Over 1.6million people, most of whom are children, die each year from ingesting water contaminated with bacteria, viruses, and parasites. Treatment of drinking water at the point of use (POU)has demonstrated health benefits for people who have access only to microbially contaminated drinking water sources. The ceramic siphon household water filter is one option for POU treatment. In this work, the ceramic siphon filter was evaluated in the laboratory for its ability to reduce indicator microorganisms in test waters. During batch challenge tests, the ceramic siphon filter reduced E. coli in filtered water by 7 log(99.999987%). The filter was not effective for virus removal, with reductions of only 0.12 log(24.0%) observed for coliphage MS-2. In addition, continuous flow dosing system allowing water to constantly run through the filters for extended periods of time daily allowed for determination of changes in microbial reductions over time. E. coli B, MS-2 and fluorescent microspheres (as a surrogate for Cryptosporidium oocysts) were seeded into test water and dosed to filters at 10%, 25%, and 50%) of the filter's volume lifespan. One of the three replicate filters was only tested at 10% and 25% of the filter's volume lifespan because the filter broke prior to reaching its reported 50% volume lifespan. There was a decrease in microbial removal efficacy as the volume of water filtered increased and test filters did not achieve their target volume lifespan before physically failing. The ceramic siphon household water filter is effective in reducing E. coli and fluorescent microsphere surrogates for Cryptosporidium in water, but filter modifications may be needed to achieve acceptable levels of virus removal and to reach the target 7000 liter volume lifespan of the filter.