Related by context. Frequent words. (Click for all words.) 59 hexavalent chromium 58 arsenic 55 chromium 55 perchlorate 55 coliform bacteria 55 benzene 53 dissolved oxygen 53 dioxins 53 turbidity 53 tritium 53 contaminants 53 radium 52 contaminant 52 fluoride 51 PFOA 51 hydrogen sulfide 51 PCBs 50 Arsenic 50 acrylamide 50 E. coli bacteria 50 nitrates 49 ppb 49 nitrate 48 atrazine 48 carcinogen 48 volatile organic compounds 48 dioxin 48 mercury 47 TCE 47 Safe Drinking Water 47 E. coli 47 groundwater contamination 46 chloride 46 chlorine 46 groundwater 46 selenium 46 toxins 46 radioactive iodine 46 ozone 46 toxin 45 pollutants 45 bacterial contamination 45 sulfate 45 cyanobacteria 45 particulates 45 chlorination 45 toxic chemicals 44 C8 44 nitrogen dioxide 44 ozone pollution 44 phthalates 44 carcinogens 44 strontium 44 VOCs 44 BPA 43 pollutant 43 particle pollution 43 phosphorus 43 particulate matter 43 trace amounts 43 concentrations 43 cesium 43 estrogens 43 sulfur dioxide 43 radon 42 MTBE 42 algae blooms 42 contamination 42 nitrogen oxide 42 Drinking Water 42 phosphorous 42 radioactivity 42 cadmium 42 manganese 42 wastewater treatment 42 toxic substances 42 Fluoride 42 wastewater 42 algae bloom 42 harmful substances 42 biosolids 42 harmful chemicals 41 toxicity 41 effluent 41 micrograms 41 carbon monoxide 41 ammonia 41 leachate 41 iodine 41 algae 41 PBDEs 41 particulate 41 sediment 41 antimony 41 septic systems 40 Superfund sites 40 bacteria 40 Clean Water Act 40 Radon 40 aquifer 40 oily fish