U can make a flood alarm or u can make a JCB using ingestions.
1. Materials needed r ..a cartoon box..aluminium foil..alarm..battery of 9+volt ..pole..talac sheet..saltwater. .conjeting wires.
2.cover the box vit talac sheet .cover the pole vit aluminium foil.
3.make 2 small holes at both sides on the box.
4 stick the pole at b/w the box.take a piece of cardboard place it above the pole .
5place a battery nd alarm on the top of the cardboard.
6 take wire nd connect it to battry nd alarm . again connet the wire to other side of alarm nd take it out frm one hole nd bring it back inside the box frm 2nd hole do as the same other side.
7.then take saltwater nd put it inside the box. It should touch the wire which u hav brought inside the box.
the moment when the water reach till the wire the alarm will buzz.