Plastic Tubing Leak Repair Lifehack

If you have any amount of plastic tubing, like the 1/4 plastic tube used to feed the water fountain on the sink, or the icemaker and water dispenser on the refrigerator, you should get one of these coupling joints, part number PP040WD, PL-3000, SKU 707102. It’ll save you a lot of headache when the plastic tube leaks.

We had a leak under the sink, where the water filter is. This is a really old installation going back around 30 years, and it’s held up, but the plastic pipe keeps breaking every decade.

Here’s the connection to the water supply. Yeah, it’s piercing steel tubing.

So, first, I shut off the water supply, so the leak wouldn’t be so bad.

It wasn’t enough, so I opened up the faucet to relieve pressure. Water dribbled out, and the leak abated.

I tried to fix this leak with Gorilla Tape. The stuff is amazing, but it didn’t seal up this leak.

So, what I did, was cut the leak out:

I just cut it out with scissors. Just try to cut the ends square. My cuts weren’t great, but they worked.

Then I mended the break with the coupling.

There you go: a quick, temporary fix.

Part Two: the more permanent fix

I then went and bought several pieces of plumbing online. John Guest has a valve that fits in between a standard 3.8″ compression supply line, and presents a 1/4″OD push-on fitting.

Since this sink’s water supply doesn’t use the contemporary 3/8″ connections, but the old 1/2 MIP connection, I got two 1/2″ FIP – 3/8″ FIP supply hoses, and a (male-to-male) 3/8″ Compression union coupling.

Here’s an exploded diagram of what I’m making. It’s a supply line, but rigged up with a T valve in the middle.

I hope this all works, and we’ll have a new supply line, with a 1/4″ push-on connection in the middle.

So, I went and bought a union, but it was the wrong threading (called MIP). I think the stuff I got was for flare ends or something. I got the correct one on the second trip:

Unfortunately, they didn’t have a single pack for this, and I ended up getting the five pack. So I have four to sell!

You don’t need the compression fittings, just the union.

This union acts like a “gender changer” on the John Guest valve, so it presents male threads at both ends.

Those ends can go into 3/8″ compression supply connections.

As noted above, I used 1/2″ FIP – 3/8″ FIP supply hoses. That’s an oddball hose, but they have it at HD and other places.

Once connected, this new “supply line” presents 1/2″ FIP at both ends, and the 1/4″ plastic in between, at the T.

Installed, it looks like this:

Once again, the diagram version:

The Actual Ugliness of the Installation

First, I had to shut off the supply as best I could, and cut the old supply line in two, with a hacksaw. I opened the faucet all the way, to relieve pressure, and put a small bucket under the supply, to catch the leaks.

Here are my tools, and what the cut pipe looked like:

Next, I unscrewed the two ends. I had to use both of the wrenches. One held the and on the faucet, and the other, the nut to be freed. At the supply end, one held the valve steady, and the other turned the nut, to free it.

I took the telflon tape and wrapped each of the ends, at the supply valve, and up onto the faucet supply.

I attached the supply rig onto each end, and screwed it down finger tight. Then I used a wrench to add a more of a turn, to seal each end. I start with my fingers, so I don’t cross-thread anything.

Replacing Plastic Hose

Replacing some of the plastic hose was easier. The hose ran from the T to a water filter. There wasn’t anything complicated.

Using a utility knife, I just cut some to length, removed the old hose, and pressed the new hose into place. I cut it to leave a couple extra feet, for slack.

Here’s another photo of the final product. If I were to do anything different, I’d use supply lines longer than 12 inches, and build looser loops.

Parts for Sale

I’ll sell one union with 5 ft of plastic hose, for $5 + shipping. Or put a $10 donation into my

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