Thompson’s Station · Williamson & Maury Counties · 6 Utilities · EWG 2024 Data
Thompson’s Station, TN Water Quality Guide 2026
What’s in your Thompson’s Station tap water — drawn from EWG’s database covering six Williamson and Maury County utilities. H.B.&T.S. Utility District — the utility most directly serving Thompson’s Station (37179) — has 9 of 13 above EWG guidelines from purchased surface water. Franklin Water Department has bromodichloromethane at 6.01 ppb (100x EWG). Spring Hill Water Department has 10 of 21 above EWG. Milcrofton UD has PFOA above EWG. The Harpeth River and Duck River are the primary sources for this area. Hardness: 7.9 GPG verified. Here’s what every number means and what removes it.
Updated June 2026Sources: EWG Tap Water Database (2013–2024) · Franklin WD 2025 CCR · Six utility profilesIndependent — Tennessee Water Authority
Thompson's Station, Tennessee — Founded 1798. One of Williamson County's oldest communities, now served by six separate utilities with significantly different water quality profiles depending on your address.
Data sources: EWG Tap Water Database (H.B.&T.S. UD 2014–2024, Franklin WD 2014–2023, Spring Hill WD 2014–2023, Milcrofton UD 2014–2023, Maury County WS 2013–2024). Franklin WD hardness (7.9 GPG) verified from 2025 CCR. All utilities in full EPA compliance April–June 2024.
Legal limits do not equal optimal health. All contaminants on this page are within EPA legal limits. All six utilities were in full EPA compliance as of April–June 2024. EWG exceedances reflect EWG’s more conservative health thresholds — not regulatory violations. Thompson’s Station water is legally safe to drink.
Verified hardness (Franklin WD 2025 CCR) Harpeth River · Hard zone
PFOA
Above EWG in Milcrofton UD & Spring Hill WD EPA MCL: 4 ppt (April 2024)
Six Utilities Serving Thompson’s Station (37179)
Thompson’s Station sits at the convergence of Williamson and Maury counties, just south of Franklin and Spring Hill. Depending on your specific street address, you may be served by any of six utilities. H.B.&T.S. Utility District is the most directly associated with Thompson’s Station (37179 zip code). Check your water bill to confirm your utility.
Williamson Co.Most 37179 addresses served by HBTS UD, Franklin WD, or Milcrofton UD
Thompson’s Station: where the Harpeth River and Duck River watersheds meet
Thompson’s Station sits on the Williamson/Maury county line, served by utilities drawing from two distinct river sources. Franklin Water Department and H.B.&T.S. UD draw from the Harpeth River watershed. Spring Hill Water Department and Maury County Water System draw from the Duck River. Both rivers flow through Tennessee’s limestone geology, producing similar contaminant profiles — disinfection byproducts from chlorination, chromium-6 from mineral deposits, and nitrate from agricultural runoff. PFOA is detected above EWG guidelines in both Milcrofton UD and Spring Hill WD.
Spring Hill WD contaminants above EWG — most of the six utilities, PFOA included
7.9 GPG
Verified hardness (Franklin WD 2025 CCR) — Harpeth River · Hard zone
9 GPG
Estimated HBTS UD / Milcrofton UD hardness from same Harpeth River / Williamson Co. limestone source
Contaminants Exceeding EWG Health Guidelines
All contaminants below are within EPA legal limits. All six utilities were in full EPA compliance as of April–June 2024. EWG data spans 2013–2024 depending on utility. Franklin WD 2025 CCR provides the most current verified hardness data.
