Outputs must be off after a restart

[Preetz]

After a restart, for example after a power failure, all my outputs (GPIOs) are set to their last known state.
I'd rather like them to stay turned off consequently.
What is the best way to do so?

[Preetz]

Additional background:

Im building up a controllsystem for a friends's terrarium.
One of its devices is a sprinkler, which must not spray for too long. This is a question of live and death for the terariums residents.
In case of a failure while the sprinkler is on, after restart the sprinkler stays on whithout turning of automaticly.