The quality of coffee is determined by several factors. Of course, one of the important factors is the taste of the person that drinks it, but apart from that, there are a few other factors to take into consideration if you want to brew a quality cup of coffee.

In this article I'm going to underline these factors. Also, if you live in U.K., I'm going to give you a few pointers regarding where to buy coffee beans of the best quality. 

So, which are the factors that determine the quality of coffee?

1. The water. It's almost impossible to find pure water, containing only the basic elements (H2O) on a regular basis. Almost everywhere, water contains various other minerals or compounds, in higher or smaller concentrations, which can change its taste properties. As a general idea, water has to be odourless and tasteless. So, unless you have a special filter attached to the kitchen faucet, it's best to use flat water or bottled water. 

2. Time since the coffee beans were ground. In general, to obtain a maximum flavored coffee brew, it's best to grind the coffee beans the moment before brewing. Once ground, coffee will lose its aroma and taste much quickly and in just a couple of days, you can get from a nicely flavored roast, a batch of flavourless, flat brown powder. So, to obtain quality coffee, use only freshly ground coffee beans.

3. The time since the coffee beans were roasted. Coffee beans are not like wine or like cheese. The more they remain in storage, they lose their properties. However, coffee can remain in storage for a long time before it changes its properties, even if its not roasted. 

4. The sterility of the brewing gear. Well, the brewing equipment doesn't have to be exactly sterile to obtain good coffee. It's not medical equipment. However, it must be cleaned periodically. For example, if you're using a mocha pot, it's best to wash it properly after each use. The coffee recipients in any store's coffee machines are never properly cleaned that's why the coffee tasted bad. Plus, the coffee ground might be mixed with major quantities of debris, which may render the coffee undrinkable.

5. The coffee beans quality. There are, obviously, superior and inferior quality coffee beans. If you're not aware which is which, you can ask a coffee supplier. So, it important to select a superior type of coffee beans, properly roasted. Also, it really matters where you buy coffee beans. 

I live in U.K. and this is my recommendation: you can buy coffee beans here. This is the best shop I know to buy coffee online.