Franklin · Williamson County · 2026 EWG Data · 5 Utilities
Franklin, TN Water Quality Guide 2026
What's actually in your Franklin tap water — verified data from EWG's database for all five Williamson County utilities. Up to 100x above health guidelines for disinfection byproducts. Plus a Franklin-specific concern you won't see on most water guides: chlorate at 5x the state average.
Updated June 2026 Sources: EWG Tap Water Database (2013–2024) · Franklin Water Management Dept. Independent — Tennessee Water Authority
Contaminant data sourced from EWG's Tap Water Database (testing 2013–2024) and 2025/2026 official Consumer Confidence Reports: H.B.&T.S. 2026 CCR, HVUD 2026 CCR (HVUD-26), and Mallory Valley 2026 CCR. All five Franklin-area utilities were in full compliance with all EPA federal drinking water standards as of June 2024.
Downtown Franklin, TennesseeWilliamson County's fastest-growing city
Legal limits ≠ optimal health. Every contaminant on this page is within EPA legal limits. "Exceeds EWG guideline" means detection above EWG's more conservative health thresholds — not a regulatory violation. Franklin's water is safe by federal standards. This guide helps you understand the gap and decide whether additional filtration makes sense for your household.
Your Five Franklin, TN Utilities at a Glance
Franklin is served by more utilities than almost any other Middle Tennessee city. Five separate systems serve different parts of Franklin and Williamson County. Four of them purchase treated water from Harpeth Valley Utility District, which draws from the Cumberland River. Only Franklin Water Department treats its own Harpeth River source water directly. All share similar disinfection byproduct profiles because chlorination of surface water produces the same byproducts regardless of the specific river.
Four of the five Franklin-area utilities — HVUD, H.B.&T.S., Mallory Valley, and Milcrofton — purchase treated water from Harpeth Valley Utility District, which draws from the Cumberland River (Cheatham Lake) in Nashville. Franklin Water Department is the exception: it operates its own treatment plant on the Harpeth River and supplements with purchased HVUD water. Because four utilities share the same Cumberland River source water, their disinfection byproduct profiles are nearly identical — TTHMs, HAAs, and chloroform appear across all systems for the same reason: chlorine reacting with organic matter during treatment.
Utility
Source water
Treatment
Franklin Water Dept.
Harpeth River (direct) & Cumberland River via HVUD
Own treatment plant on the Harpeth River
H.B. & T.S. UD
Cumberland River / Cheatham Lake
Purchased from HVUD — treated at HVUD plant
Milcrofton UD
Cumberland River / Cheatham Lake
Purchased from HVUD — 20-mile underground pipeline from Nashville
HVUD
Cumberland River / Cheatham Lake
HVUD own treatment plant — wholesale supplier to H.B.&T.S. & Milcrofton
Mallory Valley UD
Cumberland River / Cheatham Lake
Purchased from HVUD
241K+
Williamson County residents served across all five utilities
11
Max contaminants above EWG guidelines (Mallory Valley)
100x
Bromodichloromethane above EWG guideline in Franklin Water Dept.
5×
Franklin chlorate above Tennessee state average — unique concern
Contaminants Exceeding EWG Health Guidelines
Each card below shows detected levels across all five utilities where data is available. All are within EPA legal limits. The "Nx" figure shows how many times above EWG's health guideline the contaminant was found.
Disinfection Byproducts — Primary concern from surface water chlorination (Cumberland River / Harpeth River)
Bromodichloromethane
Disinfection Byproduct (TTHM)
100x
FWD above EWG · 118x H.B.T.S.
Franklin WD
6.01 ppb
EWG: 0.06 ppb
H.B.&T.S.
7.08 ppb
118x EWG
Harpeth Valley
5.97 ppb
~100x EWG
Mallory Valley
Detected above EWG
similar profile
Milcrofton
Detected above EWG
similar profile
Health concern: Cancer risk and harm to fetal development. One of four TTHMs formed when chlorine reacts with organic matter in the Harpeth River source water. H.B.&T.S.'s level (7.08 ppb) exceeds the national average (5.89 ppb). Franklin Water Dept. (6.01 ppb) is essentially at the national average — but both are 100x above EWG's 0.06 ppb health guideline.
