How to Replace the Group Gasket on an Espresso Machine When the Portafilter Leaks

By James Whitfield · 5 October 2026 · Updated : 5 October 2026

Quick answer : A group gasket is the ring of rubber or silicone sitting in the group head, and its whole job is to seal the rim of the portafilter basket while the pump pushes water through at about 9 bar on an E61-style machine. Worn gaskets let water escape sideways. If you can see drips around the portafilter during a shot, or the handle has to travel far past 6 o'clock to lock, replace the gasket. It is a cold-machine job with a flat screwdriver and a gasket pick.

The essentials

Watch the handle: an empty portafilter should lock near 6 o'clock, and a handle that needs to go much further is asking for a new gasket.
Dripping at the portafilter rim is a gasket problem. Water from beneath the group between shots, or at the brew lever, is a different repair.
E61 groups usually take 8.5 mm (common factory fit) or 8 mm (thinner). Caliper the old ring before ordering.
Quoted lifespans run from 6 to 18 months, depending on how hard the machine works.
Wait about two hours after switching off. A brass group stays hot far longer than it feels like it should.
New ring: flat side up into the machine, bevel down toward the portafilter. Snug the screen screw, no more.

The 6 o'clock test and other warning signs

Slide an empty portafilter into the group and turn it until it stops. On a healthy machine the handle ends up around 6 o'clock. Needing to go well beyond that to stop water creeping out is the most reliable warning sign, and it appears before a visible leak does. Hardened rubber has shrunk and lost its spring, so the portafilter has to climb further to compress it.

Other signs: a ring that looks cracked, hard or flattened, and beads of water at the rim while the pump runs. The second is easy to blame on the pump, yet the seal is the first place to look.

Heat does the damage. Every warm-up and every shot cycles the rubber through high temperatures, and over months it turns from pliable to brittle. Forcing the handle home makes things worse, so a firm, steady turn is better than a hard slam.

Three leaks that look alike

Drips at the portafilter rim during extraction: the group gasket, which is what this page fixes. It can also be a perfectly good gasket that has popped out of its groove and needs pressing back in.
Water weeping under the group head between shots: usually a tired group valve, a job for a proper service.
A drip at the brew lever pivot: the cam o-rings.

If you are unsure, give the group a backflush first. Coffee residue in the screen and valve can cause symptoms that look like failed parts, and cleaning costs nothing.

Buying the right ring

The group that most home machines copy, the E61, was designed by Ernesto Valente for Faema and launched in 1961. Its gasket comes in two common thicknesses, 8.5 mm and 8 mm. Rely on a caliper measurement of your old ring, not on a guess, and note that machines from other families, Gaggia, Rancilio or Breville for example, use gaskets specific to their group.

On material, black rubber and silicone both do the job. Silicone shrugs off heat for longer, rubber can feel slightly firmer on the handle. Whichever you pick, a correct fit matters far more than the compound.

Your shopping list is short: the gasket, a wide flat screwdriver, a gasket pick or a small flat screwdriver with taped tip, a microfibre cloth and group-head cleaner.

The job in eight steps

Roughly 20 to 30 minutes of hands-on work once the machine is cold, on any 58 mm group of the usual design.

Power down. Turn the machine off, unplug it and give it about two hours. Opening a hot brass group is how people get burnt.
Take out the portafilter. Remove it, and the drip tray if it blocks your view of the group.
Back out the screen screw. Use the wide flat screwdriver on the centre screw. Lift off the shower screen and dispersion plate and let them soak in group-head cleaner.
Hook the old gasket out. Push the gasket pick into the rubber and pull. Brittle rings come out in pieces, so fish out every bit.
Wipe the groove clean. Run a microfibre cloth around the recess until it comes away spotless. Leftover rubber is the number one cause of a failed repair.
Seat the new ring. Flat side up toward the machine, bevel facing down. Work around the edge with the back of the pick until it is level.
Put the screen back. Refit plate and screen, then tighten the centre screw until firm. No torque value is published by the makers consulted, so avoid cranking it.
Try the lock and run water. Insert the empty portafilter a few times and look for a stop near 6 o'clock. Then flush water through and watch the basket rim.

Some Gaggia-style models hold the shower with a plate fixed by two 5 mm Allen screws, reached from below with the machine lying on its back. The sequence of removing, cleaning, seating and reassembling does not change.

Making the new gasket last

Treat the portafilter gently, since slamming it into the group is a recognised cause of early wear. Wipe the shower screen and rinse the group after sessions, and descale according to your water (our guide on descaling and cleaning an espresso machine covers it). A quick look every three months catches hardening before it turns into a leak.

On lubricant, guidance is split. One maker applies a thin film of food-safe silicone grease to the flat, machine-facing side of a rubber gasket, whereas others advise keeping grease off the sealing surface altogether. Keep it off the face that meets the portafilter, and follow your manual.

If water still escapes after the swap, run through the usual suspects: ring fitted upside down, crumbs of old rubber in the groove, the wrong thickness, a warped basket, or a fault that was never the gasket. On an E61, valves and the mushroom o-ring are normally renewed as a set, which is a job to hand to a technician unless you have stripped a group before.

Frequently asked questions

How often should a group gasket be replaced?

Retailer and maker guides quote anything from 6 to 18 months: about a year for daily home use, sooner on a busy machine. The real signal is a portafilter that locks well past 6 o'clock or drips.

Should I choose an 8 mm or 8.5 mm gasket?

On an E61 group, 8.5 mm is the most common fit and 8 mm the thinner alternative. Measure the old ring and check your machine's part number rather than guessing.

Can I replace a group gasket myself?

Yes, it is routine maintenance. You need a flat screwdriver, a gasket pick or a taped small screwdriver, and a cold machine. A technician is only needed if the leak lies elsewhere.

Why does my portafilter leak with a new gasket?

Common causes are a gasket fitted upside down, a dirty groove, the wrong thickness, a warped basket, or a leak that is not the gasket at all, such as a valve or cam o-ring.

Sources

The procedures, intervals and dimensions on this page come from maker and specialist-retailer technical guides, consulted in October 2026.

Keep reading: Descale and clean an espresso machine · Best espresso machines 2026 · Coffee FAQ