Nitrates are a ubiquitous and universal pollutant in surface waters. They are associated with algal blooms and eutrophication of watercourses as well as direct toxicity to aquatic organisms. Many remediation techniques exist however they are often expensive and highly technical. Adsorption is an alternative that can be much easier and cheaper to implement. Here we used spent coffee grounds (SCG) as a low-cost biosorbent. The grounds were modified using non-toxic and biodegradable chemicals to specifically target biosorption of nitrates. Adsorption of nitrates was first tested in lab-made nitrate solutions. Modification, agitation, biosorbent quantity, pH, contact time and temperature were all examined. Optimum adsorption occurred at pH of 7.5, 200 rpm, and 18±2°C using 2 g of biosorbent in 50 mL at 25 mg NO3-/L. SCG did not adsorb any nitrates whereas modified grounds (MG) removed 83.2% of nitrates in 24 h. Because loose coffee grounds are impractical for field applications, containment systems were trialled. The most effective was a 90 µm-mesh pouch closed by a zip tie. In 1 h, MG in pouches removed 53.5% of nitrates from a lab-made solution and 58.6% from the spiked stream water. In 24 h, 90.1% and 90.5% of the nitrates were removed from their respective solutions. Ecotoxicity tests are currently underway to establish the toxicological impacts of the MG and any associated leaching. We aim to create a product that is safe for ecosystems, field applicable, economically advantageous and widely translatable.