Reverse Osmosis System Installation How-To – RO Install Is Not as Hard as You Might Think

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Adding a reverse osmosis filtration system in your home is a wonderful choice for so many reasons. It’s one of the best ways to get ultra-pure, contaminant-free water – ro water is about as pure as it gets! When you first purchase your new filtration system, however, the setup will be a little more complicated than hooking up a typical under sink water filter.

Fortunately, you don’t need to be a plumber or a professional handyman to successfully install a reverse osmosis system.

Step by Step Instructions to Hooking Up Your New Under Sink RO Water Filter System

How to install a reverse osmosis system? Well, the first step to any DIY assembly project is to make sure you have a clear idea of what the entire process entails from beginning to end. Before you start working, read this entire guide making sure you have all necessary equipment and know-how to avoid time-wasting mistakes. Let’s get started!

Before You Buy…

Don’t forget to look at the dimensions of the ro unit you’re considering, and measure the space you intend to install it in. The cabinet will need to be large enough to store both the filter module and tank, so double check before clicking the order button. While you’re at it, check to be sure there’s a cold water line available to feed the system. This is rarely an issue, but it’s better safe than sorry! After you’ve established the system is a good fit, gather all your tools and materials.

If you haven’t decided for a certain model yet, consult our reverse osmosis system reviews.

Here’s What You’ll Need:

  • A new reverse osmosis module and owner’s manual
  • An ro water storage tank
  • A permeate faucet
  • A reverse osmosis membrane
  • Pre- and post-filter cartridges
  • An installation kit – components may vary, but most kits will include a T-valve, tank valve, drain saddle, faucet connecter, a wrench for the filter and membrane housings, and tubing.
  • A power drill and drill bits to match the type of faucet being used
  • A regular old screwdriver
  • An adjustable wrench
  • A utility knife
  • A towel or two to keep your workstation clean and dry

Naturally, the exact tools required will vary slightly depending on which model you purchase. Most ro systems already come with a storage tank, filter cartridges, and an ro membrane, so check what’s included with your model of choice before you make any additional purchases. To be sure you have the right tools, consult the owner’s manual.

reverse osmosis water filter system

Choosing the Perfect Installation Location

Generally speaking, the kitchen is the preferred location for most reverse osmosis systems. It’s the most frequently used faucet, providing easy access to purified drinking and cooking water. The problem that can arise with kitchen sinks is a lack of space. If you don’t have spacious cabinets, it may be impossible to fit an ro system under the kitchen sink.

If that’s the case, you’re not out of options. The filter can easily be installed in a basement or garage with a water line running up to the kitchen. The only challenge of garage installation is temperature. Don’t install a reverse osmosis unit in a location that gets cold enough to freeze. Also, make sure you install the unit on a cold, not hot, water line, following any other water treatment devices.

Reverse Osmosis Installation – Time to Get Started

Ready? You’ve got this. As long as you’ve checked off all the required tools on your checklist, the installation process should go smoothly. As with most DIY projects, there are plenty of online video tutorials to walk you through it if you run into any trouble.

Disclaimer: Always consult the owner’s manual for exact instructions and check your local and state codes before making any changes to your home plumbing system.

1. Set up that shiny, new faucet.

Reverse osmosis systems usually don’t feed to your existing faucet. Instead, they rely on a second faucet to deliver purified water straight to your sink. Unless you had a previous system set up, your sink most likely will need a new hole to be drilled for the new faucet.

reverse osmosis faucet installation

Choose a convenient location that doesn’t get in the way of your usual cooking activities. Depending on the material your sink is made of, you may need to purchase a specific kind of drill bit to avoid damaging it. If you’re drilling a ¼ inch hole, you don’t need a pilot hole. For ⅜ or ½ inch holes, drill a ¼ inch pilot hole beforehand. After marking the spot using a center punch, grind away a small amount of the surface to anchor your drill bit before beginning to drill into the sink. If you’re dealing with metal, take it slow and try adding a tiny bit of oil.

After the hole is drilled through, carefully clear away any debris left behind. If there are any sharp edges, sand them gently. Then, slide the new faucet stem into the hole and secure it from below the counter. Finally, screw on the quick connect fitting with your fingers, using a wrench to finish the job.

2. Yeehaw! Time to add the drain saddle.

Guess what? You’ve already finished the hardest part. From here, it just gets easier. The drain saddle is a funny name for a simple adapter that connects your reverse osmosis system with the sink drain line. It should be positioned as far from the dishwasher discharge and garbage disposal as possible, and a minimum of 5 inches above the p-trap to keep your ro system from getting contaminated or blocked. If that sounds like complete gibberish, a YouTube tutorial can give you a visual of where the saddle should go.

