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Home » Reverse Osmosis Systems » How to Choose a Reverse Osmosis System

How to Choose a Reverse Osmosis System

By: Craig Smith
Last Updated:
How to Choose a Reverse Osmosis System

So, you have decided that the time is right for you to purchase a reverse osmosis (RO) filtration system.

That’s great but now you have the task of sorting through the numerous reverse osmosis system options that are available in the marketplace.

Believe me when I say there are many of them. You can easily spend a day or more trying to find the right RO system for you.

I am here to help make this task easier. This begins with me discussing what you need to know before starting to shop for a reverse osmosis system.

I will also go over the different types of RO systems that are available and what they work best for.

By the time that you get done reading this information on how to choose a reverse osmosis system, you will have significantly narrowed down your search parameters.

This will cut down on the time you spend looking for an RO system and help find one that best meets your family’s water purification needs.

What to Know Before Reviewing & Purchasing an RO System?

Here is some reverse osmosis filtration system information that you should be well aware of before starting to shop for one:

1. Do I Need To Buy A Faucet?

Many point-of-use RO systems will only work with a special faucet. If that’s the case, you will probably not have to worry about shopping for a separate faucet. Most likely the manufacturer will include it in the package if it’s required.

2. How Many Stages Of Filtration Should It Have?

Most RO systems will come with at least three stages of filtration. This includes a sediment filter, a secondary pre-filter (most likely activated carbon-based), and the stage that contains the reverse osmosis membrane.

It’s also what I would call the minimal number of acceptable stages.

A good rule of thumb here is to test your home’s tap water. The worse the quality of water that you have is, the more stages that you want on your system.

Additional system stages may include alkalizers (adjust pH), UV light purifiers, mineralizers, water conditioners (salt-free water softeners), and possibly even some other filter types.

Express Water Reverse Osmosis System

Pictured above is the Express Water Reverse Osmosis System that features 11-stages in total. That is about the max number of stages that you will find on a RO system.

3. Do You Also Need A Softener For Water Hardness?

Although your reverse osmosis filtration system will eliminate some hard water-causing minerals, it is not designed to be a water softener.

So, if your incoming tap water has a hardness level of 60 ppm or mg/L or more, you should strongly consider adding a water softening stage to your system.

That being said, RO does remove a good amount of hardness causing minerals, so if your water hardness is low then it should be fine.

4. Does An Ro System Waste Water?

Yes, Reverse Osmosis systems waste water. It’s just a natural byproduct of the type of filtration process that they use. It used to be that if you had a reverse osmosis system, you could expect 60% or more of the water that enters into them to end up as wastewater.

Fortunately, this is a characteristic of RO systems that has started to change. More efficient ones are now becoming available.

5. What GPD Or Production Should I Make Sure Of?

When shopping for an RO system, you will notice that they have a gallons-per-day (GPD) rating on them. This is the max amount of purified water that a reverse osmosis system will produce in 24-hours.

For point-of-use RO systems, a rate of 50 GPD or higher is recommended. The recommended GPD factor for point-of-entry systems should be calculated by factoring in 100 GPD of water use for each member of your family.

This will be explained in more detail later on in the article.

Should I Get A Point-of-Use or Whole-House RO System?

To help answer this question I will start by going over the 3 main types of RO systems. 

1. Countertop RO

waterdrop ro

As you can imagine, these are the smallest size reverse osmosis systems. That only makes sense since they are RO systems that you don’t want to overcrowd your entire countertop.

But don’t be fooled by their size. Some countertop reverse osmosis systems can be quite sophisticated for their size.

A good example is the ‎Waterdrop ‎WD-G3-W pictured above. Despite its 18” x 5 ½” x 18” size, it still features a tankless design, 3 filtering stages, and an internal booster pump to increase GPD production.

2. Undercounter RO (Under Sink)

These are the most commonly found reverse osmosis systems. That has a lot to do with the fact that they are point-of-use systems that produce high-quality drinking water and yet stay out of sight. Many will even come with a faucet or smart faucet.

An example of a well-reviewed model is the APEC Top Tier Supreme Certified Reverse Osmosis Water System in the photo above. It comes with a storage tank, 6-filtering stages, and an included luxury faucet.

3. Whole-House RO

Whole-House RO

While the first two reverse osmosis system types on this list are point-of-use options, these are point-of-entry systems that are designed to supply your whole house with high-quality tap water.

They take up much more room than point-of-use RO systems and they will lighten your wallet too. Most also have options where UV light purifiers and water conditioners (salt-free water softeners) can be added to them.

Pictured above is the Crystal Quest 7000 GPD Whole House Reverse Osmosis System. With a 550-gallon storage tank and booster pump-assisted reverse osmosis filtration, it can supply even the largest size families with enough pure water to meet their daily needs.

So, Which Type Is Right For You?

A couple of main factors determine which model type is best.

1. What Will Your RO System Be Used For?

Are you only concerned with the quality of the water that you drink and use for cooking? If that’s the case, then you only need a countertop or under the sink reverse osmosis system (point of use systems).

For anything more than that you will need a whole-house reverse osmosis filtration system (point-of-entry systems).

