Dipping into drawn water [Mayim Sheuvim]:[1]
Dipping one’s hands into drawn water, even if it is more than 40 Seah, does not purify the hands and hence a blessing may not be recited upon this washing. [Nevertheless, if a vessel is not available, one is to dip his hands in the water without a blessing.[2] If a vessel later becomes available one should wash his hands properly with a blessing.[3]]
[1] Seder Netilas Yadayim 8; Ketzos Hashulchan 4:2 “If a vessel is not available one should nevertheless wash his hands but without a blessing”. This must be referring to drawn water that is not within a vessel.
Ruling of Admur in Kama: In Kama 4:3 Admur rules: “If one does not have any vessel then he may nevertheless still rinse his hands with [even] drawn water [which is invalid for a Mikvah] and say the blessing, as the sages did not make any mention of a specific way of washing, and thus as long as he has washed his hands he may say the blessing”.
Other Poskim: The Michaber 4:7 rules that initially one is to be careful to follow all the laws that apply when washing for bread. Hence according to the Michaber one is initially to use a vessel. The Rama rules that Bedieved a vessel is not needed, and so rules Admur in Kama ibid. The following Poskim rule like Admur that one must use a vessel and otherwise the washing is invalid: Mor Uketzia [brought in Kaf Hachaim 4:27]; Zekan Ahron 2:1. Kaf Hachaim 4:40 concludes a blessing is not to be said due to Safek Brachos Lihakel.
[2] Ketzos Hashulchan 2:4: Seemingly this is done in order to be allowed to pray and learn Torah. Alternatively it is to suspect for those opinions which validate the washing.
[3] Ketzos Hashulchan 2:4 based on Admur in Siddur that the first washing was completely invalid.