The ability of household pitcher-style water purifiers to remove microcystins depends on filtration rate and activated carbon source

Toxic cyanobacterial blooms are a global threat to human health due to contamination of drinking water. To ensure public safety, water treatment plants must have the capability to remove cyanotoxins from water. Recently, however, there have been several instances when microcystins, a common group of cyanotoxins, have been detected in tap water. This research investigated if commercially available pitcher-style water purifiers were able to remove microcystins from water. Microcystins were extracted from two naturally occurring blooms in Lake Erie, diluted to initial concentrations ranging from 1 to 5 μg/L, and then subjected to three purifier types. Results showed that the purifier with the fastest percolation rate (126 seconds/L) and a filter cartridge comprised solely of coconut-based activated carbon removed 50% or less of the microcystins, while the purifier with the slowest percolation rate (374 seconds/L) and a blend of activated carbon decreased microcystins to below detectable levels (<0.10 μg/L) in all experiments. Thus, pitcher-style purifiers with slow percolation rates and composed of a blend of active carbon can provide an additional layer of protection against microcystins; however, it is recommended that consumers switch water sources when cyanotoxins are confirmed to be in tap water.