WHO 1958	-
WHO 1963	-
WHO 1971	Drinking-water should not contain amoebic cyst, Schistosoma spp., and Dracunculus medinensis
WHO 1984 and 1985	Drinking-water should not contain protozoa (Entamoeba histolytica, Giardia spp. and Balantidium coli.) or infective stages of helminthes (Dracunculus medinensis, Schistosoma mansoni, S. haematobium, S. intercalatum, Ascaris lumbricoides, Trichuris trichiura, Strongyloides stercoralts, and Ancylostoma duodenale)
WHO 1993 and 1996	Drinking-water should not contain protozoa (Giardia spp., Cryptosporidium spp., Entamoeba histolytica, and Naegleria fowleri Acanthamoeba spp., and Balantidium coli.). Helminthes (Dracunculus medinensis, Fasciola spp., Echinococcus spp., Schistosoma mansoni, S. haematobium, S. intercalatum, Spirometra spp., Ascaris lumbricoides, Trichuris, Toxocara, Necator amencanus, Ancylostoma duodenale, Strongyloides stercoralts and Taenia solium).
WHO 1998	-
WHO 2002	Drinking-water should not contain protozoa (Entamoeba histolytica, and Naegleria fowleri Acanthamoeba spp., Cryptosporidium parvum, Giardia intestinalis, Cyclospora cayetanensis and Toxoplasma gondii).
WHO 2004 and 2006	Drinking-water should not contain protozoa: Acanthamoeba spp. (A. castellanii, A. polyphaga and A. culbertsoni), Giardia intestinalis, Cryptosporidium parvum, Microsporidia, Cyclospora cayetanensis, Entamoeba histolytica, Isospora belli, Balantidium coli, Naegleria fowleri and Toxoplasma gondii). Helminthes Fasciola spp. (F. hepatica and F. gigantica), Dracunculus medinensis Strongyloides stercoralts, Ascaris lumbricoides, Trichuris trichiura and Schistosoma spp. (S. mansoni, S. haematobium, S. intercalatum).
WHO 2008	Drinking-water should not contain protozoa: Acanthamoeba spp. (A. castellanii, A. polyphaga and A. culbertsoni), Microsporidia, Entamoeba histolytica, Balantidium coli, Cryptosporidium parvum, Cyclospora cayetanensis, Isospora belli, Giardia intestinalis, Naegleria fowleri and Toxoplasma gondii). Helminthes: Fasciola spp. (F. hepatica and F. gigantica), Dracunculus medinensis, Ascaris lumbricoides, Trichuris trichiura, and Schistosoma spp. (S. mansoni, S. haematobium, S. intercalatum). Free-living nematodes hookworms (Necator americanus, Ancylostoma duodenal) and threadworms (Strongyloides stercoralis).
WHO 2011	Drinking-water should not contain protozoa: Acanthamoeba (A. castellanii, A. polyphaga and A. culbertsoni), Cyclospora cayetanensis, Balantidium coli, Entamoeba histolytica, Cryptosporidium hominis/parvum, Giardia intestinalis, Naegleria fowleri, Blastocysts hominis, Isospora belli, Microsporidia and Toxoplasma gondii). Helminthes: Dracunculus medinensis and Fasciola spp. (F. hepatica and F. gigantica), Ascaris lumbricoides, Trichuris trichiura, Schistosoma spp. (S. mansoni, S. haematobium, S. intercalatum). Free-living nematodes other than (Dracunculus medinensis). Free-living nematodes hookworms (Necator americanus an Ancylostoma duodenal) and threadworms (Strongyloides stercoralis).
WHO 2017	Drinking-water should not contain protozoa: Acanthamoeba (A. castellanii, A. polyphaga and A. culbertsoni), Cyclospora cayetanensis, Giardia intestinalis, Balantidium coli, Cryptosporidium hominis/parvum, Entamoeba histolytica, Blastocysts hominis, Naegleria fowleri, Isospora belli, Microsporidia and Toxoplasma gondii). Helminthes: Dracunculus medinensis, Fasciola spp. (F. hepatica and F. gigantica), Ascaris lumbricoides, Trichuris trichiura, Schistosoma spp. (S. haematobium, S. intercalatum, S. japonicum, S. mekongi and S. mansoni). Free-living nematodes other than (Dracunculus medinensis). Free-living nematodes hookworms (Necator americanus and Ancylostoma duodenal) and threadworms (Strongyloides stercoralis).