From the 7^th of December, 2007 Venice city now has a high tide alarm bell that distinguishes four different high tide levels.  It is a more sophisticated alarm than the old single siren system.

A siren alerts the listener to an impending high tide.  The four different tones allow the listener to understand at what height the tide is expected to be:
110cm:  a long ring on one continuous note
120cm:  two rings on an ascending note
130cm:  three rings on an ascending note
140cm:  four rings on an ascending note

The alarm, which will be repeated more than once at a time has been studied to be as simple as possible to understand and also loud enough for the elderly to hear.
This new digital alarm system was installed recently to replace the old electric sirens.  It insures full acoustic coverage in all the city and will be put to use in other areas as well. 
The alarms have been installed on council or state land inside bell towers themselves so as not to aesthetically displeasing.

Do you wish to be alerted to a high tide?
Sign in on line with the high tide service, Centro Maree

Do you wish to see the outlay of the duckboards set up in Venice during high tides?
Check the maps for the 2008-09 season

For further information please consult the meteorological and high tides web site  

Useful information:

Istituzione Centro Previsioni e Segnalazioni Maree
Palazzo Cavalli
S. Marco, 4090
30124 VENEZIA 

Previsions
tel 041 2411996 (recorded message, 120 lines available)

Infomation
tel 041 2748787
fax 041 5210378
e-mail    maree@comune.venezia.it
website  www.comune.venezia.it/maree