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How Does a Reverse Osmosis Water Filtration System Work?

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Are you considering buying a reverse osmosis water filtration system, but you’re unsure how they work? Do you wonder what reverse osmosis is, or if it is healthy to drink reverse osmosis water? Has it been a long time since ninth-grade biology when you last heard the word ‘’osmosis’’ and don’t remember what that means, much less what the reverse might entail?

We’ll break down exactly what reverse osmosis filtration is, what a reverse osmosis system removes from water, and answer commonly asked questions about how reverse osmosis systems work so you can decide if it is right for your Granbury, TX home without going back to high school science class. (You’re welcome).

What Is Reverse Osmosis Water Filtration?

Reverse osmosis (RO) is a water purification technology that uses a semipermeable membrane to remove unwanted molecules and larger particles from drinking water. Reverse Osmosis (RO) water filtration is highly regarded as the most convenient and effective method for purifying drinking water. Because unlike chemical or carbon filtration systems, which use certain materials to attract or directly target the contaminants in the water, reverse osmosis works by pushing water through a microscopically small filter material. It works at the molecular level to eliminate up to 99% of common impurities and dangerous contaminants from water, such as chemicals, bacteria, metal, dirt, and other organic compounds.

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How Does Reverse Osmosis Work?

Normally, osmosis is the process by which molecules pass through a membrane from a weaker-concentrated solution into a stronger-concentrated solution until both solutions are of the same concentration. Reverse osmosis is still the same fundamental osmosis process; it simply involves adding higher pressure to move the water molecules out of the stronger solution (the contaminated water) and into the weaker solution (the pure water). Because of the microscopic pores on the semi-permeable membrane filter, reverse osmosis can not only remove the obvious visual contaminants such as sediment and larger organic material, but it can also remove dissolved substances from within the water.

What Does a Reverse Osmosis System Remove?

A reverse osmosis water filtration system effectively removes a wide variety of contaminants from water. Here are some of the things it can remove:

  1. Dissolved salts: Reverse osmosis is very effective at removing salt from seawater, which is why it is often used in desalination plants.
  2. Heavy metals: RO can remove heavy metals like lead, mercury, and arsenic, which are harmful if ingested.
  3. Microorganisms: RO membranes can filter out bacteria, viruses, and other microorganisms, making them an effective tool for ensuring biological safety in drinking water.
  4. Chemical contaminants: Certain chemicals, such as some pesticides and pharmaceuticals, can also be reduced or eliminated by reverse osmosis.
  5. Sediments and larger particles: While these are typically removed in pre-filters before the water reaches the RO membrane, if present, the RO process would remove these as well.
  6. Dissolved solids: Total Dissolved Solids (TDS) are any minerals, salts, metals, cations, or anions dissolved in water. RO is effective at removing a high percentage of these.

It’s important to note, however, that while reverse osmosis is very effective, it’s not perfect. Because of how effective this water filtration treatment is, a reverse osmosis system will even remove beneficial minerals present in water, meaning many reverse osmosis systems will run the water back across mineral beds to add those positive minerals back into the water. Some contaminants, like certain volatile organic compounds, pesticides, and solvents, can slip through the membrane. That’s why many systems include activated carbon filters, either before or after the RO process, to catch these other potential contaminants.

Does a Reverse Osmosis Water Filter Remove Healthy Minerals?

Yes, a reverse osmosis system does remove some healthy minerals from water. The effectiveness with which these systems filter water does not stop at only the bad contaminants. This is because the RO membrane doesn’t distinguish between “good” and “bad” dissolved substances — it simply removes anything larger than a water molecule.

The minerals that may be found in water and are often cited as beneficial to human health include calcium, magnesium, and potassium, and other bicarbonates, as well as municipally-added fluoride. (Which is good for teeth.) For those concerned about mineral loss, RO systems come with a remineralization stage. During this stage, beneficial minerals are added back into the purified water after it has passed through the RO membrane. These systems can help strike a balance between purification and mineral retention in your drinking water.

How to Determine Which RO System Is Best for You

  • Price: RO water filters can be pricey. The amount of water you need to filter per day will affect the price of the filter you buy. (A larger household and/ or lots of water usage = a larger filtration system.)
  • Water Pressure Conditions Before Installation: RO filtration systems rely on water pressure to function, so make sure your home can handle it before purchasing your filter. Low water pressure will reduce the flow of water coming from your faucet, resulting in more waste and decreasing the efficacy of filtration.
  • Capacity and Speed of Water Production: How much water you use will determine the capacity of the semipermeable membrane or gallons per day (GPD) of the unit you need. The higher the GPD number, the higher the production membrane

What to Look for in a RO Water Filtration System

  • Efficiency: The reverse osmosis system should tell you what types of contaminants they can filter & how successful they are at doing so to produce clean, great-tasting water. You’ll also want to find how much wastewater they produce.
  • Replacement Filters – Ease of Installation and Affordability: Keeping your RO filter effective means replacing the filters as needed, and the price of filter replacements can vary significantly. Before you buy, look at how easy or difficult it is to get these filters replaced (and whether that will require hiring a professional such as Justice Plumbing), as well as how much the individual filters will cost, to make sure you can keep up with your RO filtration system maintenance.
  • Quiet and Fast Water Flow: Reverse osmosis systems make water slowly, and the speed of water flow varies greatly between systems. Highly filtered water with low contaminants takes time to produce. You’ll want to shop for a system with a storage tank that can hold the water you’ll need to get through your routine so you never have to wait for it to purify. IIt’salso worth researching how quiet your RO system will be to avoid loud gurgling noises as it filters water, even when you aren’t using it.