Water productivity and watermelon (Citrullus lanatus Thunb.) yield were measured as quantity of fruit produced (kg) per unit of water consumed (m3) in plots established by direct sowing (SD) or transplant, with or without plastic mulch, and irrigated considering two irrigation criteria using underground drip irrigation. Results show that establishing the crop by transplanting at “initial handlebar” (IG) or “two true leaves” (HV) stages, with plastic mulch (CA), and irrigated at 50 % pan evaporation (E), productivity was 9.0 and 9.1 kg×m-3, respectively. In contrast, crop established by direct sowing, without mulch, and irrigated at 50 % E had a water productivity of 4.0 kg×m-3. The highest fruit yields of 52.0 and 51.5 t×ha-1 were obtained in plots established with HV and IG respectively, with mulch, and irrigated at 60 % E. The lowest yield (22.7 t×ha-1) was obtained in plots established by direct sowing, no mulch, and irrigated at 60 % E. Plastic mulch allowed harvest to begin seven days earlier than control treatments. Using transplant at IG allowed harvest to begin 7 to 14 days earlier than transplant at HV or SD, and 22 days earlier than treatments with direct sowing and no plastic mulch.