Chloroform
Disinfection Byproduct (TTHM)
91x
FWD above EWG — 2x state avg
Franklin WD
36.4 ppb
EWG: 0.4 ppb · 91x
H.B.&T.S.
30.6 ppb
77x EWG
Harpeth Valley
~35+ ppb
similar to FWD
Mallory Valley
Detected above EWG
—
Milcrofton
Detected above EWG
—
Health concern: Cancer risk, reproductive harm. Franklin Water Dept.'s chloroform level (36.4 ppb) is more than double both the Tennessee state average (17.7 ppb) and national average (16.2 ppb). This is the single most elevated contaminant relative to peer utilities in Middle Tennessee and warrants activated carbon whole-house filtration for Franklin homes.
Dibromochloromethane
Disinfection Byproduct (TTHM)
43x
FWD · 17x H.B.T.S. above EWG
Franklin WD
~4.3 ppb
EWG: 0.1 ppb · 43x
H.B.&T.S.
1.72 ppb
17x EWG
Harpeth Valley
Detected above EWG
—
Mallory Valley
Detected above EWG
—
Milcrofton
Detected above EWG
—
Health concern: Cancer risk and potential harm during pregnancy. Third member of the TTHM family present across all Franklin utilities. Removed effectively by activated carbon and reverse osmosis.
Haloacetic Acids (HAA5 / HAA9)
Disinfection Byproduct Group
400x+
Hundreds of times above EWG guideline
Franklin WD
HAA5 detected above EWG
EWG: 0.1 ppb
H.B.&T.S.
HAA5 detected above EWG
—
Harpeth Valley
HAA5/9 above EWG
—
Mallory Valley
HAA5/9 above EWG
—
Milcrofton
HAA5 above EWG
—
Health concern: Long-term cancer risk. HAAs are the second major group of disinfection byproducts, formed alongside TTHMs in all chlorinated surface water systems. EWG's guideline (0.1 ppb for HAA5) is far more stringent than the EPA legal limit (60 ppb). All five Franklin utilities are within EPA limits. The "hundreds of times" figure reflects the EWG guideline gap, not an emergency.
PFOS 0.0013 ppt · PFBS 0.0014 ppt · far below EPA MCL of 4 ppt
Milcrofton
2025 data pending
purchases from HVUD — same source chain
Important 2025 update from official CCRs: The most recent Consumer Confidence Reports for H.B.&T.S., Harpeth Valley Utility District, and Mallory Valley all show no meaningful PFAS detections in 2025. HVUD's 2025 report (HVUD-26) confirms zero detections for all six regulated PFAS compounds. Mallory Valley's 2025 CCR shows only trace PFOS (0.0013 ppt) and PFBS (0.0014 ppt) — both over 1,000x below EPA's new 4 ppt MCL. The EWG database reflects historical 2013–2024 testing. Franklin Water Department's PFOA detection remains based on historical EWG data — verify with the Franklin WD 2025 CCR directly for the current status. PFAS levels in the broader Franklin area appear to have improved significantly based on the most recent utility reporting.
Industrial & Chemical Contaminants
Chromium (Hexavalent / Cr-6)
Industrial / Naturally Occurring
4.5x
FWD · 4.3x H.B.T.S. above EWG
Franklin WD
0.090 ppb
EWG: 0.02 ppb · 4.5x
H.B.&T.S.
0.0855 ppb
4.3x EWG
Harpeth Valley
Detected above EWG
—
Mallory Valley
Detected above EWG
—
Milcrofton
Detected above EWG
—
Health concern: Known human carcinogen. Both Franklin Water Dept. and H.B.&T.S. are below the Tennessee state average (0.102 ppb) for chromium-6. No federal MCL exists specifically for hexavalent chromium. Reverse osmosis is the most effective removal method; anion exchange also works. Standard activated carbon provides minimal reduction.
