Most Drano products foam. Dishwashers are sealed environments with spray jets. If the chemical foam rises even an inch, it gets sucked into the spray arms and blown all over your dishes. Even if you rinse the machine ten times, residual caustic film can remain on glasses and baby bottles. That film causes chemical burns to the mouth and esophagus. No amount of clean lasagna is worth that risk.
Panic sets in. You don’t have a plunger handy, and the hardware store is closed. Your eyes scan under the kitchen sink and land on the familiar orange bottle: drano for dishwasher drain clogged
The dishwasher drain hose loops up high under the counter (called a "high loop") before descending into the garbage disposal or sink drain. When you pour chemicals into the dishwasher basin, they don't just flow straight down. They slosh. As the pump tries to engage, it often pushes those undiluted chemicals back up the high loop and out through the air gap (that little chrome cap on your sink). If you have a countertop air gap, a geyser of boiling lye can shoot directly onto your counter, your faucet, or your hands. Most Drano products foam