For reverse osmosis to be effective, what must be true about the feed water?

For reverse osmosis to be effective, the feed water must be under high pressure. This is because reverse osmosis works by pushing water through a semi-permeable membrane that blocks contaminants. The pressure is necessary to overcome the natural osmotic pressure of the solution, allowing clean water to pass through the membrane while leaving impurities behind. Higher pressure increases the flow rate of treated water and improves the efficiency of contaminant removal, which is essential for producing high-quality water.

In contrast, while temperature can influence the process, it is not a primary requirement for effectiveness. High levels of contaminants can reduce the system's performance and lifespan but are not a prerequisite. Low turbidity is beneficial, as clearer water generally improves the efficiency of the reverse osmosis process, but it is not essential for effectiveness. The key factor is that the feed water must be under high pressure to achieve optimal separation of contaminants from water.