In an effort to evaluate the suitability of tire chips as structural fill in residential onsite septic distribution systems (OSDS), two new homes in Jackson County, Indiana, were selected for hydrologic monitoring and water-quality sampling. One of the sites used tire chips as a substitute for rock aggregate in the septic system absorption field; the other site used conventional rock aggregate in the absorption field and was used as a control site. Both sites were instrumented for continuous hydrologic monitoring, and both systems were sampled quarterly for water-quality analyses. Monitoring continued for 13 months beginning in May 2006 and ending in June 2007. The results of hydrologic and water-quality monitoring suggests that the tire chips in the residential onsite septic system performed as well, or better, than the conventional aggregate system. In most months of the year, the vertical attenuation of wastewater components was superior in the Tire Chip system compared to the performance of the Control system. Additional supporting data files (hydrology, micrometeorology, and chemistry data spreadsheets) are available for this open-file study. To request a downloadable data archive, or alternatively a CD-ROM, please contact our publication sales office.