Agricultural Contaminants
Nitrate
Agricultural Runoff
6x
FWD above EWG · within EPA limit
Franklin WD
~0.84 ppm
EWG: 0.14 ppm · ~6x
H.B.&T.S.
Within EWG guideline
—
Harpeth Valley
Detected above EWG
—
Mallory Valley
Detected above EWG
—
Milcrofton
Within EWG guideline
—
Health concern: Cancer risk at chronic low-level exposure (EWG concern). Acute infant risk above 10 ppm — all Franklin utilities are well below that threshold. Nitrate comes from agricultural fertilizer runoff in the Harpeth watershed from Williamson County's farmland. Carbon filters do NOT remove nitrate. Reverse osmosis is required.
The Franklin-Specific Concern: Chlorate
Chlorate is present in all Franklin-area water, but Franklin Water Department's level is a standout that most water guides miss entirely — it's 5x above Tennessee's state average and nearly 6x the national average. This is worth understanding separately.
Chlorate: The thyroid contaminant Franklin homeowners should know about
Franklin Water Department detected chlorate at 591.3 ppb — 2.8x EWG's health guideline of 210 ppb. More significantly, this is 5x the Tennessee state average (99.1 ppb) and 5x the national average (116.8 ppb). Chlorate forms when chlorine-based disinfectants (like sodium hypochlorite) react during treatment. It impairs thyroid function by blocking iodine uptake — making it particularly concerning during pregnancy and childhood. No EPA legal limit currently exists for chlorate; EWG's 210 ppb guideline is based on EPA benchmark testing. Reverse osmosis significantly reduces chlorate; activated carbon also provides reduction.
Chlorate
Disinfection Byproduct / Industrial
2.8x
FWD — 5x Tennessee state average
Franklin WD
591.3 ppb
EWG: 210 ppb · 2.8x
Source: Agriculture, industry, and treatment byproducts. Chlorate forms when sodium hypochlorite (liquid bleach used in water treatment) degrades or reacts. Franklin WD's level is significantly elevated compared to peer systems across Tennessee. Families with pregnant members or young children served by Franklin Water Department should consider reverse osmosis for drinking and cooking water as a precautionary measure.
All Five Utilities — Side-by-Side Comparison
Key contaminant levels across all five Franklin-area utilities. Check your water bill or call your utility if you're unsure which system serves your address.
Contaminant
EWG Guideline
Franklin WD TN0000246
H.B.&T.S. TN0000699
Harpeth Valley TN0000286
Mallory Valley TN0000428
Milcrofton TN0000247
Bromodichloromethane
0.06 ppb
6.01 ppb · 100x
7.08 ppb · 118x
5.97 ppb · ~100x
Above EWG
Above EWG
Chloroform
0.4 ppb
36.4 ppb · 91x
30.6 ppb · 77x
~35 ppb · ~87x
Above EWG
Above EWG
Chlorate
210 ppb
591 ppb · 2.8x
No EWG data
No EWG data
No EWG data
No EWG data
Chromium (Hex)
0.02 ppb
0.090 ppb · 4.5x
0.086 ppb · 4.3x
Above EWG
Above EWG
Above EWG
Nitrate
0.14 ppm
~0.84 ppm · ~6x
Within guideline
Above EWG
Above EWG
Within guideline
PFOA / PFAS
0.09 ppt
Above EWG (historical)
No detection 2025
No detection 2025
Trace only · below EPA MCL
2025 data pending
HAA5 / HAA9
0.1 / 0.06 ppb
Hundreds × EWG
Above EWG
Above EWG
Above EWG
Above EWG
Total TTHMs
0.15 ppb
~44 ppb avg · 250x+ EWG
56 ppb avg (38–63) · 373x
40.1 ppb avg (20.8–48.6) · 267x
38.73 ppb avg (27–57) · 258x
Similar profile · 200x+ EWG
Contaminants above EWG
—
10 of 17
9 of 13
10 of 16
11 of 19
9 of 14
What "200x+ EWG" actually means: EWG's guideline for TTHMs (0.15 ppb) is set at a 1-in-1,000,000 lifetime cancer risk level based on California OEHHA standards. The EPA legal limit is 80 ppb. Saying water contains TTHMs "200x above EWG guidelines" is accurate — but it does not mean the water is acutely dangerous. Both figures are expressing the same measurement against very different standards. Your Franklin water is legal and compliant. The question is whether you want to optimize beyond legal compliance.
