If choosing to use products containing caustic soda, it is vital to follow the manufacturer's instructions on the packaging exactly. General safety protocols include:
Clear the area around the drain. Remove any standing water if possible using a cup or a small jug. If the water is too deep to bail out, this method still works, but it may take a little longer to reach the blockage. Put on your gloves and goggles before you open the container. caustic soda drains unblocking