What is The Difference Between Reverse Osmosis and Deionized Water Purification

The Pure Truth About Water Purification

Are you looking for a home water purification system? It’s a good idea. Drinking and bathing in clean water free of impurities often found in city water systems, and even in private wells, is a healthy choice. It is also a wise choice for your budget. Household appliances work better and have a longer lifespan if the water they use is free of chemicals and minerals. An added benefit is that your overall plumbing system is less likely to get clogged and corroded.

While it is true that almost every municipal water authority must comply with the highest federal and state standards to ensure safety of the water supply, it is equally true that they routinely add chemicals such as chlorine to kill harmful bacteria and achieve that level of safety. Highly chlorinated water, however, is not the most pleasant water to drink.

As safe as public water is, it still often contains minerals as well as chemicals that run off into the water table. Most every water system contains a tiny percentage of potentially dangerous impurities. Adding a water purification system not only improves the taste of your water, it provides an extra level of protection. If you notice brown water coming from pipes, we have some tips for you. 

There are a variety of water filtration systems, including some very basic faucet and under sink filters, as well as home house systems. They all have their pros and cons. However, there are basically two kinds of systems that can get you the purest drinking, bathing and washing water possible:

    • Reverse Osmosis
    • Deionized Water Filters

The difference between reverse osmosis water and deionized water is the level of purity. Reverse osmosis removes solids to purify and improve the quality of drinking water, but the water is still saturated with salts and oxygen.

Deionized water removes these salts and oxygens, but the deionized process does not remove the dissolved solids found in the water. This is why it is common to combine reverse osmosis and deionized systems together to remove at least 95 percent of the impurities in your drinking water.

In this post we explain:

    • Reverse Osmosis and RO Water and how it works
    • Deionization and DI Water and how it works
    • Which might be the better option for your home

What is Reverse Osmosis and RO Water

Reverse Osmosis (RO) is one of the most efficient and modern water purification technologies. Originally designed to filter salt out of ocean water, RO can filter most known water impurities—up to 95 percent of all dissolved solids— found in municipal tap water.  The impurities RO removes include:

    • Organic Chemicals
    • Chlorine
    • Lead
    • Silicates
    • Pesticides
    • Herbicides
    • Arsenic
    • Asbestos
    • Radionuclides
    • Cysts

How Does an RO System Work?

The RO process  involves several stages of filtration. It usually starts with a pre-cleaning process. A pre-filter removes sediment, such as dirt and rust. Some systems may also use a carbon filter to reduce volatile organic compounds (VOCs) such as chlorine and other contaminants that give water a bad taste or odor. These filters are also placed at the end of the purification process, in which case they are called post-filters. However, they are the same kind of filters whether they are used in the pre- or post-treatment phases.

Water is placed under high pressure to force it through a reverse osmosis membrane. This membrane is a thick polyamide film with tiny pores large enough to allow water to pass through, but is small enough to prevent passing organic particles.  

The filtered water is held in a storage tank until needed. The system shuts off automatically whenever the storage tank is full and restarts whenever more water is needed for storage.

What is Deionization and DI Water?

Deionized water (DI) is exactly what the name implies, water that has had the ions removed from it. An ion is a particle that has a positive or negative charge. How does water get ionized?

Minerals from the surrounding soil, pipes and plumbing water passed through get dissolved on the way to your tap. When these minerals dissolve, they attach themselves to water particles; this attachment causes the ionization, meaning the particles have a negative or positive charge.

Normal unfiltered tap water is full of these ionized mineral particles (which is why DI is also sometimes called demineralized). These include:

    • Salt (sodium)
    • Magnesium
    • Calcium
    • Chlorider
    • Iron
    • Carbonates
    • Nitrates 

How Does a Deionization Water System Work

An ion exchange system consisting of small plastic resin beads attracts and retains the electrically charged mineral particles. Water  passes through the beads, the mineral particles bind to the resin beads, and the cleaned deionized water passes to a storage tank where it can be called upon as needed for drinking or bathing.

Deionized water is sometimes confused with distilled water, which is not the same. Distilled water is obtained through a process of boiling and steaming. Distilled water can still be ionized, and while it is a purer form of water, deionized water is more pure.

Which Water Purification System is Best for Your Family?

Historically, people have long consumed surface water found in streams, rivers, and lakes. Surface water is naturally low in minerals. Irrigation and wells, however, tap into groundwater that has a much higher mineral content. These minerals exist in a form and quantity that the body cannot easily absorb. Nor are they simply boiled away.

Water filtration is important, both for your family’s health and the environment. Some people with bad tasting water resort to bottled water for drinking, believing that even though the water contains contaminants it is good enough for showering and washing clothes. This is wrong on two counts:

    1. Bottled water isn’t always contaminant-free (indeed, there are varieties that are explicitly marketed as “mineral water”). Then there is the cost of buying a bottled product that you can readily obtain by turning on your taps. Equally, and perhaps more importantly, heavy use of bottled water contributes to the use of plastics that, even in areas that promote recycling, all too often end up in landfills and, worse, in our waterways and oceans. Plastics contain chemicals that are not healthy for the environment.
    2. Water full of contaminants isn’t good for washing, either for you or your clothes or dishware. Mineral particles and chemicals dull the skin, make your clothes and dishes dingy. And the shower and appliances themselves have shorter lifespans with deposits that build up over time.

Okay, so we’ve convinced you. But which water filtration system is best, reverse osmosis or deionized? 

The advantage of deionization is that it acts as a water softener as well as removing contaminants. The advantage of a reverse osmosis system is it also filters bacteria and viruses as well as pesticides and herbicides.

A combined deionized and reverse osmosis system offers the best advantages for your family’s well-being.

If you had to choose only one between reverse osmosis filters or deionized filters, then we think the better choice is reverse osmosis purification. It removes most of the contaminants in your drinking water, particularly the most dangerous ones. Also, the deionization filter by itself requires more maintenance as you have to change the filter more regularly.

The best way to make a decision, though, is to have your water tested. If you have well water, it is particularly important that you test your water at least once a year. Also, if you notice any change in the color, taste or odor of your water, test your water promptly.

A water test performed by an independent laboratory (you can see a map of certified California water testing labs here) can determine:

    • Basic water portability
    • The presence of potentially harmful organisms
    • Common contaminants found in groundwater (nitrate in particular can be particular dangerous for babies under the age of six)
    • Dissolved solids and minerals

Some county public health commissions provide water testing service free or at a nominal charge.

While it is an upfront expense, a water filtration system is a good investment. It eliminates the expense of bottled water, your clothes and dishware look cleaner (because they are), and appliances look longer. What it buys best of all, though, is peace of mind knowing the water you and your family drink not only tastes good, but is free of potentially harmful impurities.

Simply put, purer water equals better living

If you’re looking to dramatically improve your home filtration, talk first to a professional plumbing technician to determine the best water filtration system for your home. Since 2009, Benjamin Franklin Plumbing San Francisco has received Diamond Certification for our 92 percent customer loyalty rating and our exceptional customer satisfaction reviews. 

Benjamin Franklin Plumbing Bay Area offers a range of clean drinking water solutions with our home filtration systems and softeners. Having clean water is vital to your well being. We’re sure to find the water filtration system—reverse osmosis, deionization or both— that best fits your needs and budget.