Disinfection Byproducts — Primary concern across all six utilities from river chlorination
Bromodichloromethane — Franklin WD 100x EWG
Disinfection Byproduct (TTHM component) — above EWG in all six utilities
100x
Franklin WD 6.01 ppb · EWG guideline 0.06 ppb · all six utilities above EWG
Franklin Water Dept. (EWG 2014–2023)
6.01 ppb · 100x EWG Harpeth River source
above TN avg (3.91) AND national avg (5.89)
H.B.&T.S. Utility District (EWG 2014–2024)
Above EWG (0.06 ppb) purchased surface water
primary Thompson’s Station utility
Maury County / Spring Hill / Milcrofton (EWG)
All above EWG guideline Harpeth & Duck River sources
duck river and Harpeth River chlorination
Health concern: Cancer risk and harm to fetal development. Franklin WD’s 6.01 ppb exceeds both the Tennessee state average (3.91 ppb) and the national average (5.89 ppb). All six utilities in this guide show bromodichloromethane above EWG’s conservative 0.06 ppb guideline — a reflection of the Harpeth and Duck Rivers’ organic matter reacting with chlorine during treatment. All within EPA legal limits. Whole-house activated carbon is the most effective whole-home treatment.
Total TTHMs & Haloacetic Acids (HAA5 & HAA9)
Disinfection Byproduct Groups — all six utilities above EWG
Above EWG
All six utilities · EWG: TTHMs 0.15 ppb / HAA5 0.1 ppb · EPA: 80/60 ppb
H.B.&T.S. UD & Milcrofton UD
TTHMs and HAA5/HAA9 above EWG EWG historical data
purchased surface water · Williamson County
Franklin WD & Spring Hill WD
TTHMs and HAA5 above EWG Harpeth River and Duck River sources
all within EPA 80/60 ppb limits
Maury County Water System
TTHMs and HAAs above EWG EWG 2013–2024 data
purchased surface water · Maury County
Key context: TTHMs and HAAs form when chlorine reacts with natural organic matter in river water during treatment. The Harpeth River and Duck River both carry organic matter that drives TTHM formation. All six area utilities show these byproducts above EWG’s conservative guidelines — all within EPA legal limits. Whole-house activated carbon is the most effective whole-home treatment; RO provides the most complete removal for drinking and cooking.
PFAS "Forever Chemicals" — Above EWG in Milcrofton UD and Spring Hill WD
PFOA & PFOS (Forever Chemicals)
PFAS — Milcrofton UD & Spring Hill WD above EWG
Above EWG
Milcrofton UD & Spring Hill WD · EWG: 0.09 ppt · EPA new MCL: 4 ppt (April 2024)
Milcrofton UD & Spring Hill WD (EWG data)
PFOA above EWG guideline (0.09 ppt) Williamson County / Duck River area
EPA MCL: 4 ppt (2024 rule) · utilities have until 2029
H.B.T.S. UD / Franklin WD / Maury County
PFAS not reported or not specified in current EWG data
UCMR 5 monitoring ongoing nationally
Health concern: Cancer, immune suppression, thyroid disruption. The EPA finalized a 4 ppt MCL for PFOA/PFOS in April 2024 — utilities have until 2029 to comply. PFOA is detected above EWG’s conservative 0.09 ppt guideline in both Milcrofton UD and Spring Hill Water Department. Reverse osmosis is the most complete household PFAS treatment.
Industrial Contaminants
Chromium (Hexavalent / Cr-6)
Industrial / Naturally Occurring — all six utilities above EWG
Above EWG
All six utilities · EWG: 0.02 ppb · no federal MCL for Cr-6
All six area utilities (EWG data)
Chromium-6 above EWG guideline (0.02 ppb)
No separate EPA MCL for hexavalent chromium
Source
Naturally occurring in Williamson and Maury County geological formations and the Harpeth River / Duck River watersheds. Common across Middle Tennessee surface water utilities. Carbon filters are NOT effective for Cr-6.
Health concern: Known human carcinogen. No federal MCL specifically for hexavalent chromium. Reverse osmosis or ion exchange required for effective removal. Carbon filters do not remove Cr-6.
Agricultural Contaminants
Nitrate — Above EWG in all six utilities
Agricultural Runoff
Above EWG
All six utilities · EWG: 0.14 ppm · EPA: 10 ppm · all well within EPA limit
All six area utilities (EWG data)
Nitrate above EWG guideline (0.14 ppm)
All well within EPA 10 ppm acute limit
Franklin WD (2025 CCR verified)
Nitrate above EWG guideline · confirmed in 2025 CCR
Harpeth River watershed agricultural runoff
Health concern: No area utility approaches the EPA 10 ppm acute nitrate limit. No acute risk for adults. For infants under 6 months, use RO-filtered water for all formula preparation — never boiled tap water, which concentrates nitrate. Carbon filters do NOT remove nitrate.
