ESTIMATING SEWAGE FLOWS FOR CLUSTER DEVELOPMENTS

Cluster system designers are hampered by the lack of an efficient and effective way to estimate wastewater flows. This paper attempts to answer the question “how should wastewater flow be estimated for multi-home cluster systems?”. The author used 591 consecutive days of daily water meter readings at a single family residence in Lake Alfred, Florida to represent water use from two-home, five-home, ten-home, twenty home, fifty home and 100-home clusters. Similar to findings of Stephens (2007), smaller sample sizes exhibited higher variability than larger samples, because an individual's daily peak usage is balanced by others using less than average water use that day. Based on the data presented, the author suggests continuing to use prescriptive per home water use estimates for up to 5 home cluster systems. At 100 homes, the Estimated Dwelling Unit concept should be used. Between 5 and 100 homes a linear extrapolation between the estimate developed using local onsite system regulation and the applicable EDU estimate should be used, proportional to the actual number of homes in the cluster.