Plain water has zero calories — the simplest entry in any tracker. A meta-analysis (Muckelbauer et al., Am J Clin Nutr 2013) found ~1 L extra water daily added 1–2 kg of weight loss in dieting adults. The "drink water before meals" tip has real evidence behind it.
How should I track Water, tap?
Liquid calories from Water, tap are easy to overlook because drinks do not trigger the same fullness signals as solid food. A meta-analysis (Wehling & Lusher, Am J Clin Nutr 2021) confirmed that people underreport beverage intake more than solid food. Most people pour 30–50% more than the label serving size without realizing it. Use a kitchen scale to weigh your glass or bottle once — you will know your exact pour going forward. This one calibration step can save you from hundreds of untracked calories per week.