All Six Utilities — Side-by-Side Comparison
Contaminant
EWG / EPA Limit
H.B.T.S. UD TN0000699
Franklin WD TN0000246
Spring Hill WD TN0000667
Milcrofton UD TN0000247
Maury Co. WS TN0000770
Source
—
Purchased surface water
Harpeth River
Duck River
Purchased surface water
Purchased surface water
TTHMs
0.15 ppb / 80 ppb
Above EWG
Above EWG
Above EWG
Above EWG
Above EWG
HAA5 & HAA9
0.1 ppb / 60 ppb
Above EWG
Above EWG
Above EWG
Above EWG
Above EWG
Bromodichloromethane
0.06 ppb
Above EWG
6.01 ppb · 100x
Above EWG
Above EWG
Above EWG
PFOA / PFOS
0.09 ppt / 4 ppt
Not in EWG data
Not in EWG data
Above EWG
Above EWG
Not specified
Chromium-6
0.02 ppb
Above EWG
Above EWG
Above EWG
Above EWG
Above EWG
Nitrate
0.14 ppm / 10 ppm
Above EWG
Above EWG (2025 CCR)
Above EWG
Above EWG
Above EWG
Hardness
—
~7–9 GPG est.
7.9 GPG verified (2025 CCR)
~9 GPG est. (Duck River)
~8–9 GPG est.
~9 GPG est.
EPA Compliance (Apr–Jun 2024)
—
Full compliance
Full compliance
Full compliance
Full compliance
Full compliance
Above EWG / Total
—
9 of 13
10 of 17
10 of 21
9 of 14
10 of 20
Protecting Children & Pregnant Women in Thompson’s Station
Thompson’s Station’s rapid growth has brought many young families to the area. Disinfection byproducts and PFOA (in Milcrofton UD and Spring Hill WD) are the primary concerns for pregnant women and young children.
TTHMs, HAAs & Pregnancy
Disinfection byproducts have been linked in studies to pregnancy complications including low birth weight and preterm birth at sustained exposure levels. All six area utilities show TTHMs and HAAs above EWG’s conservative guidelines from Harpeth River and Duck River chlorination. The first trimester is the highest-risk window. A whole-house carbon filter plus under-sink RO provides the most complete protection during pregnancy.
PFOA & Children’s Development
PFOA is detected above EWG’s conservative guidelines in both Milcrofton UD and Spring Hill Water Department. Studies link PFAS to immune suppression, thyroid disruption, and developmental effects in children exposed during pregnancy and early childhood. Reverse osmosis provides the most complete household PFAS removal. If served by Milcrofton UD or Spring Hill WD, RO is the priority drinking water investment.
Nitrate & Infants Under 6 Months
No area utility approaches the EPA 10 ppm acute nitrate limit. For infants under 6 months, use RO-filtered water for all formula preparation. Never boil tap water for infant formula — boiling concentrates nitrate rather than removing it. Carbon filters do NOT remove nitrate.
Lead & Home Plumbing
Specific lead testing results for Thompson’s Station utilities are not listed in this guide’s current EWG data. All utilities are in EPA compliance. However, lead can come from home plumbing in pre-1986 homes regardless of utility results. Flush cold tap 30 seconds before use in older homes. Use NSF/ANSI 53 certified filter for drinking in any pre-1986 home.
Four actions for Thompson’s Station families with young children or pregnancy
1.Install a whole-house activated carbon filter — reduces TTHMs and HAAs from Harpeth River and Duck River chlorination at every tap and shower.
2.Install an NSF/ANSI 58 certified RO system at the kitchen sink — removes TTHMs, HAAs, PFOA (Milcrofton UD & Spring Hill WD customers especially), chromium-6, and nitrate.