Williamson County Limestone Hard Water
Four Franklin-area utilities purchase treated water from Harpeth Valley Utility District, which draws from the Cumberland River (Cheatham Lake). The 2025 CCRs for H.B.&T.S., HVUD, and Mallory Valley all report a hardness average of 135 PPM (7.9 GPG) — classified as moderately hard. Franklin Water Department treats the Harpeth River directly and may show slightly different hardness. Wells in Williamson County's limestone geology are substantially harder.
At 7.9 GPG, scale buildup is significant — particularly on tankless water heater heat exchangers operating above 120°F. The 2025 CCRs confirm all utilities classify their water as "slightly or moderately hard." The Williamson County limestone formation means even treated surface water carries noticeable hardness compared to national averages.
7.9 GPG (135 PPM avg)
Franklin city water hardness — source: primary utility and CCR data
Hard
10–18+ GPG
Private wells in Williamson County limestone aquifers — significantly above city supply
Extremely Hard
Salt-free conditioners fail at 7+ GPG
Ion exchange water softener strongly recommended for Franklin homes — especially tankless water heater owners
Franklin Neighborhood Water Guide — Find Your Area
Franklin residents search by neighborhood, not by utility. Here's what you need to know based on where you live — and which utility most likely serves your address. Always confirm on your water bill.
Westhaven
37064
Likely utility
Franklin Water Dept. or H.B.&T.S.
Moderately hard water at ~7.9 GPG (135 PPM) causes scale on fixtures and threatens tankless water heaters common in Westhaven's new builds. Disinfection byproducts (TTHMs, chloroform) are the primary chemical concern. An activated carbon whole-house filter plus a softener is the recommended combination for most Westhaven homes.
Berry Farms
37064
Likely utility
Franklin Water Dept.
One of Franklin's fastest-growing new construction areas. Franklin Water Dept. customers here should note the elevated chlorate (591 ppb — 5x state average) alongside standard DBP concerns. New build homes almost universally include tankless water heaters — hard water protection is critical from day one.
Cool Springs
37067
Likely utility
H.B.&T.S. or Harpeth Valley
Cool Springs commercial and residential areas draw from purchased surface water with similar DBP profiles to Franklin WD. H.B.&T.S. detected bromodichloromethane at 118x EWG guidelines — the highest of any local utility. Check your bill to confirm your provider; filter recommendations are the same across utilities.
Downtown Franklin
37064
Likely utility
Franklin Water Dept.
Historic downtown Franklin includes older housing stock. Chlorate is the standout concern for Franklin WD customers (591 ppb, 2.8x EWG guideline). Older homes with galvanized plumbing may also see elevated lead or manganese from internal pipes — independent of the utility supply. An under-sink RO system is the most practical protection for drinking water.
Fieldstone Farms / Avalon
37069
Likely utility
Milcrofton or Harpeth Valley
Milcrofton and Harpeth Valley serve much of the 37069 zip code. Both have 9–10 contaminants above EWG guidelines with similar DBP profiles to Franklin WD. Milcrofton nitrate is within EWG guidelines — a slight advantage over Franklin WD. Same filtration approach applies: whole-house carbon plus RO for drinking.
Mack Hatcher / South Franklin
37064 / 37069
Likely utility
Mallory Valley or Franklin WD
Mallory Valley Utility District has the most contaminants above EWG guidelines (11 of 19 detected) of any local utility — including PFAS above EWG thresholds. If your address is on Mallory Valley, an under-sink RO system for drinking water is particularly warranted. Check your bill carefully in this area — the utility boundary runs through this corridor.
