Iron is the most common element on Earth, by mass, and is present in the human body in significant amounts, mostly in our hemoglobin. It was one of the first metals to be mined and smelted by humans, after copper and lead. It has been mined in Maine since the 1800s, most famously at Katahdin Iron Works. Iron is widely dispersed in Maine soils and groundwaters (and therefore in well water), and can also be present in drinking water due to cast iron main corrosion.
While iron is critical to human health, its presence in drinking water is typically unwelcome, as it adds a bloody taste and rusty color.
...See also "What is Iron Bacteria/Red Slime?"
Maine Maximum Exposure Guideline for Drinking Water limit: 5.0 mg/L
USA Primary Drinking Water Standard limit: n/a
USA Secondary Drinking Water Standard limit: 0.3 mg/L (nuisance level -rusty color; sediment; metallic taste; reddish or orange staining)
LOCAL: Maine.gov, "Iron and Manganese [in drinking water]" (webpage)
NATIONAL: USA Centers for Disease Control: "Iron" (Nutrition)
Maine Geological Survey / Michael Foley, "The Iron Age of Maine: 1800s - Katahdin Iron Works" (16 pg .pdf) and Thomas Weddle, "The Iron Age in Maine, Part II: The Shapleigh Iron Company: A Foray into Industrial (geo)Archaeology" (19 pg .pdf)
MinDat.org, "Iron" (non-profit mining information website)
MEL Test Methods for Iron
Drinking Water – EPA 200.5 (SDWA Compliant)
Wastewater – EPA 200.7 R4.4 (NPDES Compliant)
Solids – EPA 6010B, 6010C (SW846) (RCRA Compliant)
Container: plastic, glass
Hold Time: 6 months if preserved with HNO3 to pH<2, otherwise 2 weeks
Preservation: HNO3 to pH<2
Container: plastic, glass, baggie
Volume: a least 150g
Hold Time: 6 months