Instruction: Generate an answer to the question by utilizing the information contained in the document.

Input:
Question: Do you pour  the amount of water you need? Or is there a tank that needs to be filled? Or is there a line that needs to be hooked up to supply water?
Document: Then I found this model directly from Keurig. The non-working Breville has been "retired" and is now sitting in the basement waiting to be sent to its final resting place (not a kitchen counter).The OfficePRO doesn't have the fancy menu system that the Breville had. Instead it has simple indicator lights to tell you it's heating, the water tank needs to be filled, descale, etc. That works for me. The important word here is "works".
Our Keurig arrived a year ago this week. Our overall satisfaction is "5 Star" ... we love the convenience! And we've even found ways to save on our favorite cups, such as buying on-line or buying in bulk at Costco or Sam's.So, what prompted this "less than perfect" review? As I filled the water reservoir this morning, a little groggy and blurry eyed, I realized this (and most) Keurigs are designed favoring the left handed population.
I would have purchased it on Amazon but they were more expensive at the time. I'm glad to see that the Amazon price now matches Staples. Compared to the $249 for the Breville, this was much less expensive.When the coffee maker is first set up, it goes through a priming process in which water is first pumped into the machine from the tank on the side. By the way, the water tank, which holds 48 ounces of water, must be filled manually.
It spit some air and a little water into the tank before running empty. I then reset for an initial prime and watching the water level in the tank, it pulled in a little more water this time. I had to repeat this sequence about 3-4 times and each time it pulled in more water (and drained when the valve was reversed). I knew the boiler was full as it was now pulling in the same amount of water during each drain & prime.
Helpful hint:  the removable water tank had a strong plastic smell; it didn't seem to affect the coffee, but it did affect the tea. I ran the tank through a short dishwasher cycle, using only a small amount of detergent, then rinsed it repeatedly after it came out. Problem solved. Helpful hint two: use filtered water or bottled water for the best taste.The brewer is incredibly fast; it takes a couple of minutes to heat up, then it's ready to go.
These small bladder-style pumps do not like air bubbles in the supply line, whether it's during initial prime or after months/years of use. Clearing the air-lock seems to fix every one of the pump-plagued units that have been repaired from what I've reviewed. My feeling is that if Keurig can implement a fix to keep this condition from occuring on both consumer and commercial-grade models, they would have much happier customers.
It can also be fitted with a water filter, which can help prolong the time between descaling cycles. Also, an LED indicator will let you know when your machine needs to be descaled.
(great for when people are over trying it out one after another!) The one in our hotel room was also pretty noisy as it had to heat up the water each time before preparing to pour your drink, but the OfficePRO heats up the water after you power on the system and doesn't cool it until you power it off.
cup. The brewer works well with the EcoBrew insert and I've been using my own coffee as often as the pre-packaged cups, with good results. Refilling is a cinch, I just pop the top off and pour in fresh water from my filtered pitcher.
UPDATE: Old morning routine - stumble around in the kitchen, tripping over the dogs' beds while I rinsed the coffee pot, dug out a filter and filled the basket with coffee, poured water into the coffee maker, and waited 10 minutes for the pot to brew.
Answer: There is both an internal and external tank.  The internal tank gets filled by the external tank, and the external tank gets filled by pouring water into it.  There may be an option for a water line, but I don't have one hooked up.  All in all, I would say the keurig holds about 8 or so coffee cups worth of water at a time.