Not sure which utility serves your address? Check your water bill — the utility name and phone number appear on the first page. You can also look up your PWS ID in the EWG Tap Water Database by zip code or call Franklin Water Management at 615-794-4572.
New Build in Franklin? Read This Before Your Water Heater Fails
Franklin is one of the fastest-growing cities in Tennessee. Westhaven, Berry Farms, Avalon, Fieldstone Farms — thousands of new homes are built here every year, and virtually every one includes a tankless water heater. At 7.9 GPG (135 PPM), Franklin's moderately hard water is a slow, invisible threat to that investment that no builder will warn you about at closing.
The Tankless Water Heater Problem in Franklin, TN
Why your builder's warranty doesn't cover what hard water does to your new home
What happens without a softener
Year 1–2
Calcium scale begins accumulating on the heat exchanger. Flow rates start to drop slightly. No visible symptoms yet.
Year 2–4
Scale narrows the heat exchanger passages. Error codes begin appearing. Energy costs increase 20–30% as the unit works harder to heat water through insulating scale.
Year 4–6
Heat exchanger failure. Replacement cost: $1,200–$3,000 for the unit plus installation. Most manufacturer warranties are voided by documented hard water damage above 7 GPG without a softener.
The manufacturer warranty reality
Major tankless water heater brands — including Rinnai, Navien, Rheem, and Noritz — explicitly state in their warranty documentation that damage caused by hard water scale is not covered. At Franklin's 7.9 GPG, you are operating at the threshold where most manufacturers recommend a water softener to maintain warranty validity.
TWA recommendation for new Franklin builds
Install a water softener before or immediately after move-in. At 7.9 GPG, this is not optional — for tankless heater longevity. A 48,000 grain demand-initiated softener from a local independent dealer costs $2,500–$4,500 installed — significantly less than one heat exchanger replacement, and it protects every appliance in the home simultaneously.
Source: WQA scale damage research; U.S. Dept. of Energy scale-efficiency data; tankless manufacturer warranty documentation. Franklin hardness verified at 7.9 GPG (135 PPM).
Williamson County Hard Water Impact Calculator
Enter your water's hardness reading — from a test kit, your CCR, or a lab report — to see your classification, appliance lifespan impact, and the softener size your home needs.
Harpeth River Limestone & Hard Water Impact Calculator
Defaults set to typical Franklin city water levels. Adjust sliders to match your specific test results.
Hard — Franklin city water average (7.9 GPG / 135 PPM)
Scaling Risk Rating
High Scale Alert
Limestone minerals from the Harpeth River solidify rapidly at higher temperatures
Estimated Appliance Lifespan Reduction
48% Faster Degradation
vs. a home with soft water (0–1 GPG)
Water heater efficiency loss
−20%
Scale insulation forces heater to work harder
Dishwasher & washer lifespan
−32%
Mineral buildup on heating elements
Recommended softener size
48,000 grain system
Based on WQA sizing formula for your household & hardness
At 7.9 GPG (135 PPM) — Franklin's verified CCR average for most utilities — water is classified as moderately hard. Scale accumulates gradually in hot water systems. Tankless water heaters are the most sensitive appliances at this hardness level. A softener is a practical investment for new construction or appliance protection.
Chlorine Residual in Franklin Water
Franklin Water Department uses chlorine as its primary disinfectant. While chlorine effectively kills bacteria and viruses, the residual that reaches your tap is worth knowing — especially because it directly drives the formation of the disinfection byproducts (TTHMs, HAAs, chloroform, bromodichloromethane) that are Franklin’s biggest water quality concerns.
Pool-Level Chlorine
Franklin tap water runs at pool-level chlorine concentration
Franklin Water Department’s estimated chlorine residual is approximately 1.70 ppm at the tap. For comparison, the EPA-recommended range for a swimming pool is 1.0–3.0 ppm — meaning your Franklin tap water likely contains chlorine at roughly the same concentration as pool water. This is within legal limits and effective for disinfection, but it is the direct cause of the elevated TTHMs and haloacetic acids in Franklin water. An NSF/ANSI 42-certified activated carbon filter removes chlorine taste and odor completely and reduces the formation of disinfection byproducts at the point of use.
