Answer:
If you mean the lowest class of peasants (the serfs), then the answer is none.
Most people would have lived in a medieval "long-house", with only one long room divided into two sections - one half for the family, around a central hearth on the floor and a hole in the roof for smoke to escape, and the other half for animals such as cattle, pigs or goats. At the rear of the house would be a small garden area with a pit into which all the human and animal waste would be deposited. This cesspit was emptied from time to time by a man known as a "gongfermer" (literally "cesspit farmer") who took the waste away for later use as manure on fields.
More wealthy peasants, including craftsmen, merchants and others, lived in better houses that might include a privy - simply a small room with a toilet seat projecting out from a wall so the waste would fall straight into a cesspit outside.