dead as ditch-water

dead as ditch-water (not comparable)

1. (simile) Unquestionably dead.
   • 1886 October – 1887 January, H[enry] Rider Haggard, She: A History of Adventure, London: Longmans, Green, and Co., published 1887, →OCLC:

     "Do you go in if you like." But I merely shook my head, my excitement was as dead as ditch-water, and my distaste for the prolongation of my mortal span had come back upon me more strongly than ever.

• dead as a doornail
• dead as a dodo
• dull as ditchwater