Some people with dementia forget to turn off the faucets when leaving the bathroom or kitchen. If the drain is plugged or has debris, the sink or tub will overflow. An overflowing sink or tub not only causes emotional distress, but flooded rooms can be difficult to mop up. Flooding can also cause building damage and increase eviction risk for renters.
The good news is that there are many things you can do to reduce flooding. Many sinks and tubs already have overflow drains built in. And there are special valves you can install on your bathtub and sink pipes that automatically turn the water off when it reaches a certain level. And automatic turn off faucets can be installed at the sink.
As always, see which one(s) work best for your situation.