Digging a trench allong the back of the garage ,to a nearby manhole .Getting a roll of land drain pipe from a merchants and some pea gravel. Trench about 350mm deep 2500 wide ,layer of gravel 50mm-70mm lay in the plastic drain ,lead it to the manhole with a slight fallk,nock a hole through.Then fill grevel on top and around the pipe ,and back fill the soil.
The water will go inti the ground and will naturaly follow the porous gravel and pipe th the manhole .


Job done