The answer to 'when to replace septic tank' is that most septic tanks need to be replaced every 20-30 years, depending on usage and maintenance. Septic tanks are designed to last several decades, but factors like tank material, soil conditions, and frequency of pumping can impact the tank's lifespan. Signs it's time to replace the septic tank include slow draining sinks/tubs, sewage backups, and the tank failing to properly treat wastewater.
Regularly pumping the septic tank every 3-5 years can extend its life, but eventually the tank and drain field will need to be replaced. Homeowners should plan for this major plumbing project and budget accordingly, as replacing a septic system can cost thousands of dollars. It's best to have a professional plumber or septic contractor evaluate the system and provide recommendations on when to replace the tank.