Plan daily water supply, reserve storage volume, or stored-volume duration from animal count and a suitable per-animal intake. Choose a labeled livestock reference scenario or enter custom intake for goats, poultry and other classes.
Livestock Water Requirement Formula
W = B * M * N
S = W * (1 + b/100) * d
R = C / (W * (1 + b/100))
- W is the total daily water requirement for the herd (gallons/day)
- B is the chosen reference or custom intake for the relevant animal class and conditions (US gallons/animal/day)
- M is an optional user-chosen intake multiplier (blank means1); no universal temperature factor is applied
- N is the number of head
- S is the planned reserve volume (US gallons) for your chosen d days
- b is the waste and evaporation buffer (%)
- R is calculated duration in days for usable stored volume C, assuming constant use and no replenishment
The three modes use the same stated intake and animal count. Daily planned supply includes your chosen allowance; unbuffered daily, 7-day and30-day quantities are also shown. Reserve volume multiplies planned daily supply by your chosen days. Duration divides usable stored water by planned daily supply. These calculations do not determine a safe interval between animal-care or water-system checks.
Daily Water Intake by Species and Temperature
The following labeled examples and ranges appear in NDSU Extension AS1763 (revised March2021), Tables1–5. Conditions differ by species and class. Range upper ends used in some calculator presets are explicit planning choices, not guaranteed maximum requirements.
| Published example | US gal/animal/day |
|---|---|
| Growing beef, 600 lb, 70°F | 7.8 |
| Lactating beef, 900 lb, 70°F | 16.9 |
| Dairy, 50 lb milk/day | 23–27 |
| Idle horse, 1,102 lb, 68°F | 8.2 |
| Lactating ewe, 175+ lb | 2–3 |
| Finishing pig, 100–250 lb | 2–3 |
| Goats, poultry, other classes | Enter suitable measured or advised intake |
Temperature, production, animal size, feed and other conditions affect intake. The following NDSU beef-cattle table illustrates class-specific estimates; it does not justify one temperature multiplier for every species. Its lactating-cow90°F value is reproduced as published, without smoothing or extrapolation. Assess local peak demand and delivery capacity with appropriate agricultural advice.
| Air temperature | Growing 600 lb | Finishing 1,000 lb | Lactating cow |
|---|---|---|---|
| 40 F | 5.3 gal | 8.7 gal | 11.4 gal |
| 60 F | 6.6 gal | 10.8 gal | 14.5 gal |
| 70 F | 7.8 gal | 12.6 gal | 16.9 gal |
| 90 F | 12.7 gal | 20.6 gal | 16.2 gal |
Example Problems
Example1: Select the900 lb lactating beef-cow reference at70°F,16.9 US gal/animal/day. For25 animals and an intake multiplier of1, unbuffered demand is16.9 ×25 =422.5 US gal/day, or2,957.5 US gal over7 unchanged days. A user-chosen10% allowance gives464.75 US gal/day. This reference does not predict intake at85°F.
Example2: Enter a custom planning intake of1.3 US gal/animal/day for100 feeder lambs and a chosen10% allowance. Planned supply is143 US gal/day. A usable1,000 US gal volume gives1,000 /143 ≈6.993 days under unchanged assumptions. This volume estimate does not set a safe refill or animal-check schedule.
FAQ
How much does hot weather increase livestock water needs? The response depends on species, class and conditions. The NDSU600 lb growing-cattle example changes from6.6 US gal/day at60°F to12.7 at90°F. Do not apply that ratio to every animal; use an appropriate scenario or custom intake and check local peak demand.
How do I calculate water for a mixed herd? Run the calculator once per species and add the daily totals together. For example, 20 beef cows at 16.9 gallons and 5 horses at 8.2 gallons in moderate weather gives 338 + 41 = 379 gallons per day. When sizing shared storage, apply the days of reserve and buffer to the combined total rather than to each group separately.
Do animals on pasture need the full calculated amount? Feed moisture and diet affect drinking-water intake, as do health, production and weather. Reference quantities are estimates for stated conditions. Maintain reliable clean-water access, monitor actual use, and seek appropriate advice for your animals.
