UV Water Purifier VS Reverse Osmosis

UPDATED: September 5, 2022

The title of this article is a little misleading as a UV water purifier and a reverse osmosis system are completely different water systems. But many people have come to believe that they do very similar things and some people even think that they are interchangeable yet nothing could be farther from the truth.

A UV water system kills organic organisms but filters nothing from the water, and a reverse osmosis water system removes dissolved solids from the water but does not kill any organic organisms. Both are highly beneficial systems to improve the quality of your water, but hardly interchangeable.

Do I even need an ultraviolet or reverse osmosis system?

In fact, depending on your water quality characteristics, you may not need either of these systems or you may want to have both of them in your home.

Ok, let’s not jump too far ahead of ourselves here, let’s make sure we have a good understanding of what these systems do and don’t do and how they may benefit you, the homeowner.

First, let’s talk a little about what these systems do and how they are used in the home.

So what is an ultraviolet purifier system?

A UV or ultraviolet water purifier is usually installed very early on in the water system. This is because an ultraviolet purifier is used to kill organic organisms in the water entering the house making it usable for cooking and acceptable quality for drinking.

This does not mean that the water should be considered healthy by any means.

This simply means that consuming the water that has been processed through the ultraviolet purifier should not make you sick or cause any physical reactions that could be caused by harmful organisms like coliform or bacterias.

Proper installation of an ultraviolet water purifier is essential to ensure it is able to work correctly. It is recommended to install an ultraviolet purifier after a water pressure tank, and after any water softener, iron removal system or acid removal systems.

The reason for this is that the ultraviolet purifier needs to have the water be free of any substance that could cloud the water or impede the performance of the ultraviolet light. Hardness in water and iron in the water will collect inside the ultraviolet chamber and reduce the effectiveness of the system.

In most situations, a water softener will remove the hardness and iron from the water making it ok to then pass through the ultraviolet purifier.

An acid removal system that uses calcite to reduce the acid in the water will add hardness to the water and should be installed before the water softener so the softener can then remove the additional hardness added to the water.

Installing the ultraviolet system early on in your water system is to ensure that all of the water entering the home as well as going to outside outlets and sprinkler systems will be treated by the UV system making it safe to consume by humans and animals.

So what exactly does an ultraviolet purifier do?

Simply put, an ultraviolet purifier kills organic organisms that pass through it. Inside the UV purifiers chamber which is basically just a big pipe that is sanitized on the inside and has an ultraviolet light bulb inside it that goes the majority of the length of the system.

It is a long thin bulb, similar to a fluorescent bulb commonly used in ceiling fixtures where bright light is needed. But this bulb has a much higher intensity.

The ultraviolet light that is emitted from the ultraviolet bulb is invisible to the human eye but is very effective at using radiation to neutralize organisms like bacteria, viruses, pathogenic disease-causing microorganisms, and mold.

The ultraviolet bulb sits inside of an acrylic sleeve that looks a lot like a long test tube.

The light emitted by the bulb needs to be exposed to all the water passing through the system to be effective so if this test tube gets coated by hardness or iron in the water will go passed without being exposed to the radiation and therefore will still contain any live organisms that are in it.

Since this ultraviolet bulb needs to be at a certain amount of intensity to work, most manufacturers only guarantee the intensity of the bulb for one year. So be sure to have the bulb changed and the acrylic sleeve cleaned once per year to ensure the system is working properly.

So what is reverse osmosis?

Well RO or reverse osmosis is not as scientific and fancy as it sounds, let’s break it down. Osmosis is the adding of one thing into another thing, and that’s it.

If you go to see the ball drop in times square on new years eve and you walk into the crowd, you just experienced the process of osmosis. First, you were by yourself as an individual and then you became part of the crowd.

This may not be the best example of what osmosis is but it gives a simple understanding of it.

A better description of osmosis that is easy for most people to understand would be to add a spoonful of salt to a cup of water and stirring it in. You have now added the salt to the water, therefore you have performed the process of osmosis.

Now, what if we wanted to take that spoonful of salt back out of the water?

Well, then we would have to reverse the whole process, hence the term reverse-osmosis.

A little salt in my water doesn’t sound all that bad, why would I want a reverse osmosis system?

Well, a little salt in your water is not a big deal at all, a matter of fact, most people prefer having a certain amount of salt in their water because it adds flavor to otherwise empty tasting water that overly pure.

But some people’s water supplies have very high concentrates of salt in them, making the water taste unpleasant and even undrinkable.

Also, people that are on a low sodium diet for health reasons will benefit greatly from a reverse osmosis system as they will be able to greatly reduce the salt content of the water in their home and make it ok for drinking.

Most reverse osmosis systems are able to remove a very large percentage of the TDS that is found in water.

What the heck is TDS?

TDS is simply a measure of the number of dissolved solids found in a given sample of water.

TDS or (Total Dissolved Solids), is a count of dissolved solids in water and is often misunderstood as being Total Dissolved Salts. Although in most cases the amount of Total Dissolved Solids is primarily salt in the water, it is not actually a measurement of dissolved salts only.

