There are numerous risks. According to US government reports the water you drink from the tap may contain: bacteria, viruses, nitrate, lead and copper. All of these contaminants can cause unpleasant side effects and even serious illness. For more information concerning drinking water: Safe Water: http://www.epa.gov/safewater/dwinfo.htm. Lead in Drinking Water: http://www.epa.gov/safewater/lead/index.html Bottled Water and Water Filters: http://www.nsfconsumer.org/water/bottled_water.asp Home Water Supply Safety: http://www.pueblo.gsa.gov/cic_text/family/healthyhome/water-7.pdf Water Cooler Cleaning: http://www.bnl.gov/bnlweb/pubaf/water/cooler.htm