3.Use RO-filtered water for all infant formula preparation — never boiled tap water, which concentrates nitrate.
4.In older homes (pre-1986), flush cold tap 30 seconds before using water that has sat overnight. Never use hot tap water for drinking or formula.
Your Pets & Thompson’s Station Water Quality
The same disinfection byproducts and PFOA detected in Thompson’s Station area water affect pets at proportionally higher exposure per unit body weight.
Dogs & Cats
A 15-pound dog receives roughly 10x the relative TTHM exposure per pound of body weight compared to a 160-pound adult. Long-term TTHM exposure has been associated with elevated bladder cancer risk in some dog breeds. Fill your pet’s bowl from your RO-filtered tap.
Small Animals, Birds & Reptiles
Rabbits, guinea pigs, hamsters, and birds have tiny body masses — their relative contaminant exposure is far higher than a human’s. PFOA accumulates in animal tissue over time. RO-filtered water is strongly recommended for all small caged animals and birds.
Aquarium Fish & Aquatic Pets
Chlorine in area tap water is directly toxic to fish and aquarium invertebrates. Never add untreated tap water to a tank. Activated carbon removes free chlorine. RO is the gold standard for sensitive species, reef tanks, and shrimp. Never boil tap water for aquarium use.
What to Do for Your Pets
Dogs and cats: RO-filtered tap water for their bowl. Whole-house carbon is a meaningful improvement. Small animals and birds: RO or filtered water strongly recommended. Fish: Always dechlorinate tap water. Use RO for sensitive species.
What Hard Water Is Doing to Your Thompson’s Station Home Every Day
Williamson County sits on limestone geology through which the Harpeth River flows before reaching water treatment plants. Franklin WD’s 2025 CCR confirms 7.9 GPG — solidly in the Hard zone. The Duck River watershed adds similar mineral content for Spring Hill WD and Maury County WS customers. Treatment does not remove hardness.
Skin & Hair
At 7.9 GPG (Hard zone), calcium and magnesium ions disrupt the skin’s moisture barrier after showering — noticeable dryness, irritation, and eczema risk for children. Hair feels coarser and dull. Color-treated hair fades faster in Williamson County hard water than in soft water areas.
Dishes & Glassware
White spots and cloudy calcium carbonate film on glassware and dishes. At 7.9 GPG, dishwasher detergent needs 50–75% more product to be effective. Thompson’s Station’s new construction typically has modern dishwashers that display calcium buildup within months on untreated water. A softener eliminates spotting entirely.
Laundry
Mineral deposits build up in fabric fibers at 7.9 GPG — clothes feel stiffer, whites yellow faster, colors fade, towels lose absorbency. Clothes washed in Hard water wear out up to 15% faster. A softener restores full detergent effectiveness and extends garment life significantly.
Water Heater & Appliances
Scale reduces water heater efficiency 8% per GPG (U.S. Dept. of Energy). At 7.9 GPG, scale accumulates meaningfully in hot water systems. Thompson’s Station’s new construction with tankless water heaters and premium appliances is especially sensitive. A softener is a strong investment for appliance life.
Harpeth River Limestone — Hard Water in Thompson’s Station
Franklin Water Department’s 2025 CCR is the most reliable hardness reference for the area — confirming 7.9 GPG from the Harpeth River. H.B.&T.S. UD and Milcrofton UD purchase surface water from the same Harpeth River / Williamson County limestone watershed, so hardness is expected to be comparable (7–9 GPG). The Duck River source for Spring Hill WD and Maury County WS produces similar hardness (estimated 8–9 GPG).
7.9 GPG
Franklin WD 2025 CCR verified — Harpeth River · Hard zone
Hard (Franklin WD 2025 verified)
7–9 GPG
H.B.T.S. UD / Milcrofton UD estimated — same limestone watershed
Hard zone (estimated)
8–9 GPG
Spring Hill WD / Maury County WS estimated — Duck River limestone
Hard zone (estimated)
Thompson’s Station Hard Water Impact Calculator
Harpeth River / Williamson County Limestone Hard Water Calculator
Default: 8 GPG — estimated typical Thompson’s Station range based on Franklin WD 2025 CCR (7.9 GPG verified).
