Each time someone uses a flush toilet as a urinal, a lot of sanitised meant-for-drinking-cooking water gets flushed down the sewage. That is a huge waste of precious and 20 years ago when learning about country's development, we were told that in the future, fresh water shortage is going to be one of the constraints obstructing further developments.
Recently I read about a waterless urinal in a building in my city, but had no time to check. Will do some Google searches later, but for the moment, I think this "almost waterless urinal" will do as it uses only a fraction of the water that get flushed down the sewage each time you flush a toilet. See photo below:
There is a better photo with a less discrete stream (droplets caught by flash when it should be showing an almost continuous stream)
Will update with a better one when I find it or I get a new one, but please don't try to look further down the photo.
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