To give an example of what amounts of TDS we consume on a regular basis.

Most of the popular bottled water that Americans consume, have a TDS of 10 or so and in some cases up to 60. The TDS level in your home can vary quite a bit, but a TDS of between 100 and 400 is very common.

Having a reverse osmosis system should be able to take about 90 percent or more of the TDS out of the water.

So if your household water at your kitchen faucet has a TDS count of 200 (not uncommonly high), an RO should be able to produce water with around 20 TDS, making it as free of total dissolved solids as many common bottled water brands.

So what exactly does a reverse osmosis system do?

You can think of a reverse osmosis system a bit like a coffee maker filter. The filter works as a membrane to allow only particles up to a certain size to get through while stopping particles larger than that certain size to get through.

You have coffee grounds in the filter that do not pass through it, then hot water is added which allows particles from the coffee to float in suspension within the hot water and they are small enough to now pass through the filter and into the coffee pot leaving the unwanted grounds behind in the filter.

Now we can enjoy the part that we wanted from the coffee and discard the unwanted part.

Well, that’s pretty much how reverse osmosis works, but reverse osmosis uses a much finer filtering membrane than a coffee filter.

A reverse osmosis system uses a semipermeable membrane which not only filters out very small particles but works as a one-way filter as well.

This simply means that when water with particles in it goes through the semipermeable membrane, the water can go back through the membrane in the opposite direction but still keep the undesired particles from getting through.

This allows the filtered water to be made and then stored under pressure so it can be dispensed without it flowing backward through the membrane.

During this process of reverse osmosis, the unwanted particles will get flushed away and the membrane will get rinsed off making it ready to filter out more particles again the next time it is needed.

Not sure about how often you should be changing your reverse osmosis filters? Check out my article on “How Often YOU Should Change YOUR Reverse Osmosis Filters“.

Reverse osmosis does not only remove salt from water.

Any particle that is in the water can be removed in part by reverse osmosis including pesticides, arsenic, bacteria, fluorides, and several others.

But it is important to understand that even the most expensive reverse osmosis systems will remove about the same amounts of total dissolved solids as the least expensive reverse osmosis systems.

Some may promise to provide more filtered water per day than others, but they all come with only about a 3 gallon storage tank anyway, and will likely provide more than enough drinking water for the average family as the storage tank starts to be refilled with new filtered water as soon as any water is taken from it.

If you find that you need more water than the system can provide with the storage tank that comes with it, you can easily add an additional storage tank for very little money. And none will remove all dissolved solids found in your water, and they shouldn’t.

But I want my water totally free of impurities?

It’s understandable that you would want your water as pure as you can make it, but think about why water has impurities in it in the first place. It is because water likes to have some impurities in it. Water naturally wants to hold some particles in suspension.

So if you were to remove all the impurities from your water and then consume it, what do you think it would do inside your body?

The water in your body would then take minerals from your body that may be good for you. Now you would have to drink an enormous amount of perfectly pure water to do any serious damage to your health, the point is that water does not have to be totally pure, just not overly full of unwanted contaminants.

Doesn’t reverse osmosis water have no taste to it?

Some people say that reverse osmosis water is too pure and has no taste to it. This can be true, and it will be a matter of personal preference for each individual.

If you are starting off with water that has a TDS count of only 100, you will likely have reverse osmosis water that has a TDS count of 10 or less which is very pure and has little taste.

Some people will add a mineral cartridge to their RO system to add a small number of good solids to the water and give it more flavor. It’s all up to personal preference.

Well I hope that you have a better understanding of how and why ultraviolet purifiers and reverse osmosis systems are not a one is better than the other choice, and many people have both. It all depends on what your individual water characteristics are and what you need to make your water better.

Related Questions:

Is high TDS in water harmful? Since TDS is a measure of Total Dissolved Solids and not anyone solid in the water, it will all depend on what those dissolved solids are and how much of them there are.

In most cases, the majority of the TDS in water is salt. We all know that excessive salt in your diet is not healthy, so of course, a high level of TDS in your water will not be beneficial to your health.

Generally, the amount of salt in drinking water is not excessive and not considered unhealthy. Most people will not even taste any salt in their drinking water. Check your drinking waters TDS with a TDS meter and discuss it with your doctor.

What is the TDS in bottled waters? I have tested several bottled water brands over the years and have found them to vary tremendously. I have found some with as little as 0 TDS and others with as much as 110.

You can test the TDS in the water yourself with a simple to use TDS Meter.

But that doesn’t mean that the ones with 110 TDS are poor quality water. Bottled water that says “Springwater” or “Stream water” are fine but may contain high levels of unknown TDS.

Some bottled waters use reverse osmosis to remove the bad dissolved solids from the water and then they add beneficial dissolved solids back into it. Minerals like calcium are good for you and add a pleasant taste to the water.

So don’t just go by the TDS level of the bottled water that you buy, high TDS in reverse osmosis water may be good for you.