Not unlikely. The stories are set from 1880 to 1900 or so, and indoor plumbing was first documented in the 1840's and remained a considerable luxury for some t

Not unlikely. The stories are set from 1880 to 1900 or so, and indoor plumbing was first documented in the 1840's and remained a considerable luxury for some time. In a building of the age of 221b Baker Street it's unlikely that it was overhauled to allow the necessary plumbing for indoor toilets.