Is Corona tap water safe to drink?

Corona, City of disinfects with chloramine, based on its treatment records filed with EPA. Chloramine is chlorine bonded with ammonia. It lasts longer in the pipes, which is why utilities use it, but it is much harder to remove at home than plain chlorine. Treatment records can lag changes, so confirm it in your utility's annual water quality report.

Most cheap shower filters use KDF and standard carbon, which barely affect chloramine. Look for vitamin C or catalytic carbon media, and for drinking water, a filter that lists chloramine reduction specifically. If you keep fish, chloramine must be neutralized before it reaches the tank.

Corona's water measures about 9.0 grains per gallon (154 mg/L as calcium carbonate), which is hard on the US Geological Survey scale: soft below 60 mg/L, moderately hard 60-120, hard 120-180, very hard above 180.

Hard water is not a health risk, but it is expensive. It leaves scale in water heaters, dishwashers and fixtures, spots glassware, and makes soap lather poorly. Only an ion-exchange softener removes the minerals. Filters, including shower filters, do not soften water, whatever the packaging implies. A salt-free scale conditioner reduces scale buildup without removing minerals, and needs no drain line.

Hardness data: TapWaterData Water Hardness Dataset (tapwaterdata.com), licensed CC BY 4.0. Underlying source: Utility-reported water quality data — CORONA, CITY OF (PWSID CA3310037), 2025-09-22.

In Corona, City of's most recent lead sampling, for the period ending December 2023, 90% of tested homes came in at or below 3.7 ppb of lead. That is low on any of the federal yardsticks. The copper result for the same period was 1.77 mg/L (action level 1.3).

This is a system-wide statistic, not a reading of your tap. Lead comes from lead service lines, old solder and some brass fixtures inside homes, so two houses on the same street can differ. Testing your own tap costs $15-40, and many utilities test free on request.

EPA's lead action level is 15 parts per billion (ppb) today and drops to 10 ppb in November 2027 under the Lead and Copper Rule Improvements. FDA's limit for bottled water is 5 ppb. EPA's health goal for lead is zero.

In EPA's 2023-2025 sampling of Corona, City of, these PFAS were detected: PFHxS up to 3.3 ppt (2024 limit 10). All results were below the 2024 limits. These are the highest single results; utilities are judged on running annual averages, so a high sample is not by itself a violation.

Reverse osmosis is the most reliable home treatment for PFAS. Some carbon filters are certified for PFOA and PFOS reduction under NSF/ANSI 53; check the product listing for that claim, not just the word PFAS on the box.

In April 2024 EPA set enforceable limits of 4 parts per trillion (ppt) for PFOA and PFOS, and 10 ppt for PFHxS, PFNA and HFPO-DA (GenX). In May 2025 EPA said it intends to keep the PFOA and PFOS limits, extend the compliance deadline to 2031, and rescind the other three. We compare results to the 2024 limits and label which ones may change.

Corona, City of has no health-based violations on file with EPA since 2016.

Corona is in Riverside County, which EPA places in Radon Zone 2: the predicted average indoor level is between 2 and 4 pCi/L.

Zone describes a county average. Individual homes in every zone test high, so EPA recommends testing every home, especially basements and ground floors. Fix at 4 pCi/L or above.

EPA radon zones describe counties, not houses. Zone 1 counties have a predicted average indoor level above 4 picocuries per liter (pCi/L), Zone 2 between 2 and 4, Zone 3 below 2. Homes with high levels are found in every zone, which is why EPA recommends that every home be tested, and fixed at 4 pCi/L or above. See every California county's radon zone.