Constructed wetlands (CWs) have gained strong attention as controlled, environmentally friendly, and economically efficient wastewater purification systems. Designed to operatively mimic natural wetlands, they aim to reduce contamination of receiving water bodies through biogeochemical processes. However, research on the long-term monitoring of field-scale CWs designed to purify domestic effluent is limited, making it difficult to determine best-management approaches. We studied the long-term performance of the Laratinga Wetland near Mount Barker (South Australia), which was constructed in 2001 to purify domestic effluent from the town. The wetland has received increased hydraulic and pollutant loadings over the last decade due to the increased population and expansion of the town. The treatment capacity of the wetland has been exceeded, with high ammonium (NH4+-N) concentrations of 40.6 mg/L (averaged over 2016 to 2020), and dissolved oxygen (DO) concentrations as low as 1.3 mg/L during the night now a common feature (Allen et al., 2022). High NH4-N concentrations likely resulted in unionised NH3-N being at a potentially toxic level, despite pH being circumneutral. A trial was performed using an aerator, aiming to alleviate the hypoxia and decrease NH4+-N via promoting nitrification. While DO was increased, NH4-N concentrations showed minimal change (Allen et al., 2023), highlighting the importance of meeting design capacity to ensure wetland treatment processes are not overloaded. A DET-DGT study of sediment nutrient concentrations also showed high NH4-N, low nitrate (NO3--N) and low redox potential, which is also symptomatic of high organic matters to the sediment and anoxic conditions being maintained.