Green method of stemming the tide of invasive marine and freshwater organisms by natural filtrationSeawater used for ballast typically contains numerous macroscopic and microscopic organisms discharged into the oceans worldwide. Thus, ballast water disposal is believed to be a primary vector for globally spreading aquatic invasive species. Records of ballast water-mediated introductions and their threat to marine biodiversity, coastal economies, local cultures and livelihoods, and human health are well-documented by various studies. Subsurface intake systems as a source of filtered seawater or freshwater eliminate the macro-and microorganisms from ballast water at ports where it is uploaded. This natural filtration technology using wells or galleries has been demonstrated to be cost-effective in improving water quality (pretreatment) in seawater reverse osmosis desalination facilities.