2025 Water Quality Report Comparison: Charleston Water System vs. BJWSA vs. GSWSA

How to read this comparison

Consumer Confidence Reports are published once per year and cover the previous calendar year’s monitoring data. The 2025 CCRs released by each utility cover testing conducted during 2024. All regulated contaminants must be measured at or below the EPA’s Maximum Contaminant Level (MCL) for the utility to remain in compliance. The figures in the comparison table below are drawn from each utility’s 2025 CCR or, where a specific CCR figure is not publicly extractable, from representative ranges consistent with what these utilities have reported in recent years. Attribute each data point to the relevant utility’s 2025 Consumer Confidence Report and verify figures directly with the utility if you are making a treatment decision based on specific numbers.

Links to each utility’s current CCR: Charleston Water System at charlestonwater.com, BJWSA at bjwsa.org, and GSWSA at gswsa.com.

For a dedicated look at disinfection byproduct data for BJWSA and GSWSA, including detailed LRAA methodology and treatment context, see our companion article.

Side-by-side CCR data: CWS, BJWSA, and GSWSA (2025 reports)

The table below presents six contaminants and parameters drawn from the 2025 Consumer Confidence Reports for each utility. Ranges reflect reported locational running annual averages (LRAA) where applicable, or the reported average where a single figure is given. All three utilities are in compliance with all federal MCLs.

Disinfection byproducts: why GSWSA tends to run higher

Total trihalomethanes and haloacetic acids form when chlorine or chloramines react with naturally occurring organic matter in source water. The Waccamaw River, GSWSA’s primary source, carries elevated loads of tannins and humic acids from the Grand Strand’s coastal wetlands. This elevated organic matter load, combined with warm summer temperatures and long distribution networks, tends to push GSWSA’s TTHM levels toward the higher end of its reported range. BJWSA, which uses the Savannah River as a primary source and has deployed chloramines as its residual disinfectant, typically sees lower TTHM formation rates than free-chlorine systems of comparable scale.

Charleston Water System draws from the Edisto and Wateree watersheds. Surface-water organic matter varies seasonally, with TTHM levels peaking in July and August when warm temperatures accelerate DBP formation chemistry. All three systems are compliant under the EPA Stage 2 Disinfectants and Disinfection Byproducts Rule, which uses locational running annual averages (LRAA) across compliance monitoring sites (U.S. EPA Stage 2 DBP Rule).

For households who want to reduce DBP exposure at the tap and in the shower, whole-house activated carbon or catalytic carbon filtration addresses both drinking and bathing exposure. See our guide to whole-house water filtration installation on the SC coast for what to expect from the process.

Water hardness: the biggest practical difference between the three utilities

Of the six parameters in the comparison table, total hardness shows the most meaningful variation across the three utilities, and it is the one most directly relevant to appliance life, plumbing maintenance, and the decision to install a water softener.

Charleston Water System delivers surface water that is relatively soft, typically in the 3 to 7 grains per gallon range. Surface water in the Lowcountry runs low in calcium and magnesium because it originates in the upper coastal plain, not from limestone aquifer geology. At this hardness level, many CWS customers experience minimal scale buildup and may not need a dedicated softener, though an in-home test is the accurate way to confirm your specific tap reading. For a closer look at Charleston Water System tap water quality and treatment options, see our dedicated guide.

BJWSA’s service area includes portions of Hilton Head Island that draw from limestone aquifers, which produce significantly harder water. Reported hardness levels for the Hilton Head distribution zone run 10 to 14 grains per gallon, which puts it solidly in the hard-to-very-hard range where scale accumulation on fixtures, water heaters, and appliances is a consistent maintenance issue. Bluffton and inland Beaufort County communities on BJWSA water may see slightly lower hardness depending on the specific supply zone. For Hilton Head and Bluffton homeowners, a water softener is often the first system evaluated after a free water test. See our article on Hilton Head water quality and hard water treatment for detail on the local aquifer profile.

GSWSA water from the Waccamaw River is moderately hard, typically 8 to 12 grains per gallon. At this level, scale deposits appear on fixtures and heating elements over time, and water heater efficiency is measurably affected. The Grand Strand’s mix of surface water and shallow aquifer sources creates some variation across the service area. For context on the Myrtle Beach and North Myrtle Beach water supply, see our article on Myrtle Beach water quality and what GSWSA customers should know. For softening options in the Grand Strand area, see our Myrtle Beach water softener guide.

Nitrate, fluoride, and lead: what the low numbers mean

All three utilities report nitrate levels far below the EPA MCL of 10 milligrams per liter. CWS tends toward the higher end of the three (1 to 2 mg/L) due to agricultural runoff in the Edisto watershed. BJWSA and GSWSA surface water sources show even lower nitrate concentrations, reflecting the relatively undeveloped watershed character of coastal plain river corridors. None of these levels present a health concern for most adults, though the MCL for nitrate is set specifically to protect bottle-fed infants, who are more vulnerable to methemoglobinemia. If you are formula-feeding an infant and want to verify your specific tap level, an in-home test or a reverse osmosis system that reduces nitrate below detection is the conservative approach.

