## 4 Discussion
The final consideration around performance is related to the full-scale AC systems and how well they are represented by the PF200. Several water treatment plants designed by the AC group are currently operating in Honduras and Nicaragua. Water quality produced by one of them--a 16 L/s water treatment plant in Moroceli (Honduras)--was monitored for one year between 2016 and 2017 and is provided in the Supplemental Materials S2. Figure 7 and Table 2 compare the PF200 performance presented in this paper with the far superior performance data provided for Moroceli. A significant discrepancy between the water quality delivered by both units should raise questions about both the degree to which PF200 represents the full-scale AC plant and indicates the need for a technology performance assessment conducted in a controlled environment. Figure 6: Performance of both systems vs. water quality standards from different countries. Figure 7: PF200 vs. Moroceli; comparison with a 16 L/s AC plant in Moroceli (Honduras) reveals that the reported performance of the full-scale plant is much better than the registered performance of the pilot system. The quality of raw water plays a foundational role in determining the efficiency and reliability of drinking water treatment systems. Variability in raw water--caused by seasonal changes, pollution, or climate events--can significantly affect operational processes such as coagulation, filtration, and disinfection. High levels of turbidity, organic matter, or microbial contaminants in untreated water may increase chemical dosing requirements, reduce filtration efficiency, and compromise disinfection, potentially leading to health risks and regulatory non-compliance. Studies have shown that raw water quality parameters such as turbidity and UV254 absorbance are strong predictors of the final treated water quality, particularly in small systems with limited infrastructure [54]. Advanced control systems that monitor real-time raw water quality can help adjust chemical dosing and stabilize output water quality, as demonstrated by successful implementations in China and elsewhere [55]. Furthermore, large-scale risk assessments have shown that addressing raw water quality at the catchment level--by identifying key land use and climate pressures--enhances the resilience and sustainability of water supply systems over time [56]. As such, comprehensive monitoring and management of raw water quality are essential for both short-term treatment efficiency and long-term water security. This leads to questions about the viability of performance assessment in an environment where a wide range of external factors affect the tested installation, which also corresponds to the double inflection of the raw water turbidity curve on the frequency distribution plot, with an additional inflection point around the 70% rank. This, combined with a high value of standard deviation, implies a significant influence of an unknown external factor over the data. Various possible factors could have contributed to that behavior, such as changes in the watershed, weather conditions, human error, or malfunction of the analytical equipment. Independent of the nature of the disturbances influencing the results, it confirms the need for performance tests conducted in a controlled environment. The need for further performance assessment in a controlled environment is fortified by a paper from 2018, which analyzes the operation of six gravity-fed water treatment systems built in rural Honduras, including the Moroceli plant, according to AC design recommendations [42]. The authors focused on two metrics characterizing the water quality--turbidity and the _E. coli_ counts--and measured them at different stages of the treatment process. Performance evaluations show consistent removal of turbidity to levels