Soft 0–3Mod. Hard 3–5Hard 7–10Extremely Hard 10.5+
Hard — Thompson’s Station typical range (Franklin WD: 7.9 GPG verified 2025)
Scaling Risk Rating
High Scale Alert
Harpeth River limestone minerals accumulate in hot water systems
Estimated Appliance Lifespan Reduction
39% Faster Degradation
vs. a home with soft water (0–1 GPG)
Water heater efficiency loss
-16%
Scale on heating elements
Dishwasher & washer lifespan
-26%
Mineral buildup
Recommended softener size
48,000 grain system
WQA sizing for your household & hardness
At 8 GPG — Thompson’s Station’s estimated Hard zone (Franklin WD verified 7.9 GPG). Scale accumulates in hot water systems over 2–4 years. A properly sized softener is strongly recommended for new construction with tankless water heaters.
Thompson’s Station & Surrounding Area Water Guide
Which utility serves your Thompson’s Station address depends on your specific location in Williamson or Maury County. Check your water bill to confirm.
Find Your Area
Thompson’s Station (37179)
37179
Primary Utility
H.B.&T.S. Utility District
H.B.&T.S. Utility District (TN0000699) serves 37,803 from purchased Williamson County surface water. 9/13 above EWG. TTHMs, HAAs, bromodichloromethane, chromium-6, and nitrate detected above EWG guidelines. In full EPA compliance April–June 2024. Check your water bill to confirm — Franklin WD, Milcrofton UD, or Spring Hill WD may serve your specific address.
Franklin / N. Williamson County
37064, 37067, 37069
Utility
Franklin Water Department
Franklin WD (TN0000246) serves 77,411 from the Harpeth River. 10/17 above EWG. Bromodichloromethane 6.01 ppb (100x EWG) — above TN avg and national avg. Hardness 7.9 GPG verified (2025 CCR). PFOA above EWG. In full EPA compliance. See Franklin TN Water Guide for full detail.
Spring Hill / S. Williamson / N. Maury
37174
Utility
Spring Hill Water Department
Spring Hill WD (TN0000667) serves 60,893 from the Duck River. 10/21 above EWG — most of the six utilities. PFOA above EWG. TTHMs, HAAs, bromodichloromethane, chromium-6, and nitrate above EWG. In full EPA compliance. See Spring Hill TN Water Guide for full detail.
Milcrofton / Central Williamson Co.
37027 (parts)
Utility
Milcrofton Utility District
Milcrofton UD (TN0000247) serves 33,605 from purchased surface water. 9/14 above EWG. PFOA above EWG guideline. TTHMs, HAAs, chromium-6, and nitrate above EWG. In full EPA compliance. Contact your local utility office or check your water bill to confirm.
Maury County / S. of Thompson’s Station
38401 (parts)
Utility
Maury County Water System
Maury County Water System (TN0000770) serves 23,118 from purchased surface water. 10/20 above EWG. Bromodichloromethane, TTHMs, HAAs, chromium-6, and nitrate above EWG. In full EPA compliance April–June 2024. See Columbia TN Water Guide for Maury County area detail.
All six Thompson's Station-area utilities — Milcrofton UD, Spring Hill WD, and Marshall County WA — use chlorine as their 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 Spring Hill’s biggest water quality concerns.
Pool-Level Chlorine
Thompson's Station tap water runs at pool-level chlorine concentration
Thompson's Station-area utilities run chlorine residuals estimated at 1.50–1.80 ppm at the tap. For comparison, the EPA-recommended range for a swimming pool is 1.0–3.0 ppm — meaning your Thompson's Station tap water 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 Thompson's Station 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.
~1.65
ppm Thompson's Station area (est.)
