Looking for the best accessories to upgrade or modify your reverse osmosis system?
You’ve come to the right place.
Reverse osmosis filters typically come with everything you need to install and use it. This includes fittings, valves, adapters, filters, and a dedicated faucet.
But you can still improve your system by adding certain accessories.
In this 15-minuted buying guide, we explain which accessories are most useful and review the best ones you can buy online.
If you are still shopping around for an RO system, read our best reverse osmosis system reviews to find the right one for your needs.
What’s In This Buying Guide?
Table of Contents
Our buying guide covers four categories of RO accessories.
Use this table of contents to jump to the specific accessories you are looking for.
Best Reverse Osmosis Accessories: Summary Table
* Disclosure: links below go to Amazon.com
|RO Accessory||What it Does||Our Top Pick|
|Water quality TDS Meter||Tests TDS levels in water|
(an indicator of filter effectiveness)
|HM Digital DM-1 In-Line Dual TDS Monitor|
|Water test kit||Tests your water for specific contaminants||NovoBlue 14-in-1 Home Water Test Kit|
|UV Filter||Kills or neutralizes bacteria, viruses and other microbes in water||iSpring UVF11A UV Disinfection Water Sterilizer|
|Shutoff valve||Automatically turns off water flow when the reserve tank is full, preventing water from continually draining even when the RO faucet is off.||APEC Water Systems Auto Shut Off Valve|
|Leak stop valve||Automatically shuts off the water if it detects a leak||Express Water Leak Stop Valve|
|Storage tank||Stores purified RO water for easy access when you need drinking water||iSpring T55M 5.5 Gallon RO Storage Tank|
|Non-electric permeate |
|Uses hydraulic power to fill the tank faster and reduce the amount of drain water||Aqua Tec ERP-1000 Permeate Pump|
|Electric booster pump||Increases water pressure to improve RO water flow rate and reduce waste||Aquatec 6800 Booster Pump|
|Refrigerator ice kit||Connects your RO system to the refrigerator ice maker||iSpring ICEK Ultra-Safe Fridge Kit|
|Extra tubing||Allows you to install the RO system in a different location from the sink||NEESHOW 1/4″ Quick Connect Tube Fittings|
|Connectors||Important for connecting tubing to various valves and parts.||NEESHOW 1/4″ Quick Connect Tube Fittings|
|Drain adapter||Allows you to connect the RO system drain line and the dishwasher drain hose to the garbage disposal without drilling into the drainpipe||Watts Premier 164020 DLA-D Drain Line Plumbing Adapter|
|Decorative faucet||Improves the aesthetics of your sink area||Lead-Free Water Filtration Reverse Osmosis Faucet|
Best Reverse Osmosis Accessories: Reviews & Buying Guide
Water Quality Accessories
These include accessories that help you maintain and improve the quality of your RO water.
1. Water Quality TDS Meters
If you are going to choose one accessory from this buying guide, get a TDS meter.
A TDS meter is a simple handheld tool that tells you the level of total dissolved solids (TDS) in your water.
Total dissolved solids are salts and minerals in water. They include healthy minerals such as calcium and magnesium, as well as harmful contaminants such as heavy metals.
A TDS meter tells you how well your RO system is working. A functional RO system should significantly reduce TDS levels in your water, usually below 50ppm. Many RO systems can reduce TDS to less than 10ppm.
To see if your RO system is working as expected, test the tap water and the RO water and compare readings. RO water should have much lower TDS levels.
You can also test the drain water from the RO system. It should have very high TDS readings.
If over time, you notice that the TDS levels in your RO water are going up, it’s usually an indication that it’s time to replace the filters.
That said, there are a couple of important things you should know about TDS meters.
What to look for when choosing a TDS meter
Measurement range: This one is not super important because most TDS meters can measure within an extensive range, usually 0-9990ppm. Your water is unlikely to measure more than 500ppm.
Versatility: Most TDS meters measure more than just TDS levels. They also measure water temperature and electrical conductivity (EC).
Auto-off: To conserve battery life, look for a TDS meter with an auto-off function that shuts down the meter after a few minutes of inactivity.
2. Water Test Kits
If you want to test the quality of your water, a water test kit is the way to go.
Unlike a TDS meter that checks how much stuff is dissolved in your water, a water testing kit checks if specific contaminants are present and in what levels.
You are supposed to use a water test kit before buying a water filtration system. It helps you decide which type of water filter you need to buy – reverse osmosis, active carbon, UV etc.
If you already have an RO system, you can still use a water test kit to make sure that your system is working correctly.
Different kits test different things. So check the specific tests included in kit.
Some of the essential tests include:
As with a TDS meter, take your tap water readings then your RO water readings and compare the two. You should see a big drop or complete elimination of contaminants you’ve found in tap water.
You can also compare the level of specific contaminants in your RO water against the legal EPA limits to determine how safe your water is.
