They are now saying it was more like 2 months worth of rain in one night, and the drainage systems in the whole region just couldn't cope with it all. Our ground is clay and when we dig down only a foot or so we hit a solid seam of thick clay, so there is no way for water to easily soak away. Our houses were only built 6 years ago, so we are also going to be looking to see if the original builders actually put in adequate drainage for the development, and if not sue! We definitely don't want this happening again in the future. Although longer residents in the area say it hasn't ever happened like this before.