In the first hour after a water test fails, take a sample before changing anything, warn the whole community to boil drinking water, isolate the suspect part of the system if there is an alternative, and arrange safe water for the vulnerable first. The need is small and plannable: 20 people at 3-5 liters each for drinking come to 60-100 liters a day, which is five batches in a 20 liter pot.
Part of Community Water Testing
Immediate actions are the first steps, in the first hours, that protect a community from water that may be contaminated while the cause is still unknown.
The First Hour Protects People; The Investigation Comes Second
The community water testing page begins its response with a boil-water advisory issued immediately, then increased treatment, then retesting. This page adds what to do in the same hour, in order, so that the evidence is kept and the people are covered.
| Order | Action | Why |
|---|---|---|
| 1 | Take samples where the failure was found and at the source and tank outlet, before flushing, chlorinating or cleaning | The evidence is gone once you change the water |
| 2 | Warn the community: boil all drinking water | People are drinking it now |
| 3 | Isolate the suspect section: close the source, tank or branch valve if another source or stored safe water exists | Stops spreading it (Isolation Valves) |
| 4 | Supply safe water for the vulnerable first: infants, the sick, the old | They are hurt first |
| 5 | Increase treatment in line with the written procedure, then measure the residual | See Responding to Failures |
| 6 | Tell the health lead if people are ill | They can look for cases (Disease Surveillance) |
| 7 | Start the investigation | Source Investigation |
Sources Of Safe Water While The Supply Is Suspect
- Boiling. A rolling boil for 1 minute below 2,000 m, 3 minutes above (Rolling Boil).
- Chlorine treatment of clear water at home, using the dose table in Chemical Treatment with the contact time stated there. Cloudy water must be cleared first.
- Sunlight in clear PET bottles, 6 hours of strong sun, from the rack if one exists (SODIS Batch System).
- Previously treated stored water, if it was stored in a clean, closed container before the event.
Water from the suspect supply can be treated by chlorine or sunlight only if it is clear, and boiling is the most dependable method while the cause is unknown.
What You Need
- A written emergency plan with named people and a phone tree, or the equivalent
- Pots, fuel and covered storage containers
- Bottles and a sunny surface, if you rely on sunlight
- Test kit and log
Method: A Checklist You Can Run Without Thinking
Step 1: Sample. Label the time, place and who took it.
Step 2: Announce. Send runners, ring the bell, post notices. Say: what is wrong, boil for the stated time, do not drink from the taps unboiled, and where to go for help.
Step 3: Isolate when you have safe water elsewhere. Close valves slowly, since a fast closure can add about 3 bar to the line pressure.
Step 4: Provide water. Count pots and fuel.
Step 5: Look after people. Anyone with diarrhoea loses a lot of water and needs safe fluids; send for the healer and keep them away from food preparation and the water source.
Step 6: Hold a short meeting at the end of the hour: who does what next, when to retest, who talks to the community.
Worked Example: How Much Boiling?
Inputs: 20 people; drinking water only, at 3-5 L per person per day (the survival tier in Distribution Network); a 20 L pot.
- Water needed: 20 × 3 = 60 L up to 20 × 5 = 100 L per day.
- Pots: 60 ÷ 20 = 3 up to 100 ÷ 20 = 5 batches a day.
If cooking is included at 20 L per person (the minimum for drinking, cooking and basic hygiene): 20 × 20 = 400 L a day, which is 400 ÷ 20 = 20 batches. That is a lot of fuel and time, which is why the first step is to boil for drinking and the youngest and sickest, and to keep hand-washing water for later.
A sunlight rack of 50-100 bottles of 2 L provides 100-200 L a day in good sun, so it can cover 60-100 L of drinking water alone, with sun.
Common Mistakes
- Flushing or chlorinating before taking a sample.
- Shutting the only source with no safe water ready. Plan the water first.
- Boiling too briefly. The time is the point.
- Putting boiled water back into a dirty container.
- Forgetting the sick person’s carer. They spread it.
Safety
A fast valve closure and a poor boil both hurt
Close valves slowly: a sudden closure can burst a pipe. Keep children away from boiling pots. Store boiled water covered and in clean containers. Never mix chlorine with acids, vinegar or ammonia products when treating water or cleaning containers: they release toxic gas. If you must enter a tank or well, use ventilation, a harness on a line held by a person outside, and the rule that the person outside never goes in after a collapsed worker; never test the air with a flame.
What’s Next
- Learn next: Source Investigation — finding where the contamination entered
- Combine with: Responding to Failures — the full sequence and when to lift the advisory