Why is it difficult for a fireman to hold a hose which ejects large amount of water at a high velocity ?

Explain using Newton's third law:

1. Newton's third law of motion states that every action has an equal and opposite reaction.
2. Hosepipes eject a large amount of water at a high velocity.
3. There's a backward reaction force due to the water rushing out.
4. This tends to decrease the stability of the fireman, thus making it difficult for him to hold it.