Sometimes, people use Drano, run a rinse cycle, and the water drains. They think they’ve won. What actually happened is the heat from the reaction temporarily softened a grease plug, allowing it to move further down the pipe. Now, instead of a clog at the filter, you have a clog three feet downstream in a narrow ¾-inch hose. That new clog is mixed with melted rubber and lye crystals that have re-solidified into a concrete-like mass. At that point, you aren't unclogging it—you are buying a new dishwasher.
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. drano for dishwasher drain clogged
Drano relies on a chemical reaction—usually sodium hydroxide (lye) or sodium hypochlorite (bleach)—that generates intense heat to melt grease and hair. For it to work, the product needs to sit in the clog undisturbed. In a sink, you pour it into standing water. In a dishwasher, that standing water is right at the bottom, surrounding the heating element and the delicate rubber seals. When you pour in Drano, that heat has nowhere to go. It warps the rubber drain hose, melts the plastic pump impeller, and degrades the lower spray arm. You might clear the clog, but you’ve also just melted the internal organs of your machine. Sometimes, people use Drano, run a rinse cycle,