Water Purification Calculator

Calculate emergency water purification needs by household size, duration, and purification method.

Number of people

Duration (days)

Drinking water (gal/person/day)

Sanitation water (gal/person/day)

Purification method (0-4)

Tab to move between fields

Total water needed (gal)

Total water needed (L)211.96

Daily drinking water (gal)4

Daily total water (gal)8

Purification supply needed0.02

5-gal containers needed12

Supply DescriptionLiters of 8.25% unscented sodium hypochlorite bleach

Supply LabelBleach needed (liters)

How to Use This Calculator

Enter Number of People and Duration (days) of the emergency event.
Set Drinking Water (gal/person/day) — minimum is 0.5 gallons, 1 gallon recommended.
Enter Sanitation Water (gal/person/day) for hygiene and cooking.
Select Purification Method (boiling, chlorine tablets, filter, UV, or mixed).
Review Total Water Needed (gallons and liters) and purification material quantities needed.

How the result changes with Number of people

Number of people: Number of people who need purified water.
Duration (days): Number of days water purification is needed.
Drinking water (gal/person/day): FEMA minimum is 1 gal; double in hot climates or with heavy activity.
Sanitation water (gal/person/day): Water for hygiene and sanitation (FEMA recommends at least 1 gal).
Purification method (0-4): 0=Boiling, 1=Bleach, 2=Portable filter, 3=Tablets, 4=UV pen.

Total water needed (gal): Total gallons of purified water needed for the full duration.
Total water needed (L): Total liters of purified water needed.
Daily drinking water (gal): Gallons of drinking water needed per day for everyone.
Daily total water (gal): Daily total including drinking and sanitation.
Purification supply needed: Amount of purification supply (bleach, tablets, time, etc.) based on selected method.
5-gal containers needed: Number of standard 5-gallon water containers for storage.

Identify Input Parameters
4 parameters
Number of people = 4, Duration (days) = 7, Drinking water (gal/person/day) = 1, Sanitation water (gal/person/day) = 1 = 5 input(s) provided
Calculate Total water needed
Total water needed = dailyTotalGal * durationDays
56 = 56
Calculate Total water needed
Total water needed = totalGallonsNeeded * 3.785
211.96 = 211.96
Calculate Daily drinking water
Daily drinking water = people * drinkingGalPerPersonDay
4 = 4