by Why does my plumbing seem worse after house guests stay over?
Short Answer: Increased water usage is often exposing a system operating near its limit.
Detailed Answer: Additional showers, toilet flushing, laundry, and dishwashing can reveal capacity problems that remain hidden during normal household usage. Intermittent backups, slow drains, and gurgling commonly worsen during these periods.
Related Questions: Can visitors overload a septic system? What causes septic overload? Why do symptoms worsen during peak water use?