As stated in the article, this isn’t a big problem for communities with centralized water treatment systems, rather for individual homes drinking well water which is contaminated by agriculture.

In a municipal treatment plant you have a few options for removing nitrates including reverse osmosis (membrane filters with very small pores, allowing them to reject very small molecules), ion exchange (swap nitrate with another, less harmful ion), or biological treatment (use microorganisms to turn nitrate into nitrogen gas).

In your home, reverse osmosis is really the only feasible option, which can be expensive to install and costly to maintain. Ideally, some sort of tax on fertilizer would be used to pay for these in house treatments, but that would increase the cost of food.

I’m a water engineer with a PhD, so not a tech nerd but definitely a nerd :) I came here mostly because I find the Reddit app annoying and the app I was using came here.

The Romans used lead as a sweetener…

I don’t know the details about alum production (assuming that is what you are referring to), but there are many alternative coagulants available now. Sure the supply logistics would be incredibly challenging and many people would have to boil their water or use point-of-use filters, but this take is pretty doomer in my opinion. Most plants use alum because it’s cheap and easy, not because it’s their only option.

Water is disinfected with either chlorine, chloramine (ammonia + chlorine), ozone, or UV light. In North America chlorine is almost universal because it provides disinfection residual, which keeps water safe while it is travelling from the treatment plant to the consumer. Fluoride is added solely as a supplement to improve dental health.