Freshwater mussels are recognized as ecosystem engineers because they perform water filtration through filter feeding. This study aimed to quantify the changes that occurred in pond water after filtration by freshwater mussels Lamellidens marginalis. Specimens of L. marginalis were gathered from a small pond near Palghar in January. Mussels are hand-picked and stored in buckets of water. Twenty-five individuals of this species were used to assess the changes in various water parameters, including Biological oxygen demand (BOD), turbidity, hardness, and pH. Before the estimation, the mussels were acclimatized to laboratory conditions for approximately 7 days to ensure they adapted to the pond water parameters before filtration evaluation. The water parameters were examined before filtration while acclimatization was occurring. After the acclimatization period, the mussels were housed in a fish tank with about 4 liters of pond water for 2 days. The water parameters were then examined again, which revealed a difference. The BOD was nearly half of its initial value, dropping from 2.4mg/l to 1.2mg/l, and the turbidity fell by 8 NTU. However, the hardness of the water was 16mg/l lower than the starting value, and the pH was dropped from 7.46 to 7.16. This suggests that mussels play a significant part in freshwater filtration to preserve good water quality.