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Water Purification Calculator

Plan water treatment for your outdoor trip

Water Needed

18 L

Gallons

4.8

Time

18 min

Total Water Needed

18 L

4.8 gallons

Treatment Time

18 min

Est. Cost

$0.10

Example Calculations

12 hikers, 3-day trip with pump filter

Inputs

People2
Days3
L/Person/Day3
MethodPump Filter

Result

Total Water18 L (4.8 gal)
Treatment Time18 min

2 × 3 × 3 = 18 L. Pump filter at 1 L/min = 18 minutes total treatment time.

2Solo hiker, 5-day trip with UV

Inputs

People1
Days5
L/Person/Day3
MethodUV Purifier

Result

Total Water15 L (4.0 gal)

1 × 5 × 3 = 15 L. UV at 1 L/min = 15 minutes.

Frequently Asked Questions

Q

How much water do I need per day hiking?

Plan 2–4 liters per person per day depending on temperature and exertion. Hot weather or strenuous hiking can require 4+ liters.

  • Moderate weather, flat terrain: 2–3 L/day
  • Hot weather or steep terrain: 3–4 L/day
  • Desert hiking: 4–6 L/day
  • Add 1 L/day for cooking if using dehydrated meals
ConditionLiters/DayGallons/Day
Cool, easy2–2.5 L0.5–0.7 gal
Moderate3 L0.8 gal
Hot, strenuous4+ L1+ gal
Q

Which water purification method is fastest?

UV purifiers (SteriPEN) and pump filters treat 1 liter per minute. Chemical tablets take 30+ minutes. Boiling takes 5–10 minutes per liter including heat-up time.

  • Pump filter: 1 L/min, removes bacteria and protozoa
  • UV purifier: 1 L/min, kills viruses too
  • Chemical tablets: 30 min wait, lightweight backup
  • Boiling: 100% effective but slow and fuel-intensive
Q

Do I need to treat all backcountry water?

Yes. Even clear mountain streams can contain Giardia, Cryptosporidium, and bacteria. Always treat water from natural sources unless it is a tested and maintained spring.

  • Giardia cysts survive weeks in cold water
  • Crypto is resistant to iodine — use filters or UV
  • Springs can be contaminated by upstream animal activity
  • Tap water at campgrounds is generally safe
Q

How do chemical purification tablets work?

Chlorine dioxide or iodine tablets kill bacteria, viruses, and protozoa. Drop one tablet per liter, wait 30 minutes (4 hours for Crypto with chlorine dioxide).

  • Chlorine dioxide: effective against all pathogens including Crypto
  • Iodine: does NOT kill Cryptosporidium
  • Taste: chlorine dioxide tastes better than iodine
  • Weight: tablets weigh almost nothing — great backup method

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Last Updated: Mar 19, 2026

This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered professional financial, medical, legal, or other advice. Always consult a qualified professional before making important decisions. UseCalcPro is not responsible for any actions taken based on calculator results.

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