Better Water Information

What is the Point-of-Collection Chlorination Model?

The Point-of-Collection Chlorination Dispenser is an evidence-backed public health intervention designed by Nobel laureates (Kremer, Miguel, et al.) and scaled globally by Evidence Action (Dispensers for Safe Water).

Rather than relying on individual households to purchase, measure, and dose chlorine bleach at home (which suffers from low compliance $<15%$), a heavy-duty, calibrated chlorine dispenser is mounted directly beside communal water sources (boreholes, shallow wells, spring boxes, or kiosks).

   [Communal Hand Pump / Spring Outlet]
                     |
                     v
   [Community User Fills 20L Jerrycan]
                     |
                     v
   [User Turns Dispenser Valve (1 Click)]
   ===> Injects Exactly 3.0 mL of Dilute Sodium Hypochlorite (1.25% NaOCl)
                     |
                     v
   [User Walks Home (20-30 min Transit Time)]
   ===> Chlorine Agitates & Sanitizes Water During Transit
                     |
                     v
   [Safe Residual Protection (0.2–0.5 mg/L Free Chlorine)]
   ===> Prevents Re-contamination in the Home for up to 72 Hours

Why GiveWell Ranks Chlorination as Top-Tier Impact

Rigorous randomized controlled trials (RCTs) across Kenya, Uganda, and Malawi demonstrated that point-of-collection dispensers increase sustained community chlorination adoption from $<10%$ to over 50–60%, resulting in a $\sim 30%$ reduction in all-cause child mortality under age 5.

Key Advantages:

Free to the User: Chlorine is provided free at the point of collection, eliminating poverty barriers.
Standardized Dosing: A precision plastic valve dispenses the exact dosage (typically $3.0\text{ mL}$ for a standard 20L jerrycan), preventing overpowering chemical tastes or ineffective under-dosing.
Residual Disinfection: Unlike UV or mechanical filters, chlorine leaves a free chlorine residual that actively protects water from re-contamination by dirty hands, unwashed cups, and open storage buckets in the home.
Extreme Cost Efficiency: Costs approximately $1.00 to $1.50 per person per year to maintain an active supply chain of sodium hypochlorite.

Technical Specifications

Parameter	Specification
Active Chemical	Dilute Sodium Hypochlorite ($1.25%\text{ NaOCl}$)
Dosing Volume	$3.0\text{ mL} \pm 0.2\text{ mL}$ per 20-Liter container
Target Free Chlorine Residual	$0.2\text{ to } 0.5\text{ mg/L}$ after 24 hours of household storage
Dispenser Tank Capacity	$5.0\text{ Liters}$ (sufficient for $\sim 1,600$ jerrycan fills / 32,000 Liters)
Material Construction	UV-stabilized virgin HDPE casing with tamper-proof padlock and brass/stainless internal ball valve

Limitations & Pre-Treatment Requirements

High Turbidity Interference: High suspended solids ($>10\text{ NTU}$) or organic matter consume chlorine rapidly (chlorine demand), reducing disinfection efficiency. Turbid surface water requires upstream sedimentation or roughing filtration before chlorination.
Chemical Contaminants: Chlorine kills 99.99% of bacteria and viruses, but does not remove dissolved heavy metals, fluorides, nitrates, or chemical pesticides.