Wetlands are defined as areas of soil saturated with standing water. These areas are rich in biodiversity, containing numerous plants, animals and microorganisms. Wetlands act as natural filtering systems for runoff and can improve the water quality in an area. To demonstrate the importance of wetlands to a nonscience major introductory environmental science class, we designed a small freshwater wetland filter. This filter is able to reduce the amount of ammonia present in water entering the system. Sequencing the bacteria present in the soil of the filter identified bacteria capable of performing anaerobic ammonium oxidation (anammox). In this paper, we describe how to construct the filter and use it during class. It is our goal that this filter gives students a better appreciation of the role wetland ecosystems play in maintaining water quality.