Venue-
On flat land, water rocket will blastoff to the air perpendicularly.

In contrast, on scraggy land, water rocket will blastoff to the air towards different direction.

Wind direction-
Strong wind may also affect the stability and the direction of the water rocket.

Bottle-
If the bottle is hard and large, the water rocket will not perform well.

The bottle like Bonaqua has the best result.

Speed of pumping-
If we pump too fast, the air may not go into the bottle.

So, we have to pump too many times to blastoff the water rocket to the air.

Ratio of the volume of the water to that of the air-
The ratio 1:2, 1:3 have a better result than the ratio 1:1 generally.