Water is the single largest input by mass, and the cheapest one to get wrong. Cows drink 4–5 times their body weight in water for every kilogram of milk produced.
Trough sizing Aim for at least 7 cm of trough perimeter per cow. Tipping waterers (40 L capacity, refill in 60 seconds) work well for groups under 20. Larger groups need recirculating troughs of 2–3 m sized for 10% of the herd drinking simultaneously after milking.
Flow rates Pressure-regulated supply is non-negotiable above 200 cows. Aim for 15 L/min per trough refill. A barn of 500 cows can momentarily draw 3,000+ L/min after a milking — undersized pipes throttle this and cows back off the trough.
Water quality Test annually for nitrates, sulphates, iron, and hardness. Iron above 0.3 mg/L tastes bad to cows and reduces intake. Sulphates above 1,000 mg/L cause scours. Hard water (>500 mg/L CaCO3) ruins parlor equipment far faster than people realise.
Heat recovery Plate coolers on the milk line capture roughly 60% of the thermal energy. That preheats drinking water in winter and dramatically reduces parlor wash-water heating costs — payback usually under 24 months.