Water · Water Treatment
Two components, one reaction, one disinfectant. The chemistry is what matters — and not all two-part kits use the same chemistry.
The basics
Two-part water treatment kits separate components that would degrade or react prematurely if stored together. When you mix Part A and Part B, a chemical reaction produces the active disinfectant. The disinfectant cannot be stored pre-mixed — it must be generated fresh at the point of use.
In chlorine dioxide kits like Aquamira, Part A contains sodium chlorite and Part B contains citric acid or phosphoric acid. When mixed, they generate chlorine dioxide gas in solution. Chlorine dioxide is a stronger oxidant than chlorine, covers a broader spectrum of pathogens, and does not produce the taste or discoloration of iodine-based alternatives.
In older iodine-based two-part kits, Part A is typically iodine and Part B is an ascorbic acid neutralizer that improves taste after treatment. The mixing sequence is different: you treat with Part A first, wait, then add Part B. These kits are still sold but have been largely displaced by chlorine dioxide options, which have better pathogen coverage and no medical contraindications.
Understanding which chemistry a kit uses is not a minor detail. It determines what the kit can and cannot kill. Two kits packaged identically may have completely different coverage depending on whether the active ingredient is chlorine dioxide or iodine.
Quantity guidance
Kit capacity depends on the product. Aquamira 1-ounce kits treat up to 30 gallons; 2-ounce kits treat up to 60 gallons. One kit per person is adequate for a 72-hour to 2-week emergency. For households relying on drops as a primary treatment, stock two kits per person as a baseline.
| Scenario | Per person | Family of 4 |
|---|---|---|
| 72-hour kit | 1 oz kit (30 gal) | 1 oz kit covers all 4 |
| 2-week supply | 1 oz kit sufficient | 1–2 oz kit |
| Recommended baseline | 1 oz in bag, 2 oz at home | 2–3 oz total |
Storage
For chlorine dioxide two-part kits, store Part A and Part B separately. The components are shelf-stable when kept apart — Aquamira has a 4-year shelf life from manufacture for both components. Do not combine them in advance. Once mixed, the activated solution should be added to water immediately.
Part A (sodium chlorite) is the more sensitive component. Exposure to light, heat, or air accelerates its oxidation. Store it in the original opaque bottle in a cool, dark location. If the Part A solution has changed from clear or slightly yellow to a darker color, the component may have degraded.
Once a kit is opened, use within one year. Mark the opening date on each bottle. Carry kits in a small zipper bag inside your go-bag to prevent leaks from affecting other contents.
Chemistry comparison
The two-part format is a packaging method, not a specific chemistry. Always check the active ingredient before buying. These are the two formats you will encounter.
Part A: sodium chlorite. Part B: citric acid. Mix generates chlorine dioxide in solution.
NWS pick — buy this format
Part A: iodine tablets. Part B: ascorbic acid tablets (taste neutralizer). Treat with A, wait, then add B.
Lower coverage — only if ClO2 unavailable
NWS recommendation: Buy chlorine dioxide two-part kits — specifically Aquamira — over iodine-based formats. The coverage is broader, the taste is better, and there are no medical restrictions. The only reason to use iodine is if chlorine dioxide is genuinely unavailable. The two-part packaging of the iodine format does not improve its chemistry limitations.
Safety & dosing
For chlorine dioxide two-part kits (Aquamira): mix 7 drops Part A + 7 drops Part B in the provided mixing cap. Wait 5 minutes. The solution must turn bright yellow before you add it to water. If it does not turn yellow, the kit is expired or degraded. Add the activated solution to 1 liter of water. Wait 30 minutes for bacteria, viruses, and Giardia. Wait 4 hours for full Cryptosporidium coverage.
For iodine two-part kits: add the iodine tablet (Part A) to 1 liter of water, wait 30 minutes, then add the taste-neutralizing tablet (Part B) and wait 3 more minutes before drinking. Do not add Part B before the iodine contact time is complete.
Pre-filter turbid water before treating with any chemical kit. Particles in the water shield pathogens and reduce treatment effectiveness. Settle, decant, or filter through a cloth before applying chemical treatment.
Iodine restriction reminder: Per CDC guidance, iodine-treated water is not recommended for pregnant women, people with thyroid conditions, or anyone with iodine hypersensitivity. If your household includes any of these individuals, use chlorine dioxide kits only.
Per Aquamira product label; CDC emergency water guidance (CDC: Water in an Emergency). Verified June 2026.
Where to buy
Top pick
Two-part chlorine dioxide, liquid
The benchmark two-part chlorine dioxide kit. EPA-registered (No. 71766-1). Treats 30 gallons (1 oz) or 60 gallons (2 oz). Full pathogen coverage including Crypto with 4-hour contact. No medical restrictions. Made in the USA.
$12 – $18 per kit
View on AmazonTablet alternative
Chlorine dioxide tablets — simpler for field use
Pre-measured chlorine dioxide tablets. Same chemistry as Aquamira without the mixing step. One tablet per liter. Better choice for go-bags where simplicity matters. Less economical per gallon than drops.
$12 – $18 per 30-count pack
View on AmazonAffiliate disclosure: New World Survival earns a small commission on purchases made through links on this page, at no cost to you. We only recommend products we would stock in our own kit.
Related
Two-part kits work alongside mechanical filtration and stored water. The pages below connect to the full system.