Similarly, both UV systems had pronounced decline in cost and a moderate decline in GWP with an increase in adoption lifetime. This finding can be attributed to the higher capital cost requirements associated with these advanced systems. In the case of the UV mercury lamp system, a 1-year adoption period was associated with a net cost of 24.59 USD•cap -1 •yr -1 and a GWP of 7.28 kg CO2 eq•cap -1 •yr -1 (Figure ). However, the cost decreased significantly after approximately 5 years, with 15 years adoption period resulting in a net cost of 9.74% of the 1-year adoption cost (Figure ). On the other hand, the 15-year adoption period resulted in 61.81% of the 1-year adoption GWP (Figure ). This only moderate reduction can be attributed to the GWP from the mercury lamps that require replacement throughout the adoption period. The UV LED system had the highest cost of all the POU technologies over the entire range of adoption periods (Figure ). A 1-year adoption was associated with net cost of 64.92 USD•cap -1 •yr -1 , while a 15-year adoption yielded a net cost was 8.95% of the 1-year adoption cost (Figure ). The GWP for a 1-year adoption was 4.15 kg CO2 eq•cap -1 •yr -1 and 32.10% of the 1-year adoption GWP (Figure ). The moderate reduction in GWP with adoption period for the UV LED system can also be attributed to the required lamp replacement. Overall, the drastic reduction in costs versus moderate reduction in GWP with adoption period for the UVbased system present tradeoffs in their adoption. These results suggest that long-term adoption is the preferred approach when considering the costs of UV systems. percentiles are plotted with the dashed lines. Note that the household size was set to 4 people to focus on how adoption period can influence cost and environmental impacts.