| Sodium dichloroisocyanurate (NaDCC) | Portable or emergency drinking-water treatment when the specific product is labeled for potable water; also used in some sanitation applications. | Releases available chlorine in water. Chlorine performance depends on dose, contact time, water temperature, pH, and turbidity. Chlorine is not reliably effective against all protozoan cysts, particularly Cryptosporidium. | Oxidizing chemical. Avoid ingestion of dry tablets, inhalation of dust, and contact with eyes or skin. Never mix with acids or ammonia-containing products. | Chlorine can react with natural organic matter and form disinfection by-products. Use only the labeled dose and avoid unnecessary over-treatment. | Confirm potable-water labeling, dose per volume, required contact time, residual-chlorine instructions, storage conditions, and local regulatory acceptance. |
| Chlorine dioxide tablet system | Water treatment where the product is specifically formulated and labeled for the intended potable-water or sanitation use. Some systems require an activator or a separate component. | Can inactivate a range of microorganisms under validated conditions. Actual effectiveness depends on formulation, preparation, dose, contact time, and water quality; do not assume all tablets have the same performance. | Follow preparation and ventilation instructions carefully. Do not combine components except as directed. Observe stated waiting times and any restrictions on treated water. | Chlorine dioxide use can produce chlorite and chlorate residuals. Applicable limits and monitoring requirements vary by jurisdiction and application. | Check whether activation is required, preparation steps, validated organism claims, residual limits, shelf life, and documentation for the destination market. |
| Iodine-based tablets | Some emergency or backcountry water-treatment products, subject to product labeling and local guidance. | Can disinfect water when used as directed, but performance varies with water conditions and contact time. Iodine is not reliably effective against Cryptosporidium. | Not suitable for everyone or for unrestricted long-term use. People with thyroid conditions, iodine sensitivity, or pregnancy-related concerns should seek medical guidance before use. | Iodine may leave taste or color and can contribute to iodine exposure. Follow disposal instructions and avoid unnecessary release to the environment. | Verify potable-water approval, user warnings, treatment limitations, taste considerations, expiry date, and whether use is restricted by local health guidance. |
| Bromine-based tablets | Most commonly used for swimming pools and spas; generally not a drinking-water treatment option. | Provides a bromine-based disinfectant residual in appropriately managed pool or spa water. Performance depends on maintaining the specified operating conditions and water balance. | Concentrated tablets can cause burns and eye injury. Keep dry, prevent contamination, and never mix with other pool chemicals. | Discharge restrictions may apply to treated pool or spa water. Follow local rules and product directions for draining or disposal. | Confirm the intended application, permitted use, required feeder or dosing method, water-testing routine, and wastewater-disposal rules. |