On Thursday, parts of downtown, west and southwest Columbus, Ohio, all of which use the Dublin Road Water plant, were issued a nitrate warning from the Columbus Division of Water.
The only neighborhoods affected are Grandview Heights, Grove City, Hilliard, Lincoln Village, Marble Cliff, Upper Arlington, Urbancrest and Valleyview.
The increase in nitrate levels is most likely due to storm water runoff from last week's storm.
Those younger than six months or who are pregnant are warned to avoid tap water, and to instead use bottled water.
Boiling water is unadvised because it can actually elevate nitrate levels.
High levels of nitrate can cause shortness of breath and "blue baby syndrome," which is the inability for oxygen to move throughout the body. If a child is not treated for sickness caused by nitrates, they can die.