---
product_id: 10543007
title: "John Guest3/8\" One Way Check Valve RO Reverse Osmosis Water Filter NSF Certified"
brand: "john guest"
price: "€ 28.58"
currency: EUR
in_stock: true
reviews_count: 10
url: https://www.desertcart.pt/products/10543007-john-guest3-8-one-way-check-valve-ro-reverse-osmosis
store_origin: PT
region: Portugal
---

# NSF certified 3/8" size One-way flow John Guest3/8" One Way Check Valve RO Reverse Osmosis Water Filter NSF Certified

**Brand:** john guest
**Price:** € 28.58
**Availability:** ✅ In Stock

## Summary

> 💦 Flow with Confidence: The Ultimate Check Valve for Pure Water!

## Quick Answers

- **What is this?** John Guest3/8" One Way Check Valve RO Reverse Osmosis Water Filter NSF Certified by john guest
- **How much does it cost?** € 28.58 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.pt](https://www.desertcart.pt/products/10543007-john-guest3-8-one-way-check-valve-ro-reverse-osmosis)

## Best For

- john guest enthusiasts

## Why This Product

- Trusted john guest brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Compact Design:** Perfectly sized at 3/8" for easy installation in tight spaces.
- • **Certified Quality:** NSF certified for your peace of mind and safety.
- • **Durable Construction:** Built to last, ensuring long-term reliability in your water system.
- • **Effortless Water Flow:** Experience seamless filtration with our one-way check valve.
- • **Hassle-Free Maintenance:** Designed for easy cleaning and upkeep, keeping your water pure.

## Overview

The John Guest 3/8" One Way Check Valve is a high-quality, NSF certified component designed for reverse osmosis water filtration systems. Its compact size and durable construction ensure reliable performance and easy installation, making it an essential addition for anyone serious about water quality.

## Description

John Guest3/8" One Way Check Valve RO Reverse Osmosis Water Filter NSF Certified

## Features

- Part #: 3/8SCV

## Images

![John Guest3/8" One Way Check Valve RO Reverse Osmosis Water Filter NSF Certified - Image 1](https://m.media-amazon.com/images/I/51VJcnslc0L.jpg)
![John Guest3/8" One Way Check Valve RO Reverse Osmosis Water Filter NSF Certified - Image 2](https://m.media-amazon.com/images/I/51c0BDDjxpL.jpg)

## Customer Reviews

### ⭐⭐⭐⭐⭐ 







  
  
    Lose that annoying gurgle that air gap R-O filter faucets make
  

*by J***R on Reviewed in the United States 🇺🇸 on January 21, 2016*

I just replaced our now 15 year old kitchen sink. I wanted something new and more modern looking than the builder installed Ivory colored double bowl. I went with a large single bowl stainless steel sink. I added two soap dispensers and a brand new stainless steel faucet for our Reverse Osmosis water filter. I pretty much had three initial goals in mind for this project. (turned into 4).What I wanted..1. Simply the plumbing under the sink (currently it's really jam packed down there).2. Combine the RO filter's  waste water with the dishwasher exhaust.3. Eliminate that annoying gurgling sound that an air gap faucet makes.4. Install a nicer RO faucet.So going with a single bowl sink definitely makes a world of difference. Because there is no divider the usable sink space is massive. Underneath the fact that you only have one drain also simplifies connections. I used a 
  
Watts Premier 164020 DLA-D Drain Line Plumbing Adapter







  
  
     to allow me to connect my dishwashers output to the unused side input on my Waste King disposal unit. I used this back-flow preventer to eliminate any  possibility that dirty water coming from the dishwasher or the compactor can work it's way back into the reverse Osmosis unit.I will point out that in some areas an air gap is required (by code).  I personally do not really care about that.  In my situation the RO filters waste water enters the disposal at a very high point and drains a good 10 plus inches before the trap so there is more than enough room there to eliminate any problems. This device in reality is just insurance and at $10 it's cheap insurance.The reasons for doing what I did were numerous. First There is a much wider range of styles of non air gap faucets available out there, I was able to find a really nice stainless steel unit that matched my main faucet. Secondly  by choosing a non air gap faucet you totally eliminate any noise that the air gap produces, basically the RO filter becomes a totally silent appliance.All in all this was a great purchase. It works great, it's simple to install and it was cheap.I hope that this review is helpful. If you have a question or concern please feel free to post it and I will try to answer you within 24 hours.

### ⭐⭐⭐⭐ 







  
  
    Good little sucker
  

*by J***S on Reviewed in the United States 🇺🇸 on June 2, 2022*

I use this to replace the valve on my water aeration system. The check valve is fine and it does not leak however when the system is running and it's sucking air through it and makes an annoying vibrating noise that the old one didn't make but at least it doesn't leak

### ⭐⭐⭐ 







  
  
    Works as advertised
  

*by K***R on Reviewed in the United States 🇺🇸 on November 8, 2022*

Delivery was a day later than originally expected. Product works fine. Installed to convert an air gap reverse osmosis water filtration system to non air gap configuration. Check valve ensures no flow back contamination to RO filter system & tank in the event the waste line plumbing clogs.

## Frequently Bought Together

- John Guest 3/8SCV 3/8" Push Fit Single Check Valve, Non Return Valve (Speedfit)
- John Guest PPSV041212WP Plastic Push Shut Off Valve, White, 3/8 in. Tube OD
- John Guest 15mm x 3/8" Straight Connector

---

## Why Shop on Desertcart?

- 🛒 **Trusted by 1.3+ Million Shoppers** — Serving international shoppers since 2016
- 🌍 **Shop Globally** — Access 737+ million products across 21 categories
- 💰 **No Hidden Fees** — All customs, duties, and taxes included in the price
- 🔄 **15-Day Free Returns** — Hassle-free returns (30 days for PRO members)
- 🔒 **Secure Payments** — Trusted payment options with buyer protection
- ⭐ **TrustPilot Rated 4.5/5** — Based on 8,000+ happy customer reviews

**Shop now:** [https://www.desertcart.pt/products/10543007-john-guest3-8-one-way-check-valve-ro-reverse-osmosis](https://www.desertcart.pt/products/10543007-john-guest3-8-one-way-check-valve-ro-reverse-osmosis)

---

*Product available on Desertcart Portugal*
*Store origin: PT*
*Last updated: 2026-03-14*