John Guest style push-fit fittings info & warnings

Admins, not sure where this goes. Stuck it here.

The push-fit fittings that often are used to connect RO/DI units, other water filters, auto-top-up systems, etc., look something like this:

The way it works is you push tubing into the fitting, and when the collar is ‘out’ (slightly away from the body of the fitting) and the tubing is in far enough, it’ll hold it in a watertight fashion.

Hint #1: Be careful. Examine the fittings before you use them to make sure the collar is undamaged. That is, not like this:

You can see that the collar is broken and separated. This might hold, but it might not.

Also, one of the benefits of this fitting style is that they’re removable. You simply push the collar in, and the tubing will pull out. That’s good … except when it pulls out when you weren’t expecting it to (like at 3am).

Hint #2: Only some products that come with John Guest fittings also come with the locking rings. These things are cheap, and excellent insurance. See below, the way they work is after you’ve inserted the tube into the fitting, you slide a piece that looks like a c-clip (or a horseshoe) onto the collar, which hold the collar away from the body of the fitting – which locks the tubing in place, making it much less likely to come loose unintentionally. When you do want to take it apart again, they pull right off.

They’re cheap, 50 for $5 or so.


Good info. I have some of those fittings but decided to go with this style. They are designed to be disconnected and that was what I was looking for. If I needed a bunch of them I would maybe rethink it but for just a couple it seemed worth it to me.

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I recently found some of the clips. Before I knew about them I used a small piece of wire to keep the collar in position. Had one come loose before that. What a mess.

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