Sink traps include a 90° elbow and J-shaped bend that retains a small amount of water to form a seal that allows wastewater to pass through but prevents toxic sewer gases and odors from escaping back up through the drain and into a dwelling. These traps also collect debris, which helps prevent blockages and makes it easier to recover items inadvertently flushed down the drain. P-traps connect to pipes under sinks, bathtubs, and showers.