Short answer, it depends. There are measures to mitigate the flooding, such as improving ground/soil drainage, installing soakaways, ensuring drains are kept clear & having sump pumps installed. However, if the flooding is quite serious, & the area surrounding your property is also flooding - or passing cars are causing tidal effects, only a form of Bung Wall and pump system will enable you to stop your garden from flooding. This can be quite expensive, & funds may be best spent letting the garden flood, but defend your property instead.