City Installing Sewer Line Today

To compare apples to apples according to article below, Mexicos MCL is 25 micrograms/l.
Which equals 2.5 mg/l. 2.5 times our MAC level in Ontario.
Arsenic is extensively used in mining applications and ends up in settling ponds.
Mexico has been known for bad water for decades. I am making assumptions here, but its also known for its corruption. I would bet pesos to tacos there is a correlation.
Standards for arsenic in drinking water: Implications for policy in Mexico - PubMed