What Are Channel Locks Used For? | The Pliers Every Homeowner Needs

Channel locks are adjustable pliers built for gripping round, irregular parts like pipes, nuts, and fittings — the go-to tool for plumbing repairs.

Whether you’re a seasoned DIYer or a first-time homeowner, the moment a sink starts leaking or a showerhead needs swapping, the tool you’ll reach for is a pair of channel locks. These heavy-duty pliers solve the problem of getting a strong, adjustable grip on round and oddly-shaped parts that ordinary wrenches can’t handle. Their slotted, tongue-and-groove design lets the jaws open to several widths, so one pair handles everything from a tiny hose connection to a bulky drain fitting. They are the workhorse of plumbing repairs, and understanding what they do — and what they don’t do — will save you time, money, and a few scraped knuckles.

What Exactly Are Channel Locks?

Channel locks are a type of pliers with adjustable jaws that lock into place, officially known as tongue-and-groove pliers. The name “Channel-Lock” is actually a brand name — Channellock — that has become the generic term for this style of tool, much like “Kleenex” for tissues. The design features two handles connected by a pivot that slides along a set of grooves, letting you widen or narrow the jaw opening to match the size of whatever you’re gripping. This mechanism gives them a powerful, slip-resistant hold on round or irregular surfaces.

While they’re often called water pump pliers in other parts of the world, in the U.S., “channel locks” is the standard slang. The most common sizes you’ll see are 6-inch, 10-inch, 12-inch, and 16-inch models. For most household jobs, a 10-inch or 12-inch pair is the go-to size — big enough for most plumbing fixtures, small enough to fit under a sink.

What Are Channel Locks Used For? The Core Tasks

The short answer is that channel locks are for gripping, turning, holding, loosening, and tightening round or irregular parts. Unlike a standard wrench, which needs flat, parallel sides, channel locks bite into curves and odd angles. Here’s where they shine:

• Sink drain slip nuts: These plastic nuts under your sink are round and often stuck. Channel locks grip them firmly without slipping off.
• P-trap parts: Removing a clogged P-trap is the classic plumbing DIY task, and channel locks are the only tool you need to break those fittings loose.
• Hose connections: From garden hoses to washing machine supply lines, these fittings need a strong grip to tighten or loosen.
• Showerheads: Swapping out an old showerhead often requires breaking a stubborn, corroded connection. A pair of 10-inch channel locks does the job in seconds.
• Holding one part while turning another: When you need to keep a pipe from spinning while you turn a nut, the locking grip of channel locks is perfect for the job.

They’re also useful for water-heater fittings, drain fixtures, and any other round or hard-to-reach plumbing part. They work because the jaws can be adjusted wider than the part, then locked into a groove so they bite evenly. If the grip feels too loose or too tight, simply reposition the pivot to a different groove.

The Big Limitation: When NOT to Use Them

For all their versatility, channel locks have one significant drawback: they can scratch and mar surfaces. The aggressive, toothed grip that makes them so effective on pipe will also chew up chrome, brass, or painted finishes. If you’re working on polished fittings, a strap wrench or a rubber-jawed tool is a safer choice.

Similarly, for flat-sided nuts and bolts, a standard adjustable wrench is the better tool. It provides a cleaner grip without damaging the fastener’s corners. And for precision work, where you need exact torque, channel locks are too clumsy. They’re built for power and grip, not finesse. Using too small a pair on a large drain fitting is another common mistake — it reduces your leverage and increases the chance of slipping, which leads to skinned knuckles.

They even sell ready-made sets, like the 3pc Tongue & Groove Pliers Set, which covers most household needs in one purchase. If you’re outfitting a toolbox from scratch, that’s a solid starting point.

How to Use Them Like a Pro

Using channel locks correctly is simple, but there is a technique. First, adjust the jaws so they’re slightly wider than the part you’re gripping. Slide the pivot into a groove so that when you squeeze the handles, the jaws bite evenly on the surface. Then, grip the part and turn — or hold it steady while another tool does the turning.

If you’re facing a stuck fitting, try repositioning to a different, tighter groove. A snugger bite gives you more control and less slipping. The best angle is to keep the tool perpendicular to the part, using the longer handle for maximum leverage.

When you’re ready to gear up, our tested roundup of the best channel locks for plumbing can guide you to the right pair.