Once you’ve established the correct location, drill a 1/4” hole in the top or side of the drain line. Now, attach the saddle using the clamps and bolts.

3. Install the feed valve.

The feed valve is exactly what it sounds like. It’s a valve that connects your new reverse osmosis system to the cold water line. Before you start, shut off the cold water valve. To release built-up pressure in the plumbing system, open the kitchen faucet. Wait until water stops flowing. Now, just remove the tubing from the cold water valve and install the feed valve, connecting the cold water tubing. If it doesn’t fit correctly, you may need an adaptor.

4. Next, you’re ready to install the permeate storage tank.

If you’ve ever purchased a gallon of distilled water, you know how heavy it is. A water storage tank can hold several gallons of water, so it’s going to be too heavy to move frequently. Even if you’re short on cabinet space, keep the tank less than 10 feet from the faucet, or the water pressure might drop and slow the flow rate. If you’re struggling to find a good spot, keep in mind that it’s fine to place storage tanks on their sides if it fits better that way.

Once the location is finalized, wrap several layers of Teflon tape around the port on the top of the tank. Then, just screw on the tank valve by hand and your storage tank is ready to go!

5. Now we’re getting to the good stuff: mounting the ro module and connecting the tubing.

It’s not strictly necessary to mount the module. But if you do, make sure there’s enough space under it to replace filters and clean the reverse osmosis system.

Feed the tubes into the correct fittings and push them in until they won’t go any further.

  • Feed water line – The feed water line connects the feed valve to the reverse osmosis module feed port.
  • Drain line – The line should branch from the flow restrictor of the ro module to the drain saddle. Make sure the water flows downwards and avoid tubing kinks or loops.
  • System-tank line – Attach the line to the filtration system outlet port and the other end to the tank valve.
  • Post-filter-to-faucet line – The tubing should match up with the post-filter outlet and the fitting of the ro water faucet.

How long should the tubing be?

Trim the tubing so there’s enough slack to move the module and tank around slightly, but not so much that there are loops of leftover tubing.

6. You’re almost done!

The setup is pretty much complete, but you haven’t installed a few crucial filter components yet! The exact components vary from system to system, but usually there’s a sediment pre-filter, a carbon filter, and finally the reverse osmosis membrane. Some units also come with post-filters.

Place the pre-filters and the ro membrane into their housings.

  1. Detach the filter housings.
  2.  Put in the cartridges.
  3. Reattach the housings where they belong checking the O-rings are seated properly.
  4. Tighten gently with the included filter wrench.
  5. Adding the ro membrane is even easier. Take off the housing cap, slide the membrane cylinder into the socket, and replace the cap.

7. All systems are go!

At last, you’re ready to rev up your new reverse osmosis water filter system and take it for a spin.

Just turn the water supply on once more, and open the feed valve and the ro faucet, without opening the storage tank valve. If you hear odd bubbling sounds, it’s nothing to worry about. This will stop once air pockets have escaped the system. Check for any leaks, tightening connections as needed. Within 15 minutes, water should begin spilling out of the faucet. At first, it will be a bit stained from the carbon filter, but the residue will wash away quickly. Now, turn off the faucet and open the storage tank valve. At this point, the tank will begin to fill.

While you’re waiting, clean up your workstation and review the owner’s manual to make sure you didn’t miss any important details. It can take up to several hours for the tank to fill completely, so you’ve got time. When it’s full, turn on the ro faucet and allow all of the newly purified water to flush out. Repeat the process one or two more times, and then your reverse osmosis system is ready to use!

Pouring water into glass

Not a DIY Master? Don’t sweat it!

Installing a somewhat complicated water filtration system isn’t everyone’s cup of tea. If you’d rather sit back and relax while someone else handles the assembly, just contact your trusted local plumber. Under sink ro systems will cost around $200-300 to install, on average. Whole house reverse osmosis systems are a lot more labor intensive, so installing those usually costs $500 and up.

If you don’t have a plumber you already love, online review sites can help you to find someone reliable and fair. Yelp, HomeAdvisor, and Google Reviews are all reputable. You can also reach out on Nextdoor and local Facebook groups to ask for recommendations.

Whichever route you choose, best of luck! If you have any questions, just send us a message or post in the comments.

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