My mother was running her washing machine yesterday evening and as went into its draining cycle, her sink, toilet, and shower erupted water.

She had multiple plumbers come out today, and they've been unable to disclose what the possible issue is. They're suggesting that they jackhammer up the concrete in her bathroom to find the culprit, and tossing out "over $1000" loose quotes.

Any clue what would have caused this issue?