Blocked With Caustic Soda: Drain
Put on rubber gloves (dish gloves are fine), safety goggles (not just glasses), and old long sleeves. Caustic soda burns are no joke.
If the water is just sitting there, you need to lower the pH before you can work. Very slowly add white vinegar or citric acid to the standing water (roughly 1 cup vinegar per gallon of water). It will fizz. Wait 10 minutes. This neutralizes the caustic soda into a salty water solution. drain blocked with caustic soda
Don’t panic. Here is exactly how to troubleshoot this safely. Put on rubber gloves (dish gloves are fine),