Cutting copper and plastic pipe

Learn to cut copper and plastic pipe cleanly and squarely using a pipe cutter or hacksaw.

CP-01Know your two main toolsA pipe cutter looks like a C-shaped clamp with a small cutting wheel. You tighten it around the pipe and rotate it, and the wheel scores deeper each turn until the pipe parts. A hacksaw is a hand saw with a thin, replaceable blade - it works on any pipe but takes more skill to keep straight. Beginners should start with a pipe cutter on copper, as it does most of the work for you.

CP-02Isolate the water before you cutIf the pipe you're cutting is already connected to the system, turn off the water at the stopcock (usually under the kitchen sink or where the supply enters the house) before you touch it with any tool. Then open the nearest tap and let it run until it stops, to drain the water sitting in the pipe. Expect there to be water in the pipe even if it looks empty - a few hundred millilitres can still soak your cupboard when you cut. If you're cutting a brand new offcut of pipe that's never been fitted, this step doesn't apply.

CP-03Mark a straight, square lineWrap a strip of paper or a length of tape around the pipe so the edges line up perfectly - this gives you a straight line all the way round, which your eye alone can't judge. Draw along that edge with a pencil or marker. A cut that isn't square (not at a true right angle to the pipe) will leave a gap when you try to fit a joint, and joints don't seal well on an angled cut.

CP-04Cut copper pipe with a pipe cutterOpen the cutter, position the wheel exactly on your marked line, and close it until it just grips the pipe - not crushingly tight. Rotate the whole tool around the pipe one full turn, then tighten the adjusting screw a quarter turn and rotate again. Repeat this tighten-and-rotate cycle until the pipe separates. It should feel like the tool is doing the cutting, not you forcing it - if it feels stuck, you've likely over-tightened.

CP-05Cut plastic pipe with a saw or cutterPlastic pipe (often blue or grey, used for cold supplies or waste) can be cut with a fine-tooth hacksaw or a ratchet-style plastic pipe cutter that works like secateurs. Hold the pipe steady - clamp it in a vice or brace it against something solid - and saw or squeeze in one smooth motion rather than sawing back and forth roughly. The classic beginner mistake is letting the saw wander, which leaves a slanted end instead of a flat one.

CP-06Deburr the cut endEvery cut leaves a rough lip or burr on the inside and outside edge of the pipe, even if it looks clean. Run a deburring tool (a small hand tool with a triangular blade) around the inside edge, or use a round file, to smooth it. Skipping this leaves sharp ridges that catch debris, damage rubber seals, and stop the pipe seating fully in a fitting.

CP-07Check the cut is rightHold the pipe end-on and check it looks perfectly round, not oval or squashed - overtightening a pipe cutter can distort copper. Place a set square or the edge of a fitting against the cut face; there should be no visible gap anywhere around the circumference. Run your finger inside the pipe end - it should feel smooth, with no sharp edge or burr left.

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