Siphon-based Rain Meter
A rain meter without moving parts. It will be an add-on module for Elektor's USB Long-Term Weather Logger http://www.elektor.com/100888
What is the physical principle used for measuring water level ? I thought it could be a capacitive measurement (a capacitor made of two electrodes glued on each side of the vertical pipe, in which water level would change its value), but it seems that you used something else...