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Reverse Osmosis vs. Deionized Water Filtration: Which is the Winner?

In the battle of the best water filtration systems, which is better, a deionized water filter or a reverse osmosis filter? As a homeowner, you want to make sure your water is fresh, clean and safe for your family to consume and wash with. This is made easier with the help of a water filtration system.


There are numerous types of systems that are ideal for specific uses such as drinking, irrigation and washing.

Here are the biggest differences between two of the most popular systems: reverse osmosis (RO) and deionized water filtration (DI.)

How does Reverse Osmosis work?

reverse-osmosisWhile both systems work to remove impurities from the water, they both use very different methods to get there.

Here is how reverse osmosis works:

Natural osmosis is the process of moving a liquid from a high ion concentration to a low ion concentration. Reverse osmosis does the opposite.

RO filters use a specialized membrane to force the water into a low ion concentration, leaving behind impurities and minerals that may make the water taste bad.

How does a Deionized Water Filter work?

Many people assume that DI and RO filters are one and the same, however, they are very different.

Here is how DI filters purify the water:

This process has numerous uses in various industries such as pharmaceuticals, auto finishing, and textiles.

The process involves two steps. The first step passes water over positively charged ions. This removes metals and minerals from the water. The next step exposes the positively charged water to negative hydroxyl ions that cancel out the positive hydrogen ions. This leaves the water neutral, clean and pure.

Pros and Cons of These Filters

deionized-waterMuch like with any home appliance, there are negative and positive aspects of each system. Now that we know how the two work, let’s look at the advantages and disadvantages of each:


  • With a DI and RO filter, you will save money by not buying bottled water. This means that in a short period of time, the filter will pay for itself.
  • RO filters remove up to 99% of dissolved particles in the water.
  • With an RO and a DI filter, you will have peace of mind knowing that your water is pure and safe to use.


  • One of the biggest cons of an RO filter is the fact that the porous membrane is often big enough to let larger particles through, often requiring a second filter to ensure the purest water.
  • RO filters also tend to waste water, which could result in a higher water bill.
  • Some experts also say that DI and RO filters remove trace elements in the water that are actually healthy for humans and make the water taste better.

Whether you are interested in an RO filter or a DI filter, both have huge benefits and advantages. For more information on these systems, call 540-665-8196 and speak with experts at Powell’s Plumbing in Winchester, VA.

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