Plan at least 20 liters of water per person per day for drinking, cooking and basic hygiene, and 50-80 liters per person per day for a comfortable community that also washes laundry and waters a garden. Twenty liters is one 20-liter bucket per person per day, and 80 liters is four buckets, so the budget is also a measure of how much carrying each person does.
Part of Community Water System
A per capita water budget is the number of liters one person is allotted per day. It is the multiplier that turns a head count into the daily demand of a system.
The Budget Has Two Levels, And The Gap Between Them Is Mostly Washing And Growing Food
The community water system page gives two figures. The first is the floor: a minimum of 20 liters per day per person covers drinking, cooking and basic hygiene. The second is 50-80 liters per day, for a community that also does laundry and irrigates a garden. Animals and large gardens are counted separately (Livestock and Irrigation).
Other pages in this wiki give other tiers, and they are different scales, not corrections. Distribution Network lists 3-5 liters as survival only, 15-20 as basic hygiene and 30-50 as a comfortable household, and sizes its example village at 30 liters. Use one scale consistently inside a single design, and say which one you used.
Use also depends on the walk. Water that must be carried a long way is used sparingly; water from a tap a short distance away tends to be used more freely. A design that assumes the carried-water habit and then installs close taps can find demand higher than planned.
What You Need
- A head count — present, and expected over the pipe’s life
- A choice of level — minimum or comfortable, made before the source is picked
- A bucket, to turn liters into a feel for the work
Method: Choose A Level, Then Multiply
Step 1: Choose the level the dry-season source can honestly support. If the source gives less than the comfortable total in its worst month, design to the minimum and treat the rest as a bonus.
Step 2: Multiply people × liters per person per day.
Step 3: Convert to buckets so the community understands the number: divide by 20.
Worked Example: A Group Of Thirty
Inputs: 30 people; 20 L bucket.
- Minimum: 30 × 20 = 600 L/day, which is 600 ÷ 20 = 30 buckets.
- Comfortable, low: 30 × 50 = 1,500 L/day, which is 75 buckets.
- Comfortable, high: 30 × 80 = 2,400 L/day, which is 120 buckets.
If the nearest tap is 200 m away, each trip is 400 m there and back. At 2.5 buckets per person per day (50 L) that is 2.5 × 400 = 1,000 m of walking each day for each person, with the loaded half carrying about 20 kg. The same person at 4 buckets (80 L) walks 1,600 m.
Common Mistakes
- Using the comfortable figure when the source gives only the minimum. The tap runs dry in the dry season and the shortfall lands on drinking water.
- Mixing scales. Taking 30 L from one page and a 50 L tier from another double-counts in the same sum.
- Forgetting growth. A pipe is hard to enlarge once buried.
Safety
Cut washing and gardens first, never drinking and cooking
When water is short, ration the large uses before the small ones. Reducing hygiene water below the basic level raises the risk of the diarrhoeal illnesses a clean supply is built to prevent. Keep the 20-liter minimum for drinking, cooking and handwashing as the last thing to be cut.
What’s Next
- Learn next: Demand Calculation — adding animals, garden and leakage to the head count
- Combine with: Standpipes and Taps — placing the taps so the walk is short