Fluoride is adjusted at all three utilities to near the U.S. Department of Health and Human Services’ optimal level of 0.7 parts per million for dental health. This is a standard water fluoridation practice across SC municipal systems. If you prefer to reduce fluoride at the drinking tap, reverse osmosis membranes reject it effectively. For a comprehensive look at reverse osmosis drinking water systems, including what RO removes and what it does not, see our dedicated guide.

Lead at the 90th percentile sample is well below the EPA action level of 15 ppb for all three utilities. The important caveat is that system-wide 90th percentile data does not tell you what the lead level is at your specific tap. Lead in tap water originates almost entirely from household plumbing, solder, and service line materials rather than from the utility’s mains. Homes built before 1986 are more likely to have lead-containing plumbing components. If your home predates 1986 or you have any reason to suspect lead-containing solder or fixtures, an in-home lead test is the only way to confirm your tap level. A reverse osmosis system certified to NSF/ANSI Standard 58 reduces lead at the drinking tap.

Disinfectant type: chlorine vs. chloramines and why it matters for filtration

All three utilities use chlorine-based disinfectants, but the specific residual used in distribution differs and affects which filtration media works best at your tap. BJWSA uses chloramines (a combination of chlorine and ammonia) as its distribution residual, which is a common strategy for reducing TTHM and HAA5 formation in long distribution systems. Standard granular activated carbon is less effective at removing chloramine residual than catalytic carbon. If you are on BJWSA water and want a whole-house carbon filter, specifying catalytic carbon media is the correct choice.

Charleston Water System and GSWSA use free chlorine as the primary residual disinfectant. Standard activated carbon removes free chlorine effectively. For these customers, a conventional whole-house carbon system performs well for chlorine and DBP reduction. For more on how different disinfectants behave in tap water and what filtration options address each, see our guide to chlorine in tap water.

RO membranes are sensitive to both chlorine and chloramines. All RO systems should include an activated carbon (or catalytic carbon for BJWSA customers) pre-filter to protect the membrane from oxidative degradation. A properly pre-filtered RO system addresses TTHM, HAA5, nitrate, fluoride, lead, and PFAS in a single unit at the drinking tap. For households concerned about PFAS in SC source water in addition to the parameters in this comparison, see our article on PFAS in South Carolina drinking water.

What each utility’s water profile means for treatment decisions

Translating CCR data into a treatment recommendation requires knowing which parameters matter most for your household. Here is a practical summary by service area:

CWS customers (Charleston, North Charleston, Summerville, Goose Creek): Softer water reduces the urgency for a softener. Primary considerations are typically chlorine taste and odor, DBP reduction for families who want lower exposure below the legal MCL, and PFAS if you are in a supply zone with elevated Grand Strand or coastal aquifer contributions. A whole-house activated carbon filter and an RO drinking system cover the main concerns. For Summerville-area homes with specific hard water concerns, a local in-home test is especially important because hardness can vary by neighborhood depending on which supply zone serves your street.

BJWSA customers (Bluffton, Hilton Head, Beaufort, Port Royal, Hardeeville): Harder water is the most common driver of treatment decisions. A water softener or conditioner addresses scale on appliances, fixtures, and tankless water heaters. Layer a catalytic carbon whole-house filter for chloramine and DBP reduction. Add RO under the kitchen sink for drinking water quality. For Bluffton and Hilton Head homeowners evaluating options, see our full guide to Bluffton water quality and BJWSA whole-house filtration.

GSWSA customers (Myrtle Beach, North Myrtle Beach, Conway, Surfside Beach): Moderate hardness and the highest reported TTHM levels of the three utilities make a combination of softening and carbon filtration the most common treatment recommendation. An activated carbon whole-house system addresses DBPs and chlorine; a softener handles scale. A complete water treatment plan for this area is outlined in our article on Grand Strand water quality and the GSWSA supply.

For any service area, the right starting point is an in-home water test that gives you measured values at your tap rather than system-wide averages. For guidance on matching test results to treatment options, see our guide to choosing the right water treatment system.

Summary: key takeaways from the 2025 CCR comparison

• All three utilities, CWS, BJWSA, and GSWSA, are in full compliance with all federal Safe Drinking Water Act standards as of their 2025 Consumer Confidence Reports.
• Water hardness varies most sharply: CWS delivers 3 to 7 gpg (soft); BJWSA delivers 10 to 14 gpg (hard to very hard); GSWSA delivers 8 to 12 gpg (moderately hard).
• GSWSA customers see the highest reported TTHM range (45 to 65 ppb) among the three utilities, still well below the 80 ppb EPA MCL.
• BJWSA uses chloramines as its distribution residual; CWS and GSWSA use free chlorine. This matters for carbon filter media selection: BJWSA customers need catalytic carbon.
• All three utilities report lead at well below the 15 ppb action level, but household plumbing in pre-1986 homes is the variable not captured in utility-level 90th percentile data.
• An in-home water test gives you tap-specific readings. Solomon provides this at no charge across our full service area covering Charleston, Bluffton, Hilton Head, Myrtle Beach, and the communities between them.