2. What is Your RO System Budget Range?

Another question is how much you are willing to spend on a reverse osmosis water purifier. Point-of-entry systems are expensive and typically run in the 1,000’s up to $10,000 when storage tanks are added.

Quality point of use reverse osmosis systems are commonly found for around $300-$800.

What Size RO System is Best?

Here I will try to explain one of the most misunderstood aspects of reverse osmosis systems which is the number of gallons per day (GPD) an individual RO system can produce.

Understanding RO GPD Ratings

I will start by saying that this is a characteristic of RO systems that you have to be careful not to get too caught up in.

This is especially true when you are only looking to buy a point-of-use reverse osmosis system to purify water for drinking and cooking purposes.

Most families will not use more than 10 to 15 gallons of water a day for these purposes. So, it will not matter too much if you have a point-of-use RO unit that is rated at 20 GPD or 700 GPD.

The only consideration here is if you want your RO system to produce purified water more quickly. Then you would want to have a system with a higher GPD rating.

The higher the GPD rating an RO system has, the faster it will produce filtered water.

Keep in mind that you can eliminate some point-of-use RO system GPD concerns by simply adding a 3 to 5-gallon storage tank to your system. Higher GPD rates are a necessity for tankless RO systems.

A GPD rating takes on a much more significant role when it comes to whole-house RO systems. This is because your system will have to produce enough purified water to meet your family’s entire daily use needs.

Point-of-entry RO systems come in two forms. The first is a high GPD tankless RO system (manufacturers still recommend the use of 10 to 30-gallon storage tanks with these) that has pressure-enhancing booster pumps and multiple membranes.

The other way that whole house reverse osmosis filtration can be accomplished is by having a high GPD traditional reverse osmosis system with a significant size storage tank (300-gallons or more). 

What GPD rating should you get?

As was mentioned before, if you are buying a point-of-use RO system, try to get one that is rated at least 50 GPD.

For whole-house systems, you have to figure 100 GPD for each member of your family. As an example: if you have a family of 5, then a system rating of 500 GPD should work for you.

Other RO System Purchasing Factors to Consider

Some other reverse osmosis system traits to consider when shopping for one:


You have to have enough space to install the type of RO system that you are looking to buy. This is especially true with larger whole-house reverse osmosis systems.

They can take up a significant amount of floor or wall space in a basement or garage, especially if they have a water softener component and other add-ons.


I will start by saying that most reverse osmosis membranes will eliminate or significantly reduce 99% or more of the contaminants in water that are not soluble. So, where the difference in a system’s effectiveness comes in is usually in the other stages in the system.

These are such additional treatment stages as water conditioners (salt-free water softeners), carbon block & sediment filters, UV light purifiers, and alkalizers.

Ease of Installation

If you have a little mechanical knowledge, then you can probably figure out how to install most point-of-entry RO systems yourself. Under-the-sink models are a little bit more difficult to install than countertop models.

Whole-house point-of-entry RO systems are a completely different animal. In most cases, you would be wise to have a professional install these.

Ease of Maintenance

Most RO systems do not require much maintenance. That’s one of their selling points. But they are not maintenance-free.

Check out our article on reverse osmosis maintenance for a deeper look.

They have filters that need to be changed periodically. Usually, the more stages that an RO unit has, the more filter replacements there are involved in maintaining them.

Wastewater Created

If you are into living a greener lifestyle, you have options now when it comes to more efficient reverse osmosis systems in terms of the amount of water that they waste.

This is because booster pumps and additional membranes are being added to them to increase pressure in the system to speed up the filtration process. This also cuts down on the amount of wastewater that they generate.

So, be aware of this when shopping for an RO system if you prefer to have an environmentally friendly model.


If you are like most people, obtaining a reverse osmosis system is a big expenditure for you. That means it’s something that you want to last you for a while. Paying close attention to how your RO system is constructed is the key here.

The more plastic polymers, stainless steel, and other metals it’s constructed with usually lead to a longer lifespan. Make sure you also know what type of warranty that any RO system you are thinking about purchasing comes with.

It also stands to reason that the longer and more comprehensive a warranty is, the more confidence a manufacturer has in their RO system’s construction and quality.

Conclusion & Where to Buy

As you can imagine, in my 26-years in the swimming pool and hot tub industry, I spent many hours working around water filters and other water purification devices. Because of this, I have learned to place a high value on having access to the purest water possible.

That’s why I am a big fan of reverse osmosis water filtration systems. They tend to eliminate or significantly reduce many of the most worrisome impurities that are commonly found in tap water.

I always recommend them to my family and friends that are shopping for water filtration devices.

They are also very easy to find because of how popular RO systems have become. There most likely will be a store or home improvement center in your area that will carry them.

I found my under-the-sink reverse osmosis system by shopping online. This is the option that I feel gives you the most choices when shopping for one and eliminates the hassle of driving around and dealing with traffic and finding parking spaces.

No matter how you go about obtaining a reverse osmosis water purification system, it’s a choice that you really can’t go wrong with.

Photo of author
Craig Smith
Craig got his start in water working in the swimming pool and spa industry. Water treatment would grow into his main career but he ended up working in the pool industry for over 26 years where much of his time was spent balancing the water in customer's swimming pools and installing water filtration equipment. Craig offers an abundance of water treatment knowledge after helping homeowners get pure water for 26 years.

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