Related by context. Frequent words. (Click for all words.) 63 fluoride 61 chlorine 59 chlorination 57 chlorinated 55 contaminants 55 arsenic 54 groundwater 54 triclosan 54 wastewater 54 Fluoride 53 contaminant 53 fluoridated water 53 fluoridation 52 biosolids 52 sodium chloride 52 atrazine 52 nitrate 52 turbidity 51 nitrates 51 hydrogen sulfide 51 toxic chemicals 51 harmful chemicals 51 chromium 51 bacterial contamination 51 groundwater contamination 50 effluent 50 PFOA 50 toxins 49 toxin 49 septic systems 49 sewage 49 disinfection 49 pesticide 49 raw sewage 49 perchlorate 49 contaminated groundwater 49 hexavalent chromium 49 radium 49 sewage sludge 49 MTBE 49 pesticides 48 septic tanks 48 toxic algae 48 fecal coliform 48 chloride 48 solvents 48 reverse osmosis 47 contamination 47 sulfate 47 biocides 47 bacteria 47 ammonia 47 leachate 47 ethylene glycol 47 wastewater treatment 47 Water Quality 46 potable 46 dissolved oxygen 46 disinfectant 46 mercury 46 stormwater 46 untreated sewage 46 pollutants 46 pH 46 aquifer 46 chemicals 46 PCBs 46 antimicrobials 46 toxic substances 46 coliform bacteria 46 Groundwater 46 leaching 45 sewage treatment 45 brine 45 nontoxic 45 E. coli bacteria 45 nitrogen 45 suspended solids 45 bisphenol 45 phosphorus 45 VOCs 45 pollutant 45 Arsenic 45 radon 45 E. coli 45 sludge 45 filtration 45 catch basins 45 additive 45 fluorine 45 Chlorine 45 water 44 fracking 44 Wastewater 44 neurotoxin 44 Drinking Water 44 harmful bacteria 44 trace amounts 44 alkaline 44 E coli 44 sodium hydroxide