To collect a tube well water sample, farmers should operate the tube well continuously for at least 30 minutes before taking the sample. Approximately 500 ml to 1 liter of water should be collected in a clean plastic bottle. The bottle should be labeled with the farmer's name, Meri Fasal Mera Byora (MFMB) ID, village name, Killa/Khasra number, mobile number, and borewell depth.