Two seperate issues:
- Fresh water side (ie turn the main off): This has absolutely nothing to do with cockroaches but in the event of a leak, it won't continue to leak for days. Compared to going to work for the day, if you dry out a wet floor in a few hours, it's likely to do little if any harm. Have it soaked for a month and it's likely trashed.
- Sewer side: It's unlikley you have cockroaches in your sewer pipes but possible (septic system is highly unlikely as decomposition keeps oxygen levels down. city sewer still low probability but possible). As long as the P-traps don't dry out, not an issue. If it's winter time, I would go with some antifeeze so the P-traps don't bust when they freeze. Never had a problem with it evaporating out.
