Dogs drink water wherever they happen to find it — a puddle, a pond, a toilet. But the stuff in their actual water bowls almost always comes from the same tap their owners use. When that water is contaminated, both dogs and humans may suffer. The risk is especially high for the 15 million American households that rely on private wells, according to a new Virginia Tech study in the journal PLOS Water. In dog drinking water sampled from wells across the country, 64 percent contained excessive levels of at least one potentially toxic heavy metal, such as lead, iron, sulfur, or arsenic. … Because heavy metal contaminants are often tasteless, odorless, and invisible, homeowners may not know there’s something in the water — until their dog gets sick.