Traditional approaches to optimal water quality sensor placement in drinking water distribution networks can be limiting, because they are oriented towards obtaining information and mitigating effects. Approaches optimizing the utility's response to contamination merit wider study and application. The performance of these different approaches is studied and discussed in this paper. It is also shown that practical considerations can impose significant limitations on the performance that can be achieved by a water quality sensor network. These aspects should be taken into account when optimizing sensor placement in a real drinking water distribution network.