What can be in well water

What each one is, how it gets into wells, how to test for it and how to get it out.

• ArsenicArsenic in private wells comes from natural rock. It has no taste or smell, the EPA limit is 10 µg/L, and a kitchen reverse osmosis filter removes most of it.
• Coliform bacteriaA positive coliform test means surface water has a way into your well. E. coli means waste is getting in. Here's what each result means and how to fix it.
• HardnessHard well water leaves scale and soap scum but isn't a health risk. Here's the USGS hardness scale in mg/L and grains per gallon, and what a softener costs.
• IronIron causes orange-brown stains and a metallic taste in well water. It isn't a health risk at normal levels. Here's how to test it and which filter fits.
• LeadLead in well water comes from plumbing, brass fixtures and old pump parts. Babies, kids and pregnant women face the most risk. Here's how to test and fix it.
• ManganeseManganese leaves black stains, and at higher levels it's a health concern for babies. The EPA's health advisory is 0.3 mg/L. Here's how to test and remove it.
• NitrateNitrate gets into wells from fertilizer, manure and septic systems. The EPA limit is 10 mg/L, babies are most at risk, and boiling makes it stronger.
• PFASPFAS are long-lasting chemicals found near factories, waste sites and foam spills. The EPA limit for PFOA and PFOS is 4.0 ng/L. Here's how to test and filter.
• RadonRadon dissolves into wells from granite and similar rock. Most of the risk comes from breathing it after it leaves the water. Here's how to test and treat it.
• UraniumUranium dissolves into wells from granite and the sand and gravel worn from it. The EPA limit is 30 µg/L. Years of drinking it can harm the kidneys.