Why is my coffee sour?

It may have been poorly roasted. Or – because that definitely doesn’t happen with Mount Hagen coffee – it hasn’t been prepared properly. The mistake is probably the size of the grounds: they are presumably too coarse. Next time, try using finer grounds. But because the amount of coffee, grind size and brew time all play a role, it is a good idea to use the same amount of coffee and pour the water over just as slowly. Otherwise, you won’t be able to compare your results. Incidentally, the same principle applies to preparation with a coffee machine.

If you want to know more about how to make really good coffee, take a look here.