Sandom Branch is a long tributary to Blackbird Creek in New Castle County, Delaware. Sandom Branch is one of the major tributaries to Blackbird Creek above tidal influence.
Sandom Branch rises on the Duck Creek divide about 2 miles south of Blackbird, Delaware.
Sandom Branch drains of area, receives about 43.8 in/year of precipitation, has a topographic wetness index of 556.57 and is about 22.6% forested.