The worldwide water emergency requires immediate solutions because pollution and water shortages have reached critical levels. The current water treatment methods fail to eliminate multiple contaminants including heavy metals and organic substances and nutrients and pathogens while producing additional waste products and requiring significant energy consumption. The chapter investigates 3D-engineered polysaccharide sponge formulations as an advanced water and wastewater treatment system for the future. The combination of natural abundance and biodegradability and multiple functional groups (–OH, –NH2, –COOH) in biopolymers such as chitosan and cellulose and alginate and carrageenan enables sponge structure enhancement through freeze-drying and 3D printing and electrospinning methods. The 3D engineering process transforms traditional polysaccharide materials by creating porous structures that enhance mass transfer rates and adsorption capacity and mechanical strength. The performance of these sponges receives additional enhancement through the addition of functional additives which include nanoparticles (Fe3O4, TiO2, AgNPs) and carbon nanomaterials that deliver catalytic and antimicrobial and magnetic capabilities for specific pollutant elimination and self-cleaning and recovery operations. The multifunctional sponges show excellent performance in heavy metal removal through adsorption and ion exchange processes and organic pollutant degradation through photocatalysis and nutrient capture through biofilm support and pathogen elimination through filtration and disinfection. The research examines how these materials can be integrated into current treatment systems through pilot-scale implementations and identifies future development paths for smart responsive sponges and affordable production methods. The 3D-engineered polysaccharide sponge system offers a scalable eco-friendly solution which demonstrates high effectiveness for securing worldwide water resources despite facing regulatory hurdles and stability concerns.