Our beloved universal nut-lock fittings have gotten a makeover. The new design has improved performance and user-friendliness that'll make installation a breeze, but here’s the plot twist - they’ve decided to do everything the opposite way from their predecessor. Confused? So were we!

Understanding Universal Nut-Lock Fittings

Frustratingly, drip irrigation manufacturers make multiple sizes of tubing that are all referred to as ½” or ⅝” in diameter, and they all use different fittings. Universal nut-lock fittings work with all three sizes of ½” (or ⅝”) poly tubing - .620 OD “green stripe”, .700 OD standard, and .710 OD “blue stripe” - eliminating the guessing game when you can’t figure out what size your ½” tubing is.

Components of Universal Nut-Lock Fittings

DIG’s Universal NUTLOC™ Drip Fittings are comprised of three main parts: the nut, the barb, and the base. The barb is connected to the base of the fitting and is designed to be inserted into the tubing. The nut then screws down over the nut and tubing to help hold it in place.

Both the old-style and the new-style universal nut lock fittings have these same components, but they are used differently. Using the old-style fittings involved removing the nut from the base and putting it over the tubing, then putting the tubing on the barb, and finally screwing the nut down over the barb and tubing. The new-style fittings work in exactly the opposite manner.

Using the New-Style Universal Nut-Lock Fittings

Step 1- Ensure that the nut is threaded all the way down against the base of the fitting to expose the barb fully. Do not unscrew the nut from the fitting and take it off

Step 2- Push the tubing over the barb. Don’t overthink it: as long as the tubing is comfortably over the barb, you’re fine

Step 3- Screw the nut down over the tubing and barb to secure them in place. To do this, twist the nut as if you were going to take it off the fitting.

Step 4- To detach the tubing, just reverse this process: twist the nut down against the base of the fitting, then wiggle the tubing until it slides off of the barb.

Simple! Need a visual? Don’t worry, us too. Check out this video:


Drip irrigation systems can be confusing to use, especially if you’re new. The universal nut lock fitting is designed for ease of use, and the new-style fittings are much easier to use and more secure than the old-style fittings. While we can’t tell you why DIG decided to make their new fitting work in exactly the opposite way as their old fitting, we can at least explain how to use one. Looking for more products from DIG? Check out our DIG Irrigation products at The Drip Store. Your plants will thank you - not literally, but in their own leafy ways. Have any product queries or do you want to know more? Reach out to us today!