I'm assuming that this ...

I'm assuming that this question relates to a boiler system that was designed to recover >95% of the condensate from boiler steam. About the only boilers I can recall that do not recover steam condensate are steam driven farm equipment and steam railroad engines.

Condensate that is not recovered is a heat loss from the system and may affect the costs for treating and discharging waste waters. Lost condensate must be replaced by treating and purifying the plants raw water supply, increasing the load and operating costs on the makeup water system. When considering the costs of minimizing condensate loss (plugging leaks, assuring that heater vents are working properly, etc), these should be balanced against the costs of providing fresh makeup.