Should you add oil to pasta water?

A splash of olive oil in the pasta water is one of those habits handed down through families, cookbooks and television. It feels right. It is also mostly a waste of good oil.

What oil in the water does

Oil and water do not mix. When you pour oil into a pan of boiling water, it gathers on the surface in little pools, while the pasta tumbles underneath in the water. So during cooking, the oil barely meets the pasta.

When you drain, the pasta passes through that layer, and some oil clings to it. That thin coating can stop your sauce from sticking to the pasta, which is the opposite of what you want. Sauce should grip pasta, not slide around it.

Nigella Lawson's site gives the same advice: no oil in the water, and a brief stir once or twice during cooking instead.

Why pasta sticks

Pasta releases starch into the water as it cooks, especially in the first few minutes. If the pieces sit pressed together while that surface is sticky, they glue themselves to each other. The fixes are simple:

• Use plenty of water. A big pan of water returns to the boil faster after the pasta goes in, and gives the pieces room to move. That said, you can cook pasta in less water with a little more attention: see cooking pasta in less water.
• Bring it back to a boil quickly. Lid on until the water returns to a rolling boil, then lid off.
• Stir early. Give the pasta a good stir as soon as it goes in, and again a minute or two later. This is when most sticking happens. Long pasta especially: push it gently under as it softens and separate the strands.
• Do not overcook it. Overcooked pasta is softer and stickier. See how to tell when pasta is al dente.

After draining

Most pasta sticking happens after cooking, not during it.

• Get the pasta into the sauce quickly. Better still, lift it straight from the water into the pan with the sauce, with a splash of its cooking water.
• Do not rinse it for hot dishes. Rinsing washes away the starch that helps the sauce cling.
• Keep some cooking water. Starchy pasta water loosens a sauce and makes it glossy. Our page on what pasta water is for covers this.

When oil does make sense

• Pasta for salads. Nigella's site suggests a small drizzle of olive oil after cooking for pasta served cold, to stop it clumping. We agree: toss it while warm, then let it cool.
• Pasta that has to wait. If you must hold cooked pasta before saucing, a little oil tossed through helps keep it separate.
• Fresh filled pasta sometimes benefits from a gentle toss in butter or oil once drained.

In all of those cases, the oil goes on the pasta after cooking, not in the water.

And foaming?

Some people add oil to stop the pan boiling over. A large enough pan and adjusting the heat once the water is boiling do the job more reliably. Turn it down a little to a lively, steady boil.