What is the best temperature to brew coffee?
According to the SCAA, the optimal water temperature for coffee is 92 - 96C (197.6 - 204.8F) for 90% of the contact time.

Is water important?
It is quite simple: Coffee is at least 98% water. The higher the quality of water, the higher the quality of the cup. Many people use filtered or bottled water for their coffee. There is a difference. Fortunately, some of the newer, more expensive coffee pots come with small, replaceable charcoal filters built into the machine. If at all possible don't use distilled water. It is missing minerals that makes water pleasing to drink.

Quality of coffee
The quality of a brew depends on the following factors (in no particular order): * Time since grinding the beans. * Time since roasting. * Cleanliness with brewing equipment. * Bean quality (what crop, etc.). * Water quality. Fact: If you are buying "good" coffee, bean quality is the least important of these factors. The best bean will taste bad if any one of these other characteristics is out of place. Not all beans are equal but the other 4 keys to quality will even the field. I will take a lesser coffee that has been freshly roasted and ground any day to any month old preground coffee no matter how good it was when it was fresh. Fact: A coffee can in the supermarket often contains major debris and will be stale, so be careful when you choose. (See note below). Fact: Once you have freshly roasted and ground coffee, filtered water and equipment free of oil residues from the last brew, quality of beans makes a huge difference. NOTE: A coffee can in the supermarket often contains a blend of Arabica and robusta beans while most coffee houses sell only arabica beans. Arabica beans are usually flavor rich, while robusta beans have more caffeine, less flavor and are cheaper to produce. When you buy coffee, whether in a coffee house or in a supermarket, you want to get 100% arabica, except for espresso blends, which may be a combination of both. My personal experience says that a 100% arabica espresso blend is better but many people (including many Italians) will disagree on this point, so go with what you like. For freshness, in a coffee house it is better to buy popular blends that move fast, while in a supermarket vacuum packaged containers with expiration date are your best bet although all canned coffee will be stale to some extent. Chances are you will not get truly fresh coffee in a supermarket. This is an absolute fact if it is pre-ground. In a coffee house look for a shop that roasts in-house and ask what was roasted that day. If the person behind the counter does not know, ask to talk to someone who cares about coffee. If no one knows, go somewhere else. As a side note, it should be mentioned that coffee is at its best after 12-24 hours, so you might be interested in day-old coffee if you plan to brew the same day. Also, grind your own coffee. Buying fresh and then having it ground defeats the purpose. Ground coffee only lasts a few hours or one day at the most.