Black and white dairy cows at a wire fence on a green dairy farm
Handy tools

Stock water calculator

Will the water hold out when it turns hot and dry? Add up what your stock drink on a peak summer day, see how long a full tank lasts and whether your pump or spring keeps up.

Rotorua, Bay of Plenty · Photo: AnnWoolliams, CC BY-SA 4.0
1. Which day?

Plan water for the peak day: stock drink the most in hot, dry, windy weather and on dry feed.

2. Your stock

DairyMilking cows
DairyDairy dry stock
BeefBeef cattle (cows, replacements, bulls)
SheepSheep (ewes, hoggets, rams)
DeerDeer (hinds and stags)
GoatsMilking goats
GoatsDry goats
HorsesGrazing horses
HorsesWorking horses

Leave the litres empty to use the guide value shown (grey). Lactating, heavier or young stock on dry feed can drink more - put in your own figure if you know it.

3. Storage and supply (optional)

Time a bucket at the tank inlet to measure the flow: a 10 L bucket filling in 30 seconds is 20 L/min. Solar pumps and springs often give less in a drought - measure in summer.

Showing an example sheep and beef block (TEST numbers, not a real farm) - replace it with your own stock.

Your stock water

Water needed on a hot, dry peak day16,450 L16.5 m³ a day · 115 m³ a week
Flow to keep up over 24 h11.4 L/min685 L an hour
Full tank lasts with no inflow2.7 days
Supply in 24 h a day36,000 L19,550 L a day to spare

The supply keeps up on a hot, dry peak day on these numbers. Troughs still need to refill fast enough when a whole mob drinks at once - check them on a hot afternoon.

  • Beef cattle (cows, replacements, bulls)8,250 L

    150 head × 55.0 L

  • Sheep (ewes, hoggets, rams)8,100 L

    1,800 head × 4.5 L

  • Grazing horses100 L

    2 head × 50.0 L

An average day across the year: about 9,970 L.

Where the numbers come from

  • Guide values: average-day and peak-day litres per head from Reasonable Stock Water Requirements: Guidelines for Resource Consent Applications (Stewart and Rout, Aqualinc / AQUAS for Horizons Regional Council, December 2007). Peak day = the highest single day in the year.
  • Dairy shed: 70 L per milking cow a day for washing and milk cooling, the figure the same report lists from Dexcel and NZSFA. Sheds with plate coolers that recycle water, or green-water yard washing, can use less.
  • Tank and flow: days = tank ÷ litres a day. Flow needed = litres a day ÷ (hours the supply runs × 60). Supply = your flow × 60 × hours.

These are planning figures, not a guarantee: stock need clean, cool water they can always reach, and troughs must refill quickly enough when a whole mob drinks at once. Taking water for stock drinking can be allowed without a resource consent when it has no adverse effect on the environment (Resource Management Act 1991, section 14), but regional plans set their own limits - check with your regional council before a new take, bore or dam. Nothing you type is stored or sent anywhere. Planning feed as well? Try the feed budget calculator or the stock units calculator. Water troubles in a drought? See farm help for the Rural Support Trust.

Need troughs, tanks or a pump?

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