O-Ring Sizes for Pressure Washer Quick Connects
The 50-cent part that stops a job
Every quick connect fitting seals with a small o-ring — and when it wears out, the connection leaks, sprays, and loses pressure. It's the most common 'my rig is broken' call we get, and it's usually a 50-cent fix. Keep a handful of spares in the truck and you'll never lose a day to one.
Standard sizes
Pressure washer and hydrovac quick connects follow three standard bore sizes, and the o-rings match:
- 1/4" — most residential-grade guns, wands, and hoses
- 3/8" — the most common commercial pressure washing size
- 1/2" — high-flow rigs and hydro excavation setups
Our Viton o-rings come in all three sizes and outlast standard seals — Viton handles heat and chemical exposure (including bleach and degreasers) that hardens and cracks ordinary Buna-N rings.
How to replace one
- Depressurize the system and disconnect the fitting.
- Remove the old ring with an o-ring pick set — don't gouge the seat with a screwdriver.
- Clean the groove; inspect for scale or damage.
- Lubricate the new ring lightly and seat it evenly in the groove.
Which do I need?
The size matches your quick connect bore — 1/4", 3/8", or 1/2". If you're not sure, text a photo of the fitting to 281-512-5223 and we'll size it. We stock these in bulk in League City, TX — crews grab them by the handful.