I drink loads of coffee. It's normal where I come from. In Finland, Sweden, Denmark and The Netherlands more than 10 kg of coffee is consumed per person per year on an average in each of these countries. I'd be pulling vup the average if I wasn't outside the country most of the time.
I'd havea mug of coffee with breakfast, another at work before start of the workday. Thereak at morning break, coffee-break, lunch, afternoon coffee-break. When I get home from work, after dinner and with my evening coffee and cake - but only one mug then as I'd have to sleep unless it's Friday and Ill have another mug. That should amount to 2 liters.