Instruction: Extract information from the supporting document to answer the given question.

Input:
Question: What size filter do i use?
Document: If you use only tap water this could be a bigger deal though. Keep in mind though that the coffee makers that do have filters have fairly small, expensive filters that will need to be replaced. An external filter is probably cheaper in the long run, and you can use if for more than just coffee. The filter is also a source of failure as well.
This is the 3rd Black and Decker coffee maker we've had, with the other two each lasting several years and were happy with those. This model, however is a big fail. It does not accomodate a permanent gold foil type filter so have to use paper filters. The cup level markings on the carafe are only on the right side so as a left handed person it is difficult to fill without twisting my wrist awkwardly.
pot I've tried. There is no water filter but really if you're going to leave your coffee on a hot plate burner like this then filtered water isn't going to change much. If you live in areas with high sulfur then use bottled water, but then you already knew that. The coffee that is produced by this machine is perfectly acceptable for early morning zombie mode or when you've got a lot going on in the house.
No adjustments for brew strength, pot warmer temperature, or option for 4 cups or less, or turn off time. None of these seem a big problem, on coffee makers that had these features I left them at the nominal setting anyway. The small pot brew option I did use a few times, but I also expect that it will brew a small pot just fine without that option.4. No water filter.
Makes great coffee with one filter but I prefer to use two paper filters together to prevent any coffee grinds from seeping into the carafe. Plus it seems to taste better with two filters. The sneak a cup feature works better than our old expensive unit but you have to be sure to slide the carafe out without lifting upwards. I'm guessing the one star reviews have to do with this coffeemaker being made in China by the millions.
bought this coffeemaker about 3 years ago. and have loved it since day one. easy to program and easy to clean up. the water reservoir has a nice angle to it, so you can fit a baby bottle brush to inside to clean it out from time to time. nice auto off feature that automatically shuts off the coffee maker after 2 hours of keeping your coffee hot. minimum noise, and good tasting coffee. i suggest you use a permanent filter with this coffee maker.
this is the best coffee maker ever. love this product. makes great coffee and it is the perfect size for company
I've only had this coffee mnaker for a total of 24 hrs. This is our very first coffee maker and I really like it so far, did the water only run and the "new" plastic smell is gone. Coffee tastes great, programmable delayed brewing works fine and easy to set up if you read the manual. Very, VERY quiet and size is perfect for our small apartment.
This coffee pot is a good size one and really nice looking. The timer is just awesome. No more waiting for coffee to brew. If your up early you can simply turn on, and the pot has the ability to allow you to grab a cup before it is totally finished brewing if ya need one in a hurry! Love how the coffee tastes also. The temp the coffee  is brewed at makes a HUGE difference in flavor. I couldn't be happier with my purchase.
It's an excellent product and does exactly what it says, it makes coffee automatically and/or manually. It has a timer which is preset but needs to be turned on every time, which also means you don't forget to put in the coffee/water. The actual coffee pot is good size and easily serve 12 medium cups of coffee. You do need to put a little more water for the end amount of coffee in the pot. Good value for money.
Answer: A 10-12 cup basket filter. An 8-10 cup basket filter also works, if you aren't planning on having a full pot of very strong coffee.