Blue Spot Water

How Does Reverse Osmosis Work?

Reverse osmosis (RO) is one of the most effective ways to clean water of unwanted particles and impurities. It is a process that can be best understood by first looking at how water becomes impure.

When water falls to Earth as rain, it is in a clean and pure state, free of particles or impurities. However, as it descends, it picks up dust and other substances suspended in the air. Once it hits the ground, it flows past rocks, minerals, pollutants, and waste from both humans and animals. All these elements dissolve into the water, making it either better or worse for human consumption.

The presence of these dissolved particles makes the water "heavy." To measure this, we use a TDS (Total Dissolved Solids) reading. The higher the TDS number, the more particles are in the water; a lower number means the water is purer.

One of the many reasons for removing these particles is that dissolved solids in water make it a good conductor of electricity. If these particles are removed, the water can no longer conduct electricity. This is why highly purified water can be used to safely pressure wash power lines without the risk of electrocution. To get water free from dissolved solids, reverse osmosis is used.

The Mechanism of Reverse Osmosis

Reverse osmosis is a type of membrane filtration that works by excluding particles from a concentrated solution. The core of the system is a semipermeable membrane, made of layers of material with incredibly tiny pores, measuring just 0.0001 microns in size. These pores are so small that they prevent unwanted minerals and impurities from passing through.

When pressure is applied to the water, it is forced directly against the membrane. This pressure causes the water to move in a "reverse" motion, pushing pure water molecules through the membrane while leaving the contaminants behind. The impurities are then flushed out through a separate, restricted outlet as wastewater. The water that comes out on the other side is 97-99% pure. For uses like pharmaceutical production or cleaning power lines, water is sometimes passed through more than one membrane to achieve 99.9-100% purity.

Because purified water lacks dissolved solids, it does not transfer heat as easily as tap water. This makes it a great choice for keeping car engines and manufacturing machinery from overheating. Conversely, it's not the most efficient for use in a geyser, as the appliance will use more electricity to heat the water.

The Role of Multi-Stage Filtration

Home water purifiers often have multiple stages of filters before the main RO membrane. This is crucial for protecting the membrane from clogging. Each filter stage removes a specific type or size of particle, thereby protecting the next filter and extending its lifespan.

It is essential to keep these pre-filters clean. If they become dirty and clogged, they hinder water circulation, which can cause bacteria to grow and worsen water quality. This forces the system to work harder, leading to more wastewater and potentially allowing contaminants to pass through the membrane, causing your RO system to perform below its capacity.