The H2O error code indicates a few things:

• It could mean that there is not enough water in the tank for the selected beverage;
• or it could indicate the water tank in not seated properly in the unit and there is air in the circuit.

If the H2O error appears, completely remove the water tank from the unit, reinsert it by firmly pushing it into place, and fill the tank with at least 1.5 liters (50 ounces of water). Turn the unit off and then back on to clear the error. If this does not help, remove the water tank again and reinsert it ensuring it clicks back into place. You may need to try this a few times to clear any air in the line and clear the error.