The economics of those OAS filters don't motivate me much, since two adults taking 15 minute showers a day each would result in $40/month for filters alone. 15

The economics of those OAS filters don't motivate me much, since two adults taking 15 minute showers a day each would result in $40/month for filters alone. 15 minute showers per day per person in a normal shower would cost me less than $15/month in water bills. Obviously there are use cases that need that more than I do, since I live in a wet, temperate area with plentiful water tables, but I think it demonstrates that our problems with water, and pollution, and other environmental issues have come from taking the cheapest/easiest options, so we need to work hard to make more attractive sustainable solutions for the average person.