Link: https://imgur.com/a/9JNPnl1 (in case the BBCode doesn't work).
The leak on the first floor produced a wet ceiling in our living room, and sometimes drops of water would form and fall. So the drops fall in the bucket and a microphone records each drop and a computerprogram (written by MrMcGyver himself) records the time between drops. And then he would correlate the speed of droplet formation to certain actions in the bathroom (showering, flushing the toilet etc).
Turns out the leak is in the tubes that connect the sink AND the washing machine drainage to the general drainage system. The shower and toilet are downstream from the leak, so we CAN continue to take showers (ERE people who will see me tomorrow in Amsterdam will be relieved to know), but we CANNOT wash our hands or brush our teeth upstairs (will do so downstairs) and we might want to limit the usage of the washing machine until we can have the problem fixed.
We will have the problem fixed by professionals because generally speaking we're not people who build their own bathroom.