http://www.epa.gov/nrmrl/wswrd/cr/corr_res_iron.html

铁倒是好的多。 :-)

Effects of Iron on Human Health, Water Quality, and Distribution System Infrastructure
Iron is an essential mineral for human health in small concentrations (iron deficiency can lead to anemia). Unlike lead and copper, ingesting iron from drinking water is not directly associated with adverse health effects; although, trace impurities and microorganisms that are absorbed by iron solids may pose health concerns.

The effects associated with iron contamination can be grouped into two categories:

Aesthetic effects are undesirable tastes or odors. Iron in quantities greater than 0.3 milligrams per liter (mg/L) in drinking water can cause an unpleasant metallic taste and rusty color. Taste is a useful indicator of water quality even though taste-free water is not necessarily safe to drink. Taste is also an indicator of the effectiveness of different kinds of treatments that effectively remove iron from drinking water, such as water softening or reverse osmosis treatment systems. Elevated levels of iron in drinking water can also cause a rusty color that can stain laundry or household. Discolored water is one of the most frequent consumer complaints about drinking water.

Physical effects are damages to water equipment and reduced effectiveness of treatment for other contaminants that may present added costs to operations for water utilities. Corrosivity and staining related to corrosion not only affect the aesthetic quality of water, but may also result in distribution system problems. Among other things, corrosion of distribution system pipes can produce sediment or loose deposits that block water flow.