So what is it? Phospate Removal Material doesn’t tell me much. Is it activated charcoal? Ground peanut shells? I need to know.

A paper on the topic reports that

Several adsorbents have been used for phosphate removal from water. They include; aluminium-modified biochar (Yin et al. 2018), aluminium-doped magnetic nanoparticles (Xu et al. 2017), laterite soils, and black cotton soil (Reddy et al. 2020).

Sounds like it’s time for a municipal broadband solution. If AT&T doesn’t want the business, fine. Let’s not force them to take our money.