Monitoring recreational waters for human health risks is a necessary but time- and cost-intensive process for health agencies. Budget constraints result in choices that may reduce the coverage of monitoring to levels that are below what is optimally desired. This is especially true if the area requiring monitoring is large and the funds for providing that monitoring are inadequate. For some agencies the feasibility of carrying out a comprehensive sampling program, (e.g. daily monitoring), is not an option, even though more frequent sampling of recreational waters may provide a more accurate picture of bacteria levels at a given location than sampling less often. As sampling frequency is reduced, it is not always clear what is lost in terms of detecting high bacteria levels. Sampling less often yields less accurate results as compared to daily sampling, but how much less accurate has not been quantified. In this study there is a direct relationship between the frequency of sampling and the ability to detect exceedances of an established threshold. Not surprisingly, sampling every other day reduces the ability to detect an exceedance by half, and sampling once a week by one-seventh. Following up exceedances with additional sampling can increase the effectiveness of a sampling regime; the increase in additional sampling results in a proportionally larger increase in effectiveness. These results quantify for the first time the reduction in accuracy when sampling is not conducted on a daily basis. They also demonstrate that, by refining sampling regimes, health agencies may efficiently increase their ability to protect public health. With the cost of monitoring programs often a limiting factor in protecting public health, the information provided here will help agencies to make better informed decisions about the allocation of their limited resources.