What to look for when choosing a water testing kit
What it measures: Some kits measure only one type of contaminant while others might measure as many as 16. The right choice depends on which contaminants you are concerned about. But a versatile kit with multiple tests is the best choice for most RO systems.
Easy to use: Make sure you get a kit that’s designed for home use by non-professionals. You should have no trouble taking readings and interpreting them.
3. UV Filters
Reverse osmosis does a great job removing microbes from water including bacteria and viruses. A UV filter complements the RO system, neutralizing any microbes that get past the RO membrane.
A UV filter is especially crucial if you are using untreated groundwater since it contains much higher levels of microbes.
A UV filter combined with reverse osmosis provides the best defense against disease-causing microorganisms in your water.
Some RO systems such as the iSpring RCC7AK-UV already come with a UV filter integrated. But most don’t include one.
It’s easy to add a UV filter to your under-sink RO system. Here’s a quick video explainer.
Note that you may need to buy extra tubing. Also, a UV filter requires a 110V/120V outlet under your sink.
What to consider when buying a UV filter
Flow rate: Check the filter’s flow rate requirement. This is the max flow rate at which it can effectively kill bacteria and viruses. For UV filters designed to work with under-sink RO systems, the max flow rate is usually 1 GPM. For whole-house UV filters, it’s usually 12 GPM.
Flow sensor: If the UV lamp stays on all the time, it’ll waste power and the bulb won’t last long. A flow sensor turns the UV lamp on only when there’s water flowing. So when you are not drawing RO water from the faucet, the bulb stays off.
These accessories will improve your RO water efficiency and reduce the amount of water that’s wasted.
1. Shutoff Valve
A shutoff valve automatically shuts down water flow when it detects the tank pressure to be two-thirds of incoming water pressure (an indication that the tank is full).
If water kept flowing after the tank has filled up, all of it would go down the drain.
If your RO system makes a gurgling sound even when you are not drawing any water from the RO faucet, it probably has this problem.
Installing a shutoff valve will prevent water wastage when the RO system is not in use.
It’s easy to add an automatic shutoff valve to your RO system. Most have quick-connect fittings so you just need to push the tubing in.
What to consider when buying a shutoff valve
Size: You don’t have to obtain a shutoff valve from the company that makes the RO system. You can buy from any brand, but make sure it’s compatible with your RO system. Most RO filters use ¼” tubing. Look for a shutoff valve with compatible ¼” quick connect fittings.
2. Leak Stop Valve
A leak stop valve ensures that you never come home to flood under your sink. Most RO system leaks go unnoticed, gradually worsening over time.
By the time you realize there’s a problem, your under-sink space is flooded with possible water damage.
A leak stop valve uses a leak detection pad to detect moisture on the floor under the sink. If the pad absorbs any water, it expands, and the valve shuts the water flow automatically just in case it is a leak.
It is easy to add a leak stop valve to your RO system. You are supposed to splice it into the feed water line running from the feed water valve to the RO system.
Screw the leak stop valve against the floor under the cabinet to allow the expansion pad to detect moisture if there’s a leak.
Most leak stop valves have ¼” quick connect fittings. So you just need to push tubing from the feed water valve into the inlet and another to the RO system in the outlet.
Here’s a quick installation video.
What to consider when buying a leak stop valve
Size: Since most RO systems use ¼” tubing, look for a leak stop valve with ¼” quick connect fittings.
Tubing: Some leak stop valves come with the extra tubing you need to install it. With others, you have to buy additional tubing. Note that if your feed line is sufficiently long, you can do without any extra tubing. Just cut the feed line and insert each cut end into the quick connect fittings of the leaks top valve.
Extra pads: You can only use a leak detection pad once. Once it stops a leak, you have to put in a new pad. Most leaks top valves come with 2-3 replacement pads.
3. Storage Tank
Most under-sink reverse osmosis systems come with a 4-gallon pressurized tank with a usable capacity of 3.2 gallons.
That’s enough to provide on-demand drinking water to most families.
But if you have a large family or use RO water for more than just drinking, it may run out sometimes, requiring you to wait for the tank to fill up again.
If you’ve experienced this, we recommend upgrading to a bigger storage tank.
Size options include 5.5 gallons, 9 gallons, 11 gallons, 20 gallons, and 40 gallons. The right size depends on how much RO water you consume every day.
Note that RO systems have a maximum daily output capacity. It ranges between 50GPD for cheaper systems and 100GPD for high-output systems.
So don’t expect the RO system to fill tank after tank with purified water.
Something else to note is that higher capacity means a bigger tank. Make sure you have space under your sink to fit the tank, either upright or on its side.
What to consider when buying a storage tank
Capacity: Depends on your daily consumption. Options range from as small as 1.2 gallons to as much as 53 gallons.
Build quality: Get a well-constructed tank that will last for long without leaking. Also, the interior should be made with food-grade materials to keep your water safe.
Ball valve: Check if a ball valve is included. If it’s not, you have to buy a new one or use the valve from your old tank.
