Reverse Osmosis System Cost for Whole House or Under Sink

The reverse osmosis system is one of the most popular ways of purifying water at home. Many homeowners love its high effectiveness as it uses multiple semi-permeable membranes to deliver one of the purest waters you can get.

But as you are thinking of setting up this highly efficient water filtration system in your home, it will be vital to understand the costs that come with it.

You can expect to spend anything from $100 to over $1,000 on the initial buying cost alone for a simple reverse osmosis system. Here is a breakdown of the average cost of different RO system types.

Reverse Osmosis System


Whole House RO System

$1060 – $11200

Under Sink RO System

$360 – $1400

Counter top RO System

$150 – $1100

1. Whole House RO System

Whole House RO System


The whole house reverse osmosis systems are the largest of the three types and also have the highest filtration capacity. Hence, they will also be the priciest option.

Whole house RO systems are the types that connect to your main water line at the point of entry and filter water for the entire house. These machines will use more powerful and complex filtration technology to ensure you get filtered water from every tap in your home.

Initial Cost

For the small whole house reverse osmosis systems that can filter under 500 gallons per day, the prices will start at around $500 depending on the brand.

But for the medium size and larger ones that will filter thousands of gallons per day, the initial cost ranges from $1,500 to $10,000, but a few top-tier brands still sell their product for a little more than this.

Installation Cost

Those that allow for DIY installation and come with everything that you need will have zero installation cost. But, if you have to call in an expert for installation, you should be ready to part with $500 to $1,000 depending on the plumbing work needed and additional materials.

Maintenance Cost

Cost of maintaining and operating a whole house reverse osmosis system will depend on factors like the quality of the water and how heavily you use the system.

While regularly and heavily used systems will need more frequent filter changes, most systems will still need a filter change at least once per year. Depending on the cost of the specific filter type your RO system uses, you can expect to spend anything from $60 to $200 annually.

Note: For the commercial whole house RO systems, you can spend anything from $200 to thousands of dollars on maintenance every year. Besides the filters being more expensive, these commercial models will also often require occasional professional servicing.

2. Under-Sink RO System

Under-Sink RO System


Under-sink RO systems are the types that you will install in the cabinet below your sinks. They connect to the water line that takes water to your kitchen faucet, which means they will filter the water dispensed by your kitchen sink faucets only.

Initial Cost

Overall, these RO systems will be more affordable than whole-house models. The average cost of these systems will depend on the filtration process that it uses and other additional features like the addition of a booster pump.

That said, under sink RO systems will cost between $150 and $500. The advanced ones with a UV sterilization stage and permeate pump are more expensive.

For a commercial-grade, under-sink RO system, the average prices will start at around $500, and some high-capacity models will exceed $1,000.

Installation Cost

While some under sink RO systems can be quite tricky to install, most will be designed for DIY installation, which means you will hardly very need to incur any installation cost.

If you do not have any DIY skills and have to pay a plumber for the installation, the average installation costs range between $150 and $300. What’s more, if there are significant modifications needed during installation, the additional charges can push the expense to $500 or more.

Maintenance Cost

Like any other RO filtration system, the under sink types will also come with filters that will need changing every 6 to 12 months. Hence, the maintenance cost also mostly stems from having to buy replacement filters.

Annual filter costs for these systems are between $60 and $100, and because the filter change process is often straightforward, that is all you need to spend on the maintenance.

Note: While the more the filtration stages an under sink RO system has, the more efficient it is; this also makes the system more expensive to maintain as there will be more filters to replace.

3. Countertop RO System

Countertop RO System

Photo: NU Aqua

Countertop RO systems are the simplest of the three types, and they are designed to be more portable and affordable.

These RO systems are designed to sit on the counter and are super easy to set up as they will not have many hardware.

Initial Cost

Depending on the capacity of the countertop RO system, the brand, and also the additional features that it has, you can expect to pay between $100 and $1,000 to get one.

You can also find a few basic models in the market that will retail for under $100, while some more advanced ones from top brands can still cost way much more.

Installation Cost

The setup process for countertop RO systems entails attaching the unit to your kitchen faucet, which takes just a few minutes and hardly requires any significant plumbing skills. The simplicity of this process means anyone can do it. Hence, in most cases, the installation cost is zero.

Maintenance Cost

Besides being more affordable, the countertop RO systems will also be cheaper to maintain. And this is mostly because the filters do not have a lot of hardware and only have 3 to 5 stages, which means there are fewer filters to replace.

For a simple 4-stage countertop system, you can expect to spend between $50 and $80 on maintenance every year, but for a 5-stage model, the cost can go as high as $100 or even more.


A reverse osmosis system provides a highly reliable method of cleaning water at home. Whether you want to remove harmful contaminants from your water or even improve its taste and smell, one of these systems will be very useful for you.

But as you are choosing one, whether it is a whole-house unit or the smaller countertop models, you need to make sure that besides the initial cost, you also consider the installation and maintenance costs.

With that in mind, it is always a great idea to pay more for a high-quality reverse osmosis system because, besides giving you better water quality, these systems are also cheaper to maintain.