I've noticed that whenever I come in contact with running water (especially when I do my dishes), I have a desire to urinate. A quick Google search (link,link) gave me few different hypotheses:

  1. Cold diuresis. Being in contact with cold water reduces temperature on the skin, which then constricts blood vessel to reduce heat loss, thereby increasing blood pressure and prompting the bladder to release excessive fluid.

  2. Afferent innervation. I wasn't able to comprehend all the details of the process, but it seemed like this hypothesis is pertaining to the nervous system than circulatory system, hence different from first hypothesis.

  3. Learnt psychological response. Second article linked above argues that this is a conditioned reaction, where even the sound of tap water triggers the desire to urinate. While it did not mentioned specific details of how this happens, I'm also assuming that this hypothesis is different from aforementioned hypotheses, because this hypothesis sounds more like a psychological response than biological reaction.

Which one of these hypotheses accounts for the desire to urinate when in contact with water? How exactly does it happen? If there is any other reason, feel free to add in the answer.

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    $\begingroup$ All three are probably contributors to some degree, although the third is a learnt psychological one and not physioly as you said. $\endgroup$ Jul 14, 2017 at 14:49
  • $\begingroup$ @comprehensible I find it a little hard to believe in the first hypothesis. It's bewildering to me that such a limited time of exposure to cold water in a small surface area (hands) will result in such a drastic change in blood pressure that will prompt bladder to release excessive fluid. Is there any studies done for this? $\endgroup$
    – Hosea
    Jul 14, 2017 at 15:37
  • $\begingroup$ @comprehensible I'll also be interested to see why the people will learn to have desire to urinate at the sound of tap water. Is there any reason that for that? $\endgroup$
    – Hosea
    Jul 14, 2017 at 15:39
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    $\begingroup$ The blood pressure is a direct response to your body being supported by gravity, or when it is weightless in water and in fact your upper body pulls upwards. It would be interesting to see when the pee reaction arrives, because, it's normally strongest above the groin up to the solar plexus, the visceral nervous response. There are some more answers here. quora.com/Why-does-swimming-make-you-need-to-pee $\endgroup$ Jul 14, 2017 at 15:45
  • $\begingroup$ Your point, and the article that I've linked to, seems to point to the case when the body is submerged in water. I guess this does not fully answer my case of washing hand, but your point certainly is true to body in swimming pool. $\endgroup$
    – Hosea
    Jul 14, 2017 at 16:10

2 Answers 2



I am writing this answer with an analogy.I have analogised your question to a childhood habit developed by our mothers-when she would want us to urinate all she had to do was to take us to the toilet and make a "siiii" "siii" sound to mimic the sound of running water(more or less)

Since I have analogised in that way I think the third hypothesis (referred in your question)is more apt.


What fascinated me more about your question was your comment-"I'll also be interested to see why the people will learn to have desire to urinate at the sound of tap water. Is there any reason that for that? – Hosea Jul 14 "

Indeed there is because we still have our mirror neurons [SOURCE]

What I wanted to understand is if mirror neurons contributed to Pavlovian reflexes.The answer was yes

Furthur I could find out from sources that the micturition process has centres in the brain stem which are controlled by higher centres in the brain.One of them was the "medial frontal cortex".

Read the following article:

The Pontine micturition center (PMC, also known as Barrington's nucleus) is a collection of neuronal cell bodies located in the rostral pons in the brainstem involved in the supraspinal regulation of micturition. When activated, the PMC relaxes the urethral sphincter allowing for micturition to occur. The PMC coordinates with other brain centers, including the medialfrontal cortex, insular cortex,hypothalamus and periaqueductal gray(PAG). The PAG acts as a relay station for ascending bladder information from the spinal cord and incoming signals from higher brain areas.[source]

From the outline in the following lines I could conclude that there are mirror neurons in this region which 'may' be involved in the micturition control:

Yoshida et al. [26] recently recorded from neurons in the medial frontal cortex, some of which selectively responded to self or observed actions within a social context [source]

Although research has confirmed that mirror neurons contribute to Pavlovian reflexes no such pathway has yet been discovered which can directly help us to confirm and understand its relation to urination urge in contact with water.


I asked my doctor about this issue. I had noticed the effect after age 65 and I remember my mother putting my younger siblings when they were just a year or two old, on her insteps as she sat down, and imitated the sound of running water - like a half whistle - soothing sound. And pee came. Now when I do dishes, I immediately feel to pee although I did not really want to before. I know this happens to most older folks. My doctor said maybe it is nerve anticipation that activates the urethral muscles, and too, maybe the instinct of a baby in the womb of the mother surfaces again. I did not quite get that part. I think it is a psychological thing where we respond to brain-nerve-urethra instinctive coupling, something we have no control over. I have started to empty my bladder before going to do dishes. When you shower, it is natural to pee when the water hits you, even if you had no urge to pee before. This is no fancy explanation but I just thought it might contribute.


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