Home🌾 Crop🐄 Livestock🚜 Machinery💧 Irrigation💰 Finance🌱 SoilAll Tools
Home › Irrigation › Farm Water Security

🔒 Farm Water Security Calculator — Days of Supply Remaining

Calculate how many days your water supply will last for livestock, irrigation and household use. Plan for drought.

Quick answer: Days supply = Total stored water ÷ Daily use. Example: 5 ML dam ÷ (100 cattle × 80L = 8,000 L/day) = 625 days. Subtract evaporation: up to 10 ML lost from 1ha dam over summer.

🔒 Calculate Water Security

Use Dam Volume Calculator to estimate
Rainwater and header tanks
If bore is reliable, add to supply
Beef: 80L/day, Dairy: 150L/day
12 L/day per sheep
Family + garden
—
Days of Supply (no evaporation)
—
Total Storage (ML)
—
Daily Use (L/day)

📐 How Water Security Is Calculated

Total storage (ML) = Dam + Tanks + (Bore L/day × 90 days ÷ 1,000,000)
Daily use (L) = (Cattle × 80) + (Sheep × 12) + Household
Days supply = (Total ML × 1,000,000) ÷ Daily use
  1. Measure all storage — dams, tanks, bore yield
  2. Calculate daily demand — livestock + household
  3. Divide storage by demand — gives days supply
  4. Subtract evaporation — can halve summer supply

📊 Worked Example

5 ML dam, 0.1 ML tanks, 100 cattle, 500 sheep, household 800L/day.

Total storage = 5.1 ML = 5,100,000 L
Daily use = (100×80) + (500×12) + 800 = 8,000 + 6,000 + 800 = 14,800 L/day
Days = 5,100,000 ÷ 14,800 = 345 days

Enough for nearly a year. But evaporation of 5mm/day from 0.5ha dam = 2,500 L/day loss in summer, reducing supply significantly.

❓ Frequently Asked Questions

Days supply = (Dam volume + Tank volume) ÷ Daily water use. Example: 5 ML ÷ (100 cattle × 80L = 8,000 L/day) = 625 days.

Cattle: 50-100 L/head/day. Sheep: 10-15 L. Household: 500-1,000 L/day. Irrigation: 5-15 ML/ha/year. Firefighting: minimum 20,000 L dedicated.

Add storage (dams, tanks). De-silt existing dams. Install rainwater tanks on sheds. Connect multiple water sources. Reduce evaporation with shade.

Summer: 4-8mm/day, Winter: 1-3mm/day. Annual average: 1,500-2,000mm. A 1ha dam loses 15-20 ML/year to evaporation — often more than stock use.

🔗 Related Calculators

🏞️ Dam Volume💧 Irrigation Water☀️ Drought Feeding