Preventing and Fixing Leaks
in John Guest Style Quick Connect Fittings

Pure Water Products, LLC

Box 2783, Denton, TX 76202 | (940) 382–3814 | pwp@pwgazette.com

Changing the O-ring
inside JG-style fittings

First, remove the collet by pulling it out with your fingers. No special tools required.

Inside a John Guest Fitting. (The O-ring is the black, rubbery part inside.) In this picture, the collet has been removed.

With a thin-bladed tool, like a small screwdriver or toothpick, reach in and pull the o-ring out of its well.

To replace the o-ring, reverse the procedure. Put the new o-ring into the well, tamp it into place with the end of a piece of tubing, then push the collet back into place.

Mur-lok Fittings

At left, a transparent Mur-lok, showing the position of the white collet and the black O-rings. Mur-lok fittings have two O-rings. John Guest fittings have one.

(Mur-lok fittings are sold in black and white. The transparent housing was made only to illustrate.)

It’s rare to have a major leak in a quick connect fitting, but as fittings age, o-rings deteriorate and small drips sometimes develop. Certain chemicals in water, particularly chloramines, can erode o-rings and cause leaks. Leaks also can result from improper installation in which a tube is pulled sharply to one side. This stress flattens the o-ring over time and causes a leak to develop.

If a quick connect fitting leaks, there is usually no reason to replace the entire fitting. Replacing the o-ring is easier and less expensive. You don’t have to remove the fitting from the unit to replace the O-ring.

Here’s How to Replace O-Rings in a water filter fitting

(These instructions show repair of a John Guest fitting. Mur-lok fittings are repaired in exactly the same way, but you'll be replacing two O-rings rather than one. See the picture of a Mur-lok double O-ring fitting below.)

1. Turn off the inlet water and open a faucet downstream of the unit to relieve all pressure. (If it’s an RO unit, it’s also best to close the valve on top of the storage tank.)

2. Remove the tube from the fitting by pressing inward on the collet and simultaneously pulling the tube out of the fitting.

3. Remove the collet from the fitting. Just grasp it with your fingernails and pull it out.

4. Use a thin bladed screwdriver, a match stick, a toothpick, tweezers, or some other thin tool to pull the o-ring out of the fitting. Don’t damage the fitting. (Don’t worry about the o-ring. You're going to throw it away.) John Guest fittings have a single o-ring. Mur-lok fittings have two.

5. Put the new o-ring into the fitting and push it into position with the end of the tube itself. (Don’t use a sharp tool. Avoid damage to the o-ring.) The o-ring should be pushed in so that it stands against the back wall of the fitting.

6. When the o-ring is in place, reinstall the collet by simply pushing it back into the face of the fitting. If the o-ring is slightly out of position, inserting the collet will fix it. You normally won’t need to replace the collet, but it doesn’t hurt.

7. Trim 1/2" or so off the end of the tube to give the fitting a new surface to grip. Get a good square cut on the tube. Insert the tube until you feel it hit the bottom of the fitting, then turn the water back on.

Quick Connect Fitting Supplies.
O-rings, collets, Locking Clips, Release Tool.

We stock the common sizes — 1/4" and 3/8" — of O-rings, collets, and locking clips. The rings are Mur-lok brand, but they interchange with John Guest fittings and, we suppose though we don’t promise, other brands of quick connect fittings as well. We also have collets in the same sizes. It usually isn’t necessary to change collets when O-rings are changed, but if you want them, we have them. As for locking clips, we’ve seen no evidence that they make fittings any safer, and we don’t use them ourselves, but if you want them, here they are. We even have a Mur-lok release tool (which works on John Guest as well), although you don’t really need it in most cases. We’ve found it handy for fittings in hard to reach places, like faucet stems.

Standard O-rings are made of EPDM rubber. This is what you normally get when you purchase a new fitting. The Mur-lok EPDM O-rings below are an NSF/ANSI Certified Component.

Repair Parts for Quick Connect Fittings.

Here are the basic parts you need to repair quick connect fittings. These are top quality Mur-Lok parts, but they work with John Guest fittings and probably with other brands of quick connects, although we haven’t tried them all. The replacements are sold in six packs. Please, don’t call and ask us to sell you a single o ring. Remember that a six pack of 0 rings will allow you to fix six leaky John Guest fittings but only three leaky Mur-Loks. That’s because Mur-Loks have two O Rings.

You usually don’t need to replace the collet to fix a leak, but we have them in case you want to replace them. The red color will tell you that you’ve already fixed this fitting once. We don’t use the locking clips ourselves, but we’ve got them if you're committed to safe plumbing. The Mur-Lok release tool is usually unnecessary, but if you have a stubborn fitting in a hard-to-reach place, you'll be glad you have one.

Note that there’s a hefty volume discount on all these items.
Note, too, that we pay shipping.

If you don’t want to fix a fitting but to replace it entirely,
Quick Connect Fittings are sold on our fittings page and our RO Parts page.

We Pay Shipping on every item on our site.

Packs sold on this page have a quantity discount of 20% off two, 35% off three or more.

Part #	Description	Quantity	Price
QC044	Replacement Collet for 1/4" Quick Connect Fitting. Red.	Six Pack	$6.00
QC045	Replacement Collet for 3/8" Quick Connect Fitting. Red.	Six Pack	$6.00
OR910	Replacement O Ring for 1/4" Quick Connect Fitting. EPDM.	Six Pack	$4.00
OR911	Replacement O Ring for 3/8" Quick Connect Fitting. EPDM.	Six Pack	$4.00
QC048	Locking Clip for 1/4" Quick Connect Fitting. Black.	Six Pack	$4.00
QC049	Locking Clip for 3/8" Quick Connect Fitting. Black.	Six Pack	$4.00
QC999	Mur-Lok Release Tool. For easy release of all Quick Connect Fittings. Fits 1/4", 3/8", 5/16", and 1/2" Fittings.	Each	$3.00