How Much Does a Reverse Osmosis Filter System Cost with Installation

By Rehan Iqbal

Is a reverse osmosis filter right for your water treatment needs? How much does it cost to buy and install one of these filters? What alternatives should you consider? We're here to answer your questions, so you can make the right choice when you upgrade your water treatment equipment.

How Much Does a Under Sink Reverse Osmosis System Cost?
Can I Install an Under Sink Reverse Osmosis System?
How Much Does it Cost to Install an Under Sink Reverse Osmosis System?
How Much Does a Whole House Reverse Osmosis System Cost and to Install?

Plumber Installing a Reverse Osmosis System

How Much Do Under Sink Reverse Osmosis Systems Cost?

Prices vary widely depending on features, with under sink reverse osmosis systems typically ranging from $200 to $600. Tankless systems are the most expensive, because they need large RO filters to maximize water flow rate. Adding a larger storage tank or choosing a system with more filters also increases cost.

Be sure to budget a little extra if you want to hook up your under sink RO system to your fridge. If you already have a water line running to your refrigerator, you just need to add a T connector. This lets you send treated water to the faucet and the refrigerator. If this is a new installation, you’ll also need to add hose and clamps to run between the RO outlet and your fridge. Most manufacturers offer the hardware you’ll need as an add-on.

When you buy a system, it’s important to factor in the cost of replacement filters and their size. On average, an RO filter lasts two to three times longer than carbon and sediment filters. Larger filters last longer, but they may not fit in the space under your kitchen sink. Filters cost anywhere from $60 to $150 per year, depending on the number of steps in your RO system.

Can I Install an Under Sink RO System Myself?

If you can replace a faucet and drill holes, you can probably install an under sink RO system. You’ll need to drill a hole in your sink to mount the faucet, and another hole to connect the system’s waste water line to your sink’s drain line. From there, you just need to place the filters and run lines between everything.

How Much Does it Cost to Have a Plumber Install My Under Sink System?

Expect to spend between $100 and $200, depending on the complexity of your RO system.

How Much Does it Cost to Buy, Install and Use a Whole House Reverse Osmosis System?

Why are most RO systems only used for drinking water? Because whole house reverse osmosis systems are expensive, and come with their own problems. Here’s what you can expect if you choose this water treatment option.

The cheapest whole house RO systems sell for as little as $1,500, but units with enough capacity for a an average home cost between $6,000 and $20,000. Installation costs vary widely, depending on how close you can get the filter to your water main. If you can fit the system next to the water main, expect to pay a plumber between $200 and $500 for their part of the installation. If you can’t get the filter next to the water main, expect to spend at least an additional $5 per foot of pipe. If the plumber needs to dig or or cut holes in walls to run the lines, installation prices can easily exceed $1,000.

You may need to have an electrician wire up the pump. Like plumbing, prices vary depending on distance. If you don’t have ready access to a socket, expect to spend at least $200 for a new circuit and wiring.

Reverse osmosis removes all dissolved solids from water. Without these solids, water readily absorbs anything it comes across, including copper from pipes and lead from pipe solder. This can make your water toxic, and the water will eat away at your plumbing, leading to leaks. All metal pipes must be replaced by polyethylene (PEX) pipes before you can use a whole house RO system.

By using a whole house system, your water usage will be 2-5 times higher, as most of the water entering your home is turned into waste water. This might be too much water if you use a well. If you get water from a utility, this will have a big impact on your water bill.

Expect to spend between $200-$300 in electricity per year to drive the pump. Whole house systems typically come with just a carbon filter and a sediment filter. Be sure to factor in their replacement costs when you’re looking at RO systems.

What is a Reverse Osmosis Filter System, and Why is it More than Just an RO Filter?

There are four reasons why filter systems include more than just a reverse osmosis filter:

Chlorine damages RO membranes, so it must be removed before the water reaches the filter.
RO filters have pores that filter down to a fraction of a micron. To keep the membrane from clogging constantly, the water needs to be pre-filtered.
RO filters are expensive. By doing as much of the filtering beforehand with cheaper filters, the system can use a smaller RO filter.
Since it depends on water pressure to work, adding an RO filter slows down water flow. To compensate, whole house systems add a pump to push water through the membrane, while most under-sink systems have a storage tank to give the system time to filter water before use.

All RO systems include an activated carbon filter to remove chlorine. Most systems also include a catalytic carbon filter, a KDF filter, or both to remove even more chlorine. These filters also remove other contaminants, improving the flavor of water. Most systems also have a sediment filter, which prevents large particles from clogging other filters in the system.

Reverse osmosis removes so much that it leaves water tasting flat. Some systems compensate by adding a remineralization filter. This filter contains magnesium and calcium that dissolve into the water. This slightly increases water hardness, but not to a degree that it will cause staining around the faucet.

What Does a Reverse Osmosis System Treat, and What Alternative Treatment Methods are Available?

Since an RO system contains several filters, it removes more than an RO filter alone. However, these systems aren’t always the best option for treating your water.

Reverse osmosis is the best solution for removing these contaminates:

Sodium chloride - This is the same salt used for cooking, and the salt found in sea water. It’s also commonly used in ion exchange water softeners. Reverse osmosis removes 99% of this salt from water. It’s the only practical way to desalinate water at home.
Chromium – Some forms of chromium can cause nerve damage. Like sodium chloride, chromium can only be effectively removed from your home’s water using a reverse osmosis system.
Nitrates - RO filters are the most effective method of removing nitrates and nitrides. These chemicals are common in wells near farmland, due to agricultural runoff.
Fluoride - RO filtration is the most effective way to remove fluoride, stripping out 99% of this chemical. The only alternative treatment for most home water systems is bone charcoal. Activated alumina also works, but only with acidic water.
Potassium - RO filters are highly effective at removing potassium permanganate, a chemical used in oxidation systems, and potassium hydroxide, a mineral naturally found in water.

Reverse osmosis systems are an option for treating these contaminates:

Lead - An activated carbon filter removes up to 95% of lead in water by itself. The reverse osmosis filter removes up to 99%.
Copper - RO filters are effective at removing this metal, as are ion exchange water softeners.
Arsenic - Arsenic comes in two forms: arsenic 3 and arsenic 5. A reverse osmosis filter can only remove arsenic 5. To treat arsenic 3, it must first be oxidized, which converts it into arsenic 5.
Agricultural chemicals - An RO membrane can’t filter out herbicides or pesticides. However, activated carbon has no problem trapping these chemicals.
Chlorine - This chemical destroys RO membranes. Activated and catalytic carbon remove this chemical, protecting the RO filter while improving the taste of your water.
Radium - RO filtration removes almost all radium. Activated carbon removes up to 70% of radium in water by itself. Ion exchange water softeners are also effective, especially if they use calcium hydroxide (lime.)
Sulfates - Activated carbon filters remove up to 1 mg/l of sulfur. For higher amounts, you need to use an oxidation system.
Phosphorous - Phosphorous is another contaminate that comes from agricultural run off. Although it isn’t dangerous, phosphorous gives water a bad taste. Both RO and activated carbon filters are effective at removing this chemical.

RO filters don’t work well on these contaminates:

Bacteria – These pathogens can’t pass through an RO membrane. However, the membrane will develop holes and tears over its service life that let bacteria through. For this reason, manufacturers do not recommend using an RO system to remove pathogens.
Hydrogen sulfide - KDF and catalytic carbon filters can remove small amounts of this gas. However, you’ll need to turn to oxidation systems to remove heavy contamination.
Calcium and Magnesium - RO filters remove small amounts of calcium. However, ion exchange water softeners and nucleation water conditioners are better treatment options for hard water.