If it is less concentrated surly the family will use more at a time. The more concentrated it is the less they will use. In my opinion you are not saving, you are lowering the strength of the anti-bacterial by adding plain water to it. ... View related article.
This idea would not be suitable for my windows. Too much direct sun light, surly would not be good for glass etc. and the shelf will only distract your view - may also look a bit messy from outside (sorry!). ... View related article.
