when i flush my system to much water is going back into system

b clarke, August 2008

when the toilet is flushed (occassionally) the water re enters and will rise above the handle and will leak through

Tracey, December 2008

I assume you mean cistern, not system? If so your ballcock will need adjusting so that the water input is cutoff when the ball is lower. Usually a simple nut and locknut. Slacken the locknut, turn the adjusting nut to the required position, then retighten the locknut. Use a spanner but do not use too much force, they can break easily.

Chicks Fan, August 2008