~1.70
ppm Franklin WD (est.)
1.0–3.0
ppm EPA pool range
0.0
ppm after activated carbon
Bottom line: You cannot taste or smell chlorine at 1.70 ppm the way you do in a pool because pool water is on your skin, not passing through your palate. But the chemistry is the same — and in Franklin water it reacts with source water organic matter (Harpeth River for Franklin WD; Cumberland River via HVUD for H.B.&T.S., Milcrofton, and Mallory Valley) to form bromodichloromethane at 100x EWG guidelines. A whole-house activated carbon system is the most effective way to intercept chlorine before it reacts with your pipes and fixtures.
What chlorine at pool levels does to your body and home
Skin
Chlorine strips the skin’s natural oils and disrupts the moisture barrier. At 1.70 ppm — daily shower exposure — it causes dryness, itching, and irritation. People with eczema or sensitive skin often notice significant improvement after installing a whole-home carbon filtration system.
Hair
Chlorine oxidizes hair proteins, breaking down the outer cuticle layer. This causes dryness, frizz, brittleness, and color fade in dyed hair. At pool-range concentrations, daily washing strips the natural sebum that keeps hair supple. A shower-head carbon filter or whole-house system prevents this entirely.
Gut Health
Chlorine is an antimicrobial agent — that is exactly why utilities use it. Consumed daily in drinking water, it does not distinguish between harmful pathogens and beneficial gut microbiome bacteria. Emerging research links chronic chlorinated water consumption to microbiome disruption and digestive sensitivity. An under-sink carbon or RO filter removes chlorine from drinking water completely.
Laundry
Chlorine bleaches and degrades fabric fibers over time, causing colors to fade faster, whites to yellow, and fabrics to wear thin sooner than they should. This is especially noticeable on dark clothing and athletic wear. Whole-house activated carbon filtration extends the life of clothes and towels significantly — a measurable return on investment over time.
Eyes & Mucous Membranes
The same pool-level chlorine that causes red, irritated eyes when swimming is present in your shower steam. Daily inhalation of chlorinated steam during showers exposes mucous membranes to chlorine gas byproducts. People with asthma or respiratory sensitivity often notice shower-steam irritation that disappears after installing a carbon shower filter.
Pets & Plants
Dogs and cats absorb chlorine through their skin and ingest it while drinking tap water. Many pet owners report improved coat condition after switching to filtered water. Chlorinated water also stresses chlorine-sensitive houseplants — fiddle leaf figs, ferns, and tropical plants in particular. Letting tap water sit overnight allows some chlorine to off-gas, but carbon filtration removes it completely and instantly.
The fix is simple and affordable. An NSF/ANSI 42-certified activated carbon filter — whether whole-house or under-sink — removes chlorine completely at the point of use. For Franklin homes concerned about both chlorine and the disinfection byproducts it creates (bromodichloromethane 100x EWG, TTHMs, HAAs), a whole-house carbon system addresses both problems in one installation. See the filter recommendations below for Franklin-specific sizing and pricing.
Filter Recommendations for Franklin Homes
Franklin's water profile has two distinct layers: disinfection byproducts from chlorination of surface water — Harpeth River (Franklin WD) or Cumberland River via HVUD (H.B.&T.S., Milcrofton, Mallory Valley) — the primary chemical concern and hard water from Williamson County limestone (the primary home infrastructure concern). The chlorate situation adds a third consideration unique to Franklin Water Department customers.
The Franklin Water Treatment Recommendation
1.
Whole-house activated carbon backwashing filter
Addresses the primary concern — TTHMs, HAAs, chloroform, bromodichloromethane, and chlorine throughout your entire home. Franklin's chloroform level (36.4 ppb — 2x the state average) makes this particularly important. Cost: $1,400–$4,500 installed from a local independent dealer.
