Reverse Osmosis System Check Valve Location | Guide

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If you’re wondering where the check valve of your reverse osmosis system is located in order to clean or replace it, this article is for you.

You’ll typically find the check valve in the same place on all reverse osmosis systems, which makes it easy to find and swap out.

Want to learn more? Continue reading!

Key Takeaways

  • A reverse osmosis check valve must be hooked up directly after the RO membrane.
  • There are generally two ways to connect a check valve: directly to the RO membrane housing (on permeate port), or along the permeate line (before ASO valve).

Reverse Osmosis Check Valve Location – Where Does It Go?

So, where is a reverse osmosis check valve located?

The check valve in a reverse osmosis system is typically connected directly to the reverse osmosis membrane housing – to the permeate water port. This type of check valve often has the form of an elbow.

If your check valve is not directly connected to the RO membrane housing, then it’s located somewhere along the permeate line itself (inline, before automatic shutoff valve). Typically the line must be cut to allow for the installation of the check valve.

This diagram should also help you locate your RO check valve:

reverse osmosis check valve diagram

Other Commonly Used Valves in RO Systems and Their Installation Locations

Several other valves play an important role in the operation of a reverse osmosis system. No matter what specific design you’re using in your home, your system very likely contains all of those valves as well.

Feedwater Valve

The feedwater valve is used to connect the reverse osmosis system to the cold water supply under your kitchen sink (or similar place).

If you are not using a point-of-use RO system but a whole house unit, then the feedwater valve connects directly to the main water line of your house.

ASO Valve

An automatic shuttle valve is important in the operation of a reverse osmosis system, as it prevents the system from working excessively when the storage tank is already full. A common problem reported by owners of reverse osmosis systems is that they sometimes hear the system kicking in even when the tank is full. Usually this can be traced back to a malfunctioning ASO valve.

The ASO valve is located between the last pre-filter stage and the RO membrane inlet, and the RO membrane outlet and storage tank/post-filter.

Flow Restrictor

A flow restrictor is important for ensuring the proper operation of your reverse osmosis system. It accomplishes that by limiting the flow of water passing through the drain line (where it’s located).

Without a flow restrictor, water will naturally make its way to the drain line and will bypass the reverse osmosis membrane almost entirely.

How Under Sink Reverse Osmosis Systems Work

With all that in mind, how does a reverse osmosis system work in the first place? The general idea is quite simple. At the heart of your system, you have the RO membrane. This membrane is semipermeable with very thin pores which only allow water to pass through. Water is pushed against this membrane at high pressure, resulting in all contaminants getting filtered away.

Most reverse osmosis systems also incorporate additional filtration stages to further improve their performance. For example, you might have some pre filtration stages which remove sediments, chlorine, and other contaminants before they reach the membrane. You might also have post filtration stages which finalize the job and perform additional tasks like reintroducing minerals to the water after they have been removed.

If you have any questions about reverse osmosis check valve location please don’t hesitate to leave a comment below!

About the Author Alexandra Uta

Alex is a content writer with an affinity for research and a methodical attention to detail. Since 2020, she has fully immersed herself into the home water treatment industry only to become an expert herself. Alex has been using water filters and similar products for years which has gained her lots of hands-on experience.
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