No, 10 years, but only for regular weekend exercises (5 times a year or so) plus being on call for emergencies. Whereas military service or other civil service (typically helping in some hospital or care facility) was a 8 to 24 month block of duty, just like any other care worker or soldier.

THW was seen as the really easy way out of the draft (if you could get a spot), because emergencies were rare and weekend exercises were "easy". Informally THW stood for "Trinken, Helfen, Weitertrinken", "Drinking, Helping, Continued Drinking".