I’m one of the many who’s a bit notorious for just letting too much water go down the drain.  It’s not that I mean to, it’s just when I’m half awake in the morning, I’m not that worried about water consumption.  If you’re not ready for a device that just shuts off the water when you’ve used too much, then this Waterpebble is a nice happy medium.  Instead it goes for a subtle approach. It has 3 different shades of lights, one is green, then there is red and yellow.  You can pretty much guess which colors mean what.  The red means you need to get your tail out of the shower, the yellow means you should speed things up a bit and the green means you’re in the clear.  It sits right next to your drain and just keeps track of how much water goes down it.  Right now this is a concept design by Paul Priestman

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Waterpebble tracks water used