4. Non-electric permeate pump
One of the limitations of reverse osmosis systems is the high amount of water that goes down the drain.
This ‘waste’ water is useful because it washes the filters and carries impurities away. But it significantly reduces RO system efficiency.
An easy and cheap solution is installing a permeate pump.
A permeate pump uses the power of brine water (the water going down the drain) to reduce the amount of back pressure from the pressurized reserve tank.
Normally, the RO system has to push purified water against back pressure to fill the tank. This causes the tank to fill slowly and a lot of water to go down the drain.
By reducing back pressure, the tank fills faster, and there’s less brine water going down the drain (higher system efficiency).
An RO system without a permeate pump typically has a waste to pure water ration of 3:1 or 4:1. With a permeate pump, efficiency increases to a ratio of 2:1.
What to consider when buying a permeate pump
GPD rating: Check that the permeate pump is rated for your system’s output. Permeate pumps have a range of daily water output they operate within.
Compatibility: Check that the permeate pump comes with ¼” fittings since your RO system likely uses ¼” tubes.
5. Electric Booster Pump
An electric booster pump offers the same advantages as a permeate pump. It reduces the amount of brine water flushed down the drain and fills up the reserve tank faster.
It has another big advantage you won’t get with a permeate pump: a higher flow rate out of your faucet.
If you are struggling with water flowing in a trickle from the RO faucet, the likely problem is the water pressure in your home.
RO systems operate best at pressures between 60 psi and 80 psi. If your home water pressure is below 50 psi, the RO faucet will produce purified water in a slow trickle.
A booster pump uses electric power (not hydraulic power like a permeate pump) to increase the pressure of water going into the RO system.
This reduces wastage, increases tank fill-up time, and increases faucet water pressure.
Unlike a permeate pump, a booster pump needs to be plugged into a power outlet. So you may need to call an electrician to retrofit the space under the sink and add an outlet.
What to consider when buying a booster pump
GPD rating: As with permeate pumps, booster pumps are rated for specific output ranges. Check the minimum and maximum GPD requirement for the booster pump to make sure it is compatible with your RO system.
1. Refrigerator Ice Kits
If you are going to be drinking purified water, you should also make sure you are using contaminant-free ice.
Your RO system can supply water both to a dedicated faucet as well as your refrigerator or icemaker.
A refrigerator ice kit allows you to connect your RO system to the refrigerator. The ice kit consists of tubing, a shut-off valve, and connectors.
You connect the fridge kit to the line that takes purified water to the RO faucet. Cut the tubing and attach the cut ends to the included Tee connector.
Run tubing from the connector to the fridge with the shut-off valve installed somewhere along the line.
If your fridge has a water dispenser, you can connect the reserve tank under your sink directly to the fridge using the ice kit. This eliminates the need to install a dedicated faucet on your sink.
If you use a dedicated icemaker, you can also run water from the RO system to it. Ice made with purified RO water is odorless, clearer, and, most importantly, safer for your family.
Note: When you install a refrigerator ice kit, you can remove the water filter in your fridge. The water coming is already filtered.
What to consider when buying a refrigerator kit
Tube length: Check that the included tubing can cover the distance between the RO system and the refrigerator. Otherwise, you’ll need to buy extra tubing.
Build quality: Check that the parts are well made and are BPA-free. A good quality refrigerator kit should serve you well for many years.
2. Extra Tubing
Some RO system upgrades may require extra tubing. For instance, installing a refrigerator kit, adding a booster pump, or installing a UV filter.
Your RO system’s manufacturer likely sells extra tubing. We recommend ordering from them to ensure compatibility.
But any tubing that’s the same size as your current one will work fine. Just make sure it’s of good quality and BPA-free.
What to consider when buying extra tubing
Size compatibility: Most RO systems use ¼” tubing. Get the same size when buying new tubes.
Length: The length of the tube depends on your needs. Refrigerator ice kits require longer tubing than a permeate pump. You’ll also need long tubing if you want to install the RO system away from the sink.
4. Drain Adapters
The usual way to connect an RO system to the drainpipe is by using a drain saddle. But this requires drilling into the pipe.
A drain adapter is much easier to use since you don’t need to cut or drill anything. Just connect it to the garbage disposal.
A drain adapter has inlets for both the dishwasher and RO system drain water. It is easy to install, and most adapters can accommodate different sizes of dishwasher hoses.
You can also use a drain adapter without a dishwasher. Connect the adapter to the garbage disposal and connect the RO drain tube to the smaller inlet on the adapter.
The most important thing to check when buying a drain adapter is the size. Make sure it is compatible with your garbage disposal as well as your dishwasher drain hose.
All under-sink RO systems come with a faucet. But they are usually basic chrome-finished faucets. If you are looking for a more high-end and unique faucet, there are plenty of options available online.
When upgrading your faucet, get one that has the same connector size as your old one to ensure you won’t have any problem connecting your RO system to the new faucet.
It should also be lead-free.