Why do many of us have the tendency to want, or need, to pee when we hear running water? Is this equal between female and male, and does age affect the phenomenon? David Cockayne, Cheshire Send new questions to nq@theguardian.com. Readers reply I believe it is a throwback (but a useful one) that we share with some (or all) mammals, that when we hear certain types of running water sounds most closely resembling a babbling brook, it indicates not only the availability of water, but fresher, cleaner water. So our body wants us to shed retained water (with all its filtered waste products) in favour of a clean fill-up. Liz Cullington, North Carolina Because when we potty train, and as a child, we hear splashing and running water as it hits the bowl or pot. The sound and the action become linked, so that now, a urination urge can be triggered by the watery sounds alone. There is no biological advantage to urinating in or near running water, and it would contaminate a fresh water supply, so the sound-action link in your earliest memories is the most likely explanation. foxinwinter I had a hernia op at about 5pm. I wasn’t allowed home until I’d passed water. Despite lots of running water sounds, I had no wish to, and eventually (after midnight) I was siphoned off. The doc said it was probably a prostate problem. JohnWig It never used to be a problem with me until recently. Nowadays I take a pee, wash my hands and then need to pee again. takalu Those who left the campfire alone to pee didn’t survive long. Those who went in a group did, but this only functioned when they all managed to pee. Evolutionary psychology is easy! Procrast I have never felt the need to pee when hearing running water, not in my childhood nor in my adulthood. Hearing running water when you want to urinate probably reminds you to do it, but for most it does nothing if you don’t need to. Gelion Urinating in flowing water guarantees that the waste is transported away from where you’re currently camped. As long as you’re taking water from upstream of where you perform your ablutions, you’re ensuring a clean supply of uncontaminated water. Tintenfische We are conditioned. Pavlov reflex. It’s automatic. Every time we urinate we hear a liquid running, therefore every time we hear running water we feel like peeing. tennysonsarah89 I suspect it’s innate. One explanation might be that excreting into running (ie a fast moving river) rather than in or near still water (ie a small lake or a sluggish river) flushes it out of the immediate environment resulting in better hygiene and a lower incidence of problematic things such as, say, cholera. Getting the urge in the presence of running water is therefore a trait that will be selected for. Something similarly instinctive exists in cats – they innately get the urge to excrete on dry, loose material a distance from their source of water and food so they can bury it (which makes them possible to litter train). They also have a natural aversion to their source of water, food and litter being proximate to each other, because of cross contamination; natural selection has eliminated the lazy cat who couldn’t be bothered to drag their kill a few yards away from their watering hole. On a definite related learned and entirely useless response note, though: every single time I go up the ladder to my office in the loft, I immediately have to come back downstairs again to pee. HaveYouFedTheFish It’s one of those psychology questions that seems immediately obvious but isn’t. Those that don’t pee into water in cultures other than ours also experience this, so it’s likely to be a combination of things – classical conditioning of a behaviour that is like a reflex, plus something else. I would suggest that the sound of running water is in some way relaxing. It’s something of an acoustic pillow maybe? If this is the case then the activity in the parasympathetic nervous system will be activated, the sympathetic will be reduced, so sort of an external cue that “it’s OK, you don’t need to run away right now … relax” is the message we are given, resulting in it being OK to pee (combined with a lump of classical conditioning). psychtalk I recall doing some consultancy work for a care home client. They had built a smart new residential home for elderly people, complete with an elegant fountain in the central courtyard. Looked very impressive during commissioning and the opening. But they had to switch the fountain off a week after the residents moved in, for just this reason. Now I am retired I can relate to that challenge. MartinPWilson When I was a young chef, not the jaded husk of a man I am now, we used to have a massive stockpot, it was huge – 20kg of bones and about a 100 litres of water. This pot sat on a vast burner and had a cold water tap on the wall above it. Attached to the cold water tap was a short length of hose, and this was used to fill the pot, and top up when needed. After many flooding incidents when this tap was left unattended we decided to make the hose shorter, so you had to physically hold it up to the top of the pan, meaning that you couldn’t leave it to overflow. Any man that can stand holding a length of hose and pouring 100 litres of water into a pot without needing a wee is either dead from the navel down, or deaf. BillumBleigh On a similar note – every time I hear Rees-Mogg’s voice I want to vomit. DomiRacerX Does the sound of a landslide help with constipation? MickJames1234 If it’s coming your way, the chances are pretty good. Pummeluffpapa