Key takeaways
- The water knot (tape knot) joins flat webbing or ties it into a loop (a sling).
- It's an overhand knot in one end, retraced by the other end of webbing.
- It's the standard knot for webbing, used for slings and anchors.
- It can slowly work loose — leave long tails, dress it well, and check it regularly.
This is general educational information, not instruction. Knots are life-critical — learn and verify them hands-on with qualified instruction.
What the water knot is
The water knot (or tape knot) is the standard knot for joining two ends of flat webbing or tying webbing into a loop (a sling), formed by tying an overhand knot in one end and retracing it with the other. It’s the go-to knot specifically for webbing, as opposed to rope or cord.
How it works
Tie a loose overhand knot near one end of the webbing, then take the other end and retrace the overhand in reverse so the two strands lie parallel through the knot, and tighten it down. The result is a secure join — provided it’s dressed neatly (no twists) and left with adequate tails.
To make a sling from tubular webbing, a climber ties a water knot — overhand in one end, the other end retracing it — leaves several inches of tail on each side, dresses it flat, and checks the tails each time they use it, since the knot can creep loose over time.
Cautions
The water knot is reliable when properly tied, but it’s known to slowly work loose under repeated loading, which can dangerously shorten the tails. So leave long tails, dress and tighten it well, and inspect it regularly. For critical, permanent slings, many climbers prefer sewn (bar-tacked) slings to avoid the risk. It’s one of several climbing knots, used for anchors alongside the double fisherman’s for cord.
The bottom line
The water knot is the standard way to join flat webbing or tie it into a sling — an overhand knot retraced by the other end. Reliable when properly dressed with long tails, it's known to slowly creep loose under repeated loading, so it demands long tails and regular inspection. For critical, permanent slings, many climbers prefer sewn webbing to avoid the risk entirely.
Frequently asked questions
What is a water knot used for?
The water knot (or tape knot) is the standard knot for joining two ends of flat webbing, most commonly to tie a length of webbing into a closed loop (a sling) for use in anchors, extending protection, or slinging features. It's the go-to knot specifically for webbing, as opposed to rope or cord.
How does the water knot work?
You tie a loose overhand knot near one end of the webbing, then take the other end and retrace (follow) the overhand knot in reverse so the two strands lie parallel through the knot, and tighten it down. The result is a secure join, provided it's dressed neatly (no twists) and left with adequate tails.
Is the water knot safe, and what should you watch for?
It's reliable when properly tied, but the water knot is known to slowly work loose over time, especially with repeated loading and unloading, which can shorten the tails dangerously. So you should leave long tails (several inches), dress and tighten it well, and inspect it regularly — re-tightening or retying if the tails are getting short. Many climbers prefer sewn (bar-tacked) slings for critical uses to avoid this risk.
Sources
- Climbing knots & webbing — American Alpine Club
- Knots & rope work — The Mountaineers