Reference for Zevachim 41:5

לא מי מערה איצטריכא ליה שלא תאמר כל גופו טובל בהן ידיו ורגליו לא כל שכן

Hence [if he used] the water of the laver in a similar way to the water of a pit<span class="x" onmousemove="('comment',' I.e., putting his hands and feet in the laver.');">⁶</span> and officiated, his service is valid? - No: it is particularly necessary for him [the Tanna] to teach about the water of a pit.

Jastrow