How to Use Compression Fittings on 1/2" Polyethylene Drip Tubing

Compression fittings for ½" poly tubing (0.700" OD / 0.600" ID) are common in drip kits but can be confusing. Here's how they work and key tips for leak-free connections.

Anatomy of a Compression Fitting

Typically: a body, a compression nut, a ferrule (split ring), and an O-ring (flat or beveled). The nut compresses the ferrule and O-ring onto the tubing, creating a seal.

Installation Steps

1. Cut tubing square and clean. Cut long; trim incrementally for perfect fit.
2. Slide nut onto tubing (threads facing fitting body).
3. Insert tubing fully into the fitting body until it bottoms out.
4. Hand-tighten the nut, then give ½ turn with pliers. Do not overtighten—plastic fittings crack.
5. If O-ring is beveled, the bevel usually faces the nut (taper toward nut).

Pro Tips

• Keep tubing straight—no kinks or angular stress at the fitting.
• A little saliva or silicone lubricant on the O-ring eases insertion.
• For drip-line compression fittings (barb + nut), just wiggle the tubing in; they're lower pressure.
• Pressure-test before burying. Re-tighten slightly if any weep.

If your kit includes a compression × thread adapter, use it to transition to a barbed fitting for the poly tubing. Always follow the manufacturer's instructions—designs vary.