Absolutely not. The High Tide does not damage electricity, power and pumps: the water from shower and sinks remain clean and potable. This happens thanks to the complex Venetian hydraulic system that avoids that the lagoon water enters in the pump during the high tide.
HOW CAN I UNDERSTAND THE LEVEL OF THE HIGH TIDE?
The best device to know the level of the tide is the mobile app HI!TIDE: it provides the forecasts of the tide in the next 3 days, so you can organize your day based on reliable data. Otherwise you can consult the official website of Venice Municipality.
To make it easier I will explain, with some pics, the meaning of the numbers. So, If you want to go out, you can understand how much water you have to face!
Take a look to the chart on the right (provided by “Comune di Venezia” website).
You can consider the high tide as annoying thing from the 110 cm. Behind this number there is high tide only in some points of Piazza San Marco, but you can visit the square without problems.
The table (provided by “Comune di Venezia“) can show clearly the highness of the tide.
THE VENICE HIGH TIDE ALARM:
Over the 110 you will hear the famous and loud alarm in all Venice: it warns that the tide will start to grow within one hour. Inside the alarm you will hear a bell: every bell stands for 10 cm over the 110 cm.
Example: Two bell inside during the alarm means: 110cm + 10 + 10 = 130 cm total.