Which is NOT a feature of a septic tank?

Correct option is D

A septic tank is used in areas where public sewage systems are not available, as it provides on-site wastewater treatment.
· (a) Used for personal and small public use – Correct feature, as septic tanks are commonly installed in homes and small institutions.
· (b) Water-tight compartment – Correct feature, as a septic tank must be sealed to prevent leakage and contamination.
· (c) Used where water supply is adequate – Correct, as septic tanks function with limited water but still require a minimum water supply.
· (d) Used where public sewage system is adequate – Incorrect, as septic tanks are used in places where a centralized sewage system is unavailable.