Other
Reverse Osmosis and Osmotic Pressure What They Are
This site gives a good explanation of osmosis and reverse osmosis. Also includes a scientific diagram of the process.
Other
Fundamentals of Reverse Osmosis
This site provides a basic definition of reverse osmosis, with a bit of a slant on why water pretreatment is important.
Curated OER
Reverse Osmosis and Osmotic Pressure What They Are
This site gives a good explanation of osmosis and reverse osmosis. Also includes a scientific diagram of the process.