U.S. tap water is generally safe and high quality. But that doesn’t mean every glass tastes the same, or that every building’s plumbing delivers identical water to the faucet. That uncertainty has fueled a booming market for water filters, from simple pitcher models to multi-thousand-dollar reverse osmosis systems. Yet experts say most American households don’t need extensive treatment. The challenge is knowing how to decide whether you need a filter. Under the Safe Drinking Water Act, the