How do I adjust the pressure on my espresso machine?

The standard for modern espresso brewing is 9 bars of pressure, which provides the ideal balance for extracting oils and solids from the coffee puck. Many home machines come from the factory set to higher pressures—sometimes 12 to 15 bars—to compensate for inconsistent grinds or poor tamping. While these higher pressures can still produce coffee, they often lead to harsh, over-extracted flavors and increased channeling.

To adjust the pressure, you must locate the Over-Pressure Valve (OPV). This component acts as a relief valve, diverting excess water back into the tank or drip tray once the target pressure is reached. On many machines, this is an adjustable screw. By tightening the screw, you increase the pressure; by loosening it, you decrease it. Because this requires opening the machine, it is essential to ensure the unit is unplugged and cool before beginning.

Before you start turning screws, verify your current pressure using a portafilter pressure gauge. Without one, you are essentially guessing. Once you have a baseline, make small, incremental adjustments. It is easy to overshoot your target, so take your time. If your machine does not have an adjustable OPV, you may be limited to controlling pressure through your grind size and dose, though some enthusiasts choose to install aftermarket kits.

In practice, adjusting your machine to 9 bars can significantly improve the clarity and sweetness of your shots. It makes the machine more forgiving of minor errors in puck preparation and helps prevent the bitter, burnt notes often associated with high-pressure extraction. If you are uncomfortable working with the internal components of your machine, consult a professional technician to avoid damaging the pump or electrical systems.