It seems there is precedent to allow for netilas yadayim when you don't have a cup, by turning the sink on and off for each rivi'is per hand. By employing this method you satisfy the requirement of koach gavra.

What about a situation where the sinks are all automatic? Would waving your hand to turn on the sink still be considered koach gavra?


2 Answers 2


The Avnei Yashfei 30:5 writes that using a faucet does not count as using a kli since it is connected(to pipes) to the the house and has a din of being attached and cannot be considered a kli(utensil). So even turning the faucet on and off with your hands wouldn't help. Rav Eliyashiv holds this way as well and is also quoted in Ashrei Ha'Ish(Chelek 1:pg.203 the footnote uses this Avnei Yashfei as the source).

Avnei Yashfei Text:

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  • 4
    Regarding R' Elyashiv, there appears to be a contrary claim in this answer: This is subject to a dispute among modern day poskim if the faucet has a din of a kli. Rav Elyashiv and Rav Ovadia Yosef both held it did have a din of a kli; thus, if no cup is available, one can turn the faucet on and off twice (or three if Sephardic) on each hand, since turning on the faucet is considered "koach gavra".
    – Fred
    Jan 13, 2016 at 5:04
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    That claim has no source for Rav Eliyashiv,,my answer provides 2
    – sam
    Jan 13, 2016 at 5:07
  • 1
    Yes Gaon Echad is always Rav Eliyashiv in Avnei Yashfei per his hakdama
    – sam
    Jan 13, 2016 at 5:16
  • 1
    I added the Ashrei Haish source,just looked it up.
    – sam
    Jan 13, 2016 at 5:19
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    @Shoel u'meishiv what are you referring to?
    – sam
    Aug 22, 2018 at 19:11

Regarding human/animal power

Similar to @Loewian by a regular valve the human is actually relieving the pressure that is in the pipe (so the first water that comes out is regarded as human propelled ( source))
But by an electrical valve the human is not reliving the pressure physically but it is only being caused by him

(There might be an opinion that if a robot washed your hands it is OK, then it will be OK in our case (b"n I will look for it))

I might be wrong since the human is the one activating the valve, (by the monkey the monkey is pouring not because of the human but by himself)

Edit I think I am wrong

There is a biblical requirement to shecht an animal to eat it, there it is clear that you need the shochet's propulsion,
but if the shochet propelled something (a stone) and that thing (the stone) propelled the knife is not written clearly if it is sufficient
but to the simla chadosho 3.2 decided that it is not sufficient since it might not be considered the shochet's power

In our case the washing of the hands is a Rabbinic decree so it is very possible that the koach kocho is considered his koach (that propelling something by propelling another thing is considered his propelling)

So causing the valve to open by triggering the electric motion sensor which then triggers the electric valve might still be considered human propelled (I do not see a reason by extra steps in process sill be different then just 2 (ie hitting the valve by throwing a rock on it)

Would waving your hand to turn on the sink still be considered koach gavra?
it might so if no choice you should do it, but still cover your hands

  • 1
    The Mishna says even a monkey can pour the water.
    – Double AA
    Jan 6, 2016 at 18:25
  • @DoubleAA i think That is the source regarding the robot, but from what I understand a monkey is more then a electric valve (it is alive)
    – hazoriz
    Jan 6, 2016 at 18:32
  • So this is one long comment...? Jan 13, 2016 at 8:54
  • @DannySchoemann yep
    – hazoriz
    Jan 13, 2016 at 12:35
  • The Be'er Heitiv YD 19:30 writes that a monkey by shecita is not good but washing in OC is different since it's a d'Rabbanan
    – sam
    Jan 19, 2016 at 16:42

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