Flooding/Drainage

Hi, I'm looking for some advice regarding flooding.
During heavy rain storms or even normal rain that goes on for hours our utility room floods. The drain blocks up as though it cant cope with the rain, my husband has put his hand down the drain & hasn't found any obvious blockages. We cant get our drain rods down there as we cant get it around the u-bend, maybe its worth investing in the attachment?? Incase there is a blockage further down.
It probably doesn't help that the back door isn't raised off the ground, so there only has to be the slightest bit of water & it comes flooding in.
Is this likely to be caused by a blockage?
We have been living with this for 5 years now & I'm sick to death of it!!