hi there
Bleach in a workplace is considered to be a hazardous chemical, and as such should be stored as such, AND NOT UNDER THE SINK.
the biggest issue is, if your client puts bleach in the toilet bowl, and then a cleaner cleans the toilet with another toileet cleaner chemical, the resultant gas in a confined room can hospitalise a person.
alternatively if the cleaner cleans the toilet, and the client pours bleach in the toilet.
the client might be happy , but ask them to check with their insurance company, they may well change their mind after that discussion.
regards
martin