Connecting 3.3 V of Arduino to analog input

Hi i want to connect 3.3 volt of Arduino board to analog input for controlling some water level .

is it safe for the board ? or Do i need to use a series resistor?

thanks for the helps

Which Arduino? If its a 5V Arduino then 3.3V is between 0V and 5V so its fine.

It never hurts to add a series resistor of upto 10k to an analog input.

3.3v is safe to use...but board type is important to know here. The default voltage reference for analogRead will also depend on your board voltage. Reading a 0-3.3v analog sensor with a 5v reference will only use 2/3 of your range. This is easy to fix. Just need to know more about what you're trying to do.

Am using an arduino uno

You should explain what your hardware is - we need to complete picture, not edited highlights, in order to figure out whether you have a workable approach.