Most Central Florida homeowners assume drinking water is "chlorinated" and leave it at that. But the three biggest utilities in the Orlando metro, OUC, Toho Water Authority, and Orange County Utilities, use three different disinfection approaches, and the difference directly determines whether your home carbon filter is doing its job or quietly letting disinfection residuals through.
The Three Disinfection Approaches
OUC, Ozone Primary + Chlorine Residual
Orlando Utilities Commission uses ozone (O₃) as its primary disinfectant, with free chlorine added only to maintain a residual in the distribution system. Ozone is an exceptionally powerful oxidizer, more effective than either chlorine or chloramines against pathogens, and it also removes hydrogen sulfide (the rotten-egg odor naturally present in Floridan Aquifer water). Because ozone decomposes rapidly back into oxygen, it leaves no persistent residual of its own; that's why OUC still adds chlorine at the end of treatment.
For OUC customers, the water reaching your tap carries a free chlorine residual, not chloramines. This matters because free chlorine is easy to remove with standard activated carbon filtration at residential flow rates.
Toho Water Authority, Chloramines
Toho Water Authority, which serves more than 100,000 customers in Kissimmee, Poinciana, and unincorporated Osceola County, uses chloramines, a combination of chlorine and ammonia. Chloramines persist longer in distribution pipes and produce fewer trihalomethanes (regulated carcinogenic byproducts) than free chlorine. Toho does run occasional temporary free-chlorine conversions for specific areas; a notice in March 2026 alerted Harmony-area customers to a 5–7 day switch for maintenance purposes.
For Toho customers, the water reaching your tap carries a chloramine residual, which is fundamentally harder to remove with standard carbon.
Orange County Utilities, Likely Free Chlorine
Orange County Utilities, separate from OUC, serves unincorporated Orange County. OCU typically uses free chlorine, though you should verify against the current Annual Drinking Water Report (CCR) for your specific service area before assuming.
Typical Residual Levels
EPA sets a Maximum Residual Disinfectant Level (MRDL) of 4.0 ppm for both chlorine and chloramines in finished drinking water. Central Florida utilities typically run:
- Chloramine residual (Toho): 1.5–3.5 ppm
- Free chlorine residual (OUC, OCU): 1.0–2.5 ppm at the plant, lower at distant distribution points
Why the Distinction Matters for Home Filtration
Standard granular activated carbon (GAC) removes free chlorine through a fast surface reaction, water contacts carbon, chlorine is reduced to chloride, and filtered water exits. Typical residential GAC removes 90%+ of chlorine at normal flow rates.
Chloramines don't work that way. The N-Cl bond in monochloramine (NH₂Cl) is far more stable, and removing it requires chemical decomposition rather than simple adsorption. Published performance data:
- Standard GAC on chloramine: 40–65% removal at residential flow, much lower than chlorine removal, and it drops further as the carbon ages.
- Catalytic carbon on chloramine: 90%+ removal. The media surface is specifically treated to catalyze the chloramine decomposition reaction.
If you're a Toho Water customer and you bought a "chlorine taste and odor" filter, you're probably getting significantly less chloramine removal than you think. After 6–12 months of use, most standard GAC units are pass-through for chloramine.
Practical Selection Guide
OUC customer: Standard GAC whole-house filter works for chlorine. Consider an under-sink RO for drinking water quality (DBPs, trace contaminants). The ozone upstream means your water already has lower H₂S and lower overall organic loading.
Toho Water customer: You specifically need catalytic carbon media, not standard GAC, for whole-house chloramine removal. NSF/ANSI 42 certified for chloramine reduction is the standard. An under-sink RO adds a second barrier for drinking water.
Orange County Utilities customer: Likely same approach as OUC (free chlorine removable with standard GAC) but verify your CCR. OCU has a separate PFAS situation, two facilities detected at or above the 4 ppt MCL (Malcolm Road ~4.7 ppt; County Road 535 ~5 ppt), so under-sink RO is worth serious consideration for drinking water.
How to Verify Your Disinfectant
Three ways:
- Your utility's CCR. The annual Consumer Confidence Report identifies the primary disinfectant. Published by July 1 each year.
- Simple home test strips. Total chlorine vs. free chlorine strips are cheap. If total chlorine is significantly higher than free chlorine, you have chloramines (the difference is combined chlorine = chloramines).
- Ask a water professional. Pure Agua tests chloramine specifically during free water testing.
Aquarium and Pond Owners
Chloramines are acutely toxic to fish at Toho residual levels. Unlike free chlorine, chloramines do not off-gas from standing water within hours, they persist for days. Dechlorination conditioners specifically formulated for chloramines (not just chlorine) are required for every water change.
OUC's ozone-primary approach doesn't reach aquariums, by the time water reaches your tap, you're dealing with the free chlorine residual added at the end of treatment. Standard aquarium conditioners handle this fine.
Get Your Water Tested
Pure Agua provides free in-home water testing throughout Osceola, Orange, and Seminole Counties, we measure your exact chloramine or chlorine residual, hardness, pH, and TDS, and we know the differences between Toho Water, OUC, and OCU service areas. 5.0★ rated with 200+ Google reviews. Family-owned since 2016.
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