I have been getting interested in Rope Water Sensors which can detect when any part of the rope is wet and then using an Arduino to process that and generate an alert. Good for server rooms or anywhere you do not want water.
These things are made (or sold) by a lot of companies but they all include the electronics.
From the picks of the rope it uses a system of 10 x 30cm zones for sensor detecting.
The sensor could be two wires wrapped in some water absorbing fibre (lady pads) that insulates the wires when dry and shorts when damp/wet.
Alerting the Arduino would then be 10 pins waiting for circuit connection and computes, water between foot 5 and 6 (could add an led that lights up on that area?)