Why do people think that shower/cleaning/toilet water is wasted? Greywater goes, nearly wholely passively, to settling ponds and from there to be cleaned and is put right back into the water cycle. It's like saying that a deer drinking in the woods is contributing to water loss. The only water that is removed from the cycle is that which is lost from the atmosphere due to solar activity. Unless Europe starts getting less rain (ha!), it's never gonna run out of fresh water!