When Cyclone Idai destroyed the water infrastructure in Mozambique (2019), international relief teams distributed millions of SDIC tablets to prevent cholera. When Turkish and Syrian earthquake survivors needed clean water (2023), SDIC was again the front-line tool. This guide explains why — and how to use it correctly.
1. Why SDIC for Potable Water?
- Fast-acting: 30 minutes contact time kills 99.99% of E. coli, cholera, salmonella
- Neutral pH: does not alter drinking water taste or corrode pipes
- Stable in tablet form: 3-year shelf life, easy to transport in emergencies
- NSF/ANSI 60 listed: approved for drinking water contact in USA, Canada, EU
- Cost-efficient: ~US$0.02 to treat 1000 liters
2. WHO Recommended Dosage
| Water Source | SDIC Dose (mg/L) | Contact Time | Free Cl Residual Target |
|---|---|---|---|
| Clear tap water (safety top-up) | 1.5 mg/L | 30 min | 0.5 mg/L |
| Clear rainwater | 2.0 mg/L | 30 min | 0.5 mg/L |
| Turbid water (river, pond) – filtered first | 4.0 mg/L | 60 min | 1.0 mg/L |
| Highly contaminated (post-disaster) | 8.0 mg/L | 60 min | 1.0-2.0 mg/L |
3. Tablet Dosing Chart
Using standard 8.5 mg SDIC tablets (Aquatabs style):
- 1 tablet + 1 liter = 8.5 mg/L (heavy disinfection)
- 1 tablet + 4 liters = 2.1 mg/L (standard)
- 1 tablet + 20 liters = 0.4 mg/L (top-up)
Using 200 mg SDIC tablets (Presept style):
- 1 tablet + 100 liters = 2 mg/L (household drum)
- 1 tablet + 500 liters = 0.4 mg/L (tank top-up)
4. Step-by-Step Procedure
- Filter first if water is visibly turbid (cloth, sand filter, or ceramic filter)
- Measure water volume accurately (guessing over-doses by 3-5×)
- Add SDIC tablet(s) using tweezers or gloves (never bare hands)
- Stir for 30 seconds to dissolve tablet completely
- Wait minimum 30 minutes before drinking (60 minutes for cold water < 15°C)
- Test residual chlorine with DPD test kit (target: 0.2-2.0 mg/L free Cl)
- Store in covered container; consume within 24 hours
5. Common Scenarios
Emergency Household Storage (200L drum)
Dose: 1× 200mg SDIC tablet per 100L. Wait 30 min. Redose if kept > 3 days.
Refugee Camp Water Truck (10 m3)
Dose: 5g SDIC powder per m3 (2.5 mg/L active Cl). Test at outlet with DPD.
Small Village Well (50 m3)
Well shock: 250g SDIC (100 mg/L) → wait 12 hours → flush → return to 2 mg/L feed
Hospital Kitchen Filter
SDIC at inlet: 1.5 mg/L continuous dosing via chemical feed pump. Verify residual at faucet.
6. Regulatory Compliance
- USA: NSF/ANSI 60 listing required; check EPA MCL 4 mg/L Cl
- EU: Biocidal Products Regulation (BPR) Article 95 list; PT 5
- WHO: Guideline value 5 mg/L; taste threshold 0.6 mg/L
- China: GB 5749-2022 sets 0.3-4 mg/L range for potable water
- India: IS 10500:2012, permissible 0.2 mg/L residual at consumer end
7. FAQ
Q: Can I use TCCA for drinking water?
A: Not recommended. TCCA is acidic (pH 2.7-3.5) and slow-dissolving; the 30-min contact requirement cannot be met reliably with tablets.
Q: What if water tastes like chlorine?
A: Either overdose (test residual — should be < 1 mg/L) or Cl reacting with organics. Filter through activated carbon before consumption.
Q: Can I bulk-dose 1000 liters with 1 SDIC 25kg drum?
A: No. Use ~2g per 1000L for 1 mg/L residual. 25kg drum treats 12,500,000 liters at that rate.
Q: What is the shelf life of SDIC tablets?
A: 3 years sealed. Loss of active chlorine ~1% per year in cool dry storage.
Bulk SDIC for Water Projects
Shilan Chemical supplies NGOs, disaster relief organizations, and municipal water authorities with NSF-compliant SDIC 60%. Volume discounts, WHO-labeled packaging available, and shipping to 45+ countries. Get project quote →