Figure 1

(A) Sampling locations (Bushenyi district). Ishaka; Is, Kashenyi spring 1; Ka, Ground water Kashenyi bridge; Gr, Mutanoga LC1 spring Mu, kyasima spring Bushenyi kigoma; Ky, Nyaruzinga Bushenyi natural raw water; Nya, Ground water; Gr, Orushenyi Ishaka spring; Oru, Kijumo kakaju igara Bushenyi; Ki, Bwangeme B Kakanju Bushenyi; Bwa, kacence Katungu kakajuigara spring gara west Bushenyi; Kac, Katungn Lake Bushenyi; Kat, kyantangu kakajuigara igara west Bushenyi; Ky, Akainje Igara spring West Bushenyi; Aka, keijengye Kakanju Igara East Bushenyi; Kei, Nyamwerande Igara East Bushenyi; Nya, kyemengo spring Igara East Bushenyi; Kye, kagogo nyamwerande Bushenyi; Ka, Rwengoma Kakanju igaraweast Bushenyi well water; Rwe. (B) Sampling locations (Mitooma district). Kirera village well LC1; KiLC1, Kirera 2; Ki2, Nyabubare town council tap; NyTC, Matimba Nyabubare village spring; MN, Rutundu village kahungye; RuK, Karoza Mitooma; KaM, Nkinga town council well water Mitooma; NkTC, Nyakishogwa central LC1 spring; NCLC1. (C) Sampling locations (Sheema district). Kabwohe_Itendero Town council; KTC, Rendez fish pond Kitagata; RFP, Nyakatooma village Kibingo; NVK, Ibanga Kitagata Bundumu; IKB, Kitagata hospital tap water; KHT, Kitagata natural raw water; KNW, Kitagata pond; KP, Kitagata Hot spring; KHS. (D) Sampling locations (Rubirizi district). Butare kyamunhuga well water; BuK, Gongo LC1; GoLC1, Mukayembe Kyamuhunga tap; MK, Ground water kyamuhunga; Ky, Bunyaruguru tap county Rototo Rubirizi; BRR, Lake Ngunguta Rototo Nyarugru Rubirizi; NgRR, Kasoga Rototo spring Rubirizi; KRR, Buhera Parliament village Buyaguru tap Rubirizi; BPB, Lake Chema Rubirizi; ChR, Lake/Cave kamwero Nyarugoro Rubirizi; KNyR, Rubirizi post office tab; POR.