eli5 what exactly is reverse osmosis?

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I recently installed a reverse osmosis water filter in my home. Based on my home testing equipment it does a really great job of removing unwanted substances in my water. What is the process of reverse osmosis and how is it different than, say, a britta filter that you pour water through?

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2 Answers

Anonymous 0 Comments

A Britta filter typically uses charcoal, which has a lot of little nanoscopic pits in the charcoal molecule to trap contaminants and allow water to pass through.

Reverse osmosis uses a semipermeable membrane designed to filter materials that you don’t want through process of force.

Typically, when water with solute encounters water without solute, the 2 will mix as solute typically moves towards an area of low concentration. If you place a semipermeable membrane between a solution of high solute and a solution of low solute, water from the low solute side will flow through the semipermeable membrane towards the side of high solute. This is called osmotic pressure. Where the area of high solute litteral pulls in water from the area of Lower solute. Of course, this is not what you want. So, to counter that osmotic pressure, you apply hydrostatic pressure to the area of high solute. This forces water through the semipermeable membrane, trapping the unwanted solute at the membrane.

The major difference between a reverse osmosis filter compared to a very fine filter is that the reverse osmosis membrane is submerged in water on both sides, while a standard filter is only submerged in water on one side.

Anonymous 0 Comments

Just a fancy filter that works by passing water though a special tube instead of special sand. Brita filters neutralize impurities using activated carbon, which is a type of filtration called ‘**AD**sorbtion’.

Reverse osmosis works well because the holes in the tube are VERY SMALL. Anything bigger than an H2O molecule can’t pass through the filter. This is a different type of filtration called ‘occlusion’. However, you need to pressure the water up to make it go through the filter.

**AB**sorbtion, on the other hand, is a type of filtration where the impurity is brought into the body of the filter, like a sponge.