In homes considerable amount of water lost every day due to refilling of water tank. We can avoid this just by having little knowledge with electronics. Here [[wysiwyg_imageupload::]]I have described a simple circuit with the help of two IC that is LM741 and UM66 which will give an musical alarm when your tank become full so that you can avoid wastage of water due to over flow.In this circuit IC LM 741 is an operational amplifier which is working as a comparator to sense the level of water present. And IC UM66 is used as melody generator. When tank is empty, water will not touch metal plate or sensor in that case inverting pin of LM741 IC is at higher potential in comparison to non inverting pin of IC1. Keep on reading to know more.