The importance of correctly ground coffee for Filter Coffee machines

Like London buses nothing for ages, and then two come along at once!

We had an issue today with a restaurant customer of ours who was finding that his filter coffee was tasting very bitter. The immediate reaction might be to check how long he's been brewing it for, how clean is the machine / jugs etc.

However on this occasion we had to hold our hands up and say that we had ground the coffee a little too coarsely. Rather than the water being held by the coffee to allow time for brewing, it was passing through the filter way too quickly. The result a thin, bitter tasting beverage was pretty awful.

From our perspective particularly irritating because we carry out routine tests on our coffee grinders to ensure that extraction levels are correct - clearly something went wrong on this occasion.

The second issue was the total opposite. A domestic customer who grinds his own coffee was finding that he was getting grounds in his cup. He thought that he might be grinding his coffee too fine and that this was passing through the paper. This last point is virtually impossible unless the paper is splitting at the seam.

Actually though he is correct in that by grinding the coffee too fine, he's not actually allowing it to flow away sufficiently quickly and as a result the filter holder is becoming inundated with water and coffee, and then overflowing slightly into his cup / jug.

The interesting point is that in terms of microns, there probably isn't that much difference between the particle size of the coffee that hasn't been quite ground fine enough, and the one that is too fine, but the result in the cup is completely different.

So as for espresso coffee, the correct grind for filter coffee is just as important, it just doesn't get the headlines that espresso coffee gets.