Daniel Island is surrounded by water on almost every side, and while the newer construction sits higher than much of the Lowcountry, heavy rain and storm surge still need somewhere to go.
Graded ground and drainage
The island was developed with proper stormwater drainage, which is why it copes better than older low-lying areas. Where problems do occur it is usually localised — a garage that sits level with the drive, a low corner of a garden that pools, or a crawl space under an older section of the island.
Storm surge is the real risk
Being ringed by the Wando and Cooper, the concern here is a serious storm rather than an ordinary downpour. That is a different planning question from routine drainage, and worth thinking about before hurricane season rather than during it.
A pump with no backup is not much use
Heavy weather brings power cuts with it. If you have a pump protecting anything that matters, a battery backup is what makes it work when it is actually needed.
Two minutes to test yours
Pour a bucket of water into the pit and check the pump starts, clears it and stops cleanly. If it hums without pumping or runs constantly, it needs attention now.