPM, your costs can be under $100,000 on a typical front-end system. A smaller high-end system you might use for a power plant for 100 to 200 GPM, might be $450,000, whereas a commercial version might be $250,000 for 150 to 200 GPM.