Saving water is a small step towards better future. Water Lock is an automatic water meter and a locking device for use on bathtub taps. You just need to set the desired volume of water for the bath and let the bathtub fill up without monitoring. You generally know how much water you would like to fill in for your bath, so after the set amount has been filled, the flow will be automatically stopped when the water reaches the amount that you’ve set. So you end up avoiding over spill  wastage and have the freedom to do other stuff while you run up your bath water. It uses the principle of a combination padlock for its operation and doesn’t require electricity.