Under-sink reverse osmosis — drinking & cooking water
Removes PFOA, nitrate, chromium-6, chlorate, and any remaining byproducts. For Franklin Water Department customers especially, RO is the most effective way to address the elevated chlorate level (591 ppb). NSF/ANSI 58 certified. Cost: $600–$2,000 installed under-sink.
Removes: PFOA Chlorate Nitrate Chromium-6 All DBPs
3.
Water softener — ion exchange, demand-initiated
Addresses Williamson County's hard water (7.9 GPG). Essential for homes with tankless water heaters, premium appliances, or new construction. A properly sized 48,000–64,000 grain system handles most Franklin households. Cost: $2,500–$4,500 installed.
Removes: Ca/Mg hardness Barium Radium
Franklin Water Dept. customers with young children or during pregnancy: The elevated chlorate level (591 ppb — 2.8x EWG guideline, 5x state average) specifically concerns thyroid function. An under-sink reverse osmosis system at the kitchen tap is the most practical and effective protection for drinking and cooking water. This is a precautionary recommendation, not an emergency — the water is within EPA legal limits.
Yes. All five Franklin-area utilities were in full compliance with all EPA health-based drinking water standards as of the latest quarterly assessment (April–June 2024). EWG exceedances are not regulatory violations — they reflect the gap between EPA legal limits (not updated in nearly 20 years) and EWG's more conservative health thresholds. Franklin's water is legally safe. This guide helps you decide whether additional filtration makes sense for your family's priorities.
Several things stand out. First, Franklin is served by five separate utilities vs. Nashville's single Metro Water Services system — knowing which utility serves your specific address matters. Second, Franklin Water Department's chloroform level (36.4 ppb) is more than double Tennessee's state average (17.7 ppb) — notably higher than most Middle Tennessee peers. Third, the chlorate level (591 ppb) at Franklin Water Dept. is 5x the state average — a concern unique to Franklin that most water guides don't cover. Fourth, Williamson County water is generally harder (8–13 GPG) than Metro Nashville (~6 GPG).
Check your water bill — the utility name and contact number appear on the first page. Franklin city limits are generally served by Franklin Water Department. Cool Springs, Westhaven, and outlying Williamson County areas may be served by H.B.&T.S. Utility District, Harpeth Valley Utility District, Mallory Valley Utility District, or Milcrofton Utility District. You can also call Franklin Water Management at the city's main line or search your address in the EWG Tap Water Database at ewg.org/tapwater.
Chlorate forms when sodium hypochlorite (liquid bleach) — used for water disinfection — degrades or reacts during treatment. Franklin Water Department detected it at 591 ppb, which is 2.8x EWG's health guideline and 5x the Tennessee state average. Chlorate impairs thyroid function by blocking iodine uptake, making it most concerning during pregnancy and childhood. No EPA legal limit currently exists for chlorate. Reverse osmosis is the most effective way to reduce chlorate in drinking water; activated carbon also provides reduction.
Franklin city water hardness is confirmed at 135 PPM (7.9 GPG) in the 2025 CCRs for H.B.&T.S., HVUD, and Mallory Valley — classified as moderately hard on the WQA scale. Franklin Water Department (Harpeth River source) may vary slightly. Private wells in Williamson County limestone aquifers frequently test 10–18+ GPG. Even at 7.9 GPG, a water softener is beneficial for homes with tankless water heaters and high-end appliances. Salt-free conditioners are less effective at these hardness levels.
For most Franklin homes: (1) A whole-house activated carbon backwashing filter ($1,400–$4,500 installed) addresses disinfection byproducts — TTHMs, HAAs, and chloroform — throughout the entire home. Given Franklin's above-average chloroform levels this is especially warranted. (2) An under-sink reverse osmosis system ($600–$2,000 installed) provides comprehensive protection for drinking and cooking water, including chlorate, nitrate, chromium-6, and PFOA. (3) A water softener ($2,500–$4,500) addresses Williamson County's hard water to protect appliances and improve daily water quality.