1.0–3.0
ppm EPA pool range
0.0
ppm after activated carbon
Bottom line: You cannot taste or smell chlorine at ~1.65 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 Thompson's Station water it reacts with Duck River organic matter to form chloroform at 102x EWG and PFOA above 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 ~1.65 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 Thompson's Station homes concerned about chlorine, BrCHM 100x EWG, and PFOA above EWG, TTHMs, HAAs), a whole-house carbon system addresses both problems in one installation. See the filter recommendations below for Thompson's Station-specific sizing and pricing.
Filter Recommendations for Thompson’s Station Homes
Disinfection byproducts are the dominant concern across all six utilities. PFOA in Milcrofton UD and Spring Hill WD adds RO as a priority for those customers. Williamson County limestone hardness (7.9 GPG verified at Franklin WD) makes a softener a strong investment for appliance protection.
The Thompson’s Station Water Treatment Recommendation
1.
Whole-house activated carbon backwashing filter
Addresses TTHMs, HAAs, bromodichloromethane, and chlorine from Harpeth River and Duck River chlorination at every tap, shower, and appliance. Franklin WD’s 6.01 ppb bromodichloromethane (100x EWG) is the most elevated single contaminant in this guide. H.B.&T.S. UD, Spring Hill WD, Milcrofton UD, and Maury County WS customers all benefit significantly. Cost: $1,400–$4,500 installed.
Removes PFOA (Milcrofton UD and Spring Hill WD customers: priority), chromium-6 (not removable by carbon), nitrate, and all remaining byproducts. NSF/ANSI 58 certified. Provides the best future insurance for all customers against PFAS if monitoring for H.B.T.S. UD or Franklin WD shows detection. Cost: $600–$2,000 installed.
Removes: PFOA · Chromium-6 · Nitrate · All DBPs
3.
Water softener — ion exchange, demand-initiated
Addresses Harpeth River limestone hardness (7.9 GPG verified at Franklin WD — Hard zone). Thompson’s Station’s abundant new construction with tankless water heaters is especially sensitive to scale. A properly sized 32,000–48,000 grain system handles most households. Cost: $2,500–$4,500 installed.
Frequently Asked Questions — Thompson’s Station TN Water
Yes. All six utilities serving Thompson’s Station area were in full compliance with federal EPA health-based drinking water standards as of April–June 2024. EWG exceedances are not regulatory violations. Thompson’s Station water is legally safe to drink. The primary concerns are disinfection byproducts (TTHMs, HAAs, bromodichloromethane) from Harpeth River and Duck River chlorination, and PFOA in Milcrofton UD and Spring Hill WD — all within EPA legal limits.
Thompson’s Station 37179 is served by multiple utilities depending on your specific street address. H.B.&T.S. Utility District (TN0000699) is the utility most directly associated with Thompson’s Station, serving 37,803 in Williamson County from purchased surface water. Franklin Water Department, Spring Hill Water Department, and Milcrofton Utility District also serve parts of the 37179 area. Check your water bill to confirm which utility serves your address. You can also search at EWG’s database for 37179.
Depends on your utility. Franklin Water Department draws from the Harpeth River. H.B.&T.S. Utility District and Milcrofton UD purchase treated surface water from Williamson County sources (likely Harpeth River watershed). Spring Hill Water Department draws from the Duck River. Maury County Water System purchases surface water. All sources are in the Harpeth River or Duck River watershed — rivers that flow through Williamson and Maury County limestone geology.
Franklin Water Department’s 2025 CCR confirms hardness at 7.9 GPG (Harpeth River) — solidly in the Hard zone. H.B.&T.S. UD and Milcrofton UD purchase from the same Harpeth River / Williamson County limestone watershed, so hardness is expected to be comparable (7–9 GPG). Spring Hill WD and Maury County WS use the Duck River, which produces similar limestone-derived hardness (estimated 8–9 GPG). A water softener is a strong investment for appliance protection at these hardness levels.
For most Thompson’s Station homes: (1) Whole-house activated carbon filter ($1,400–$4,500) for TTHMs and HAAs from Harpeth River / Duck River chlorination at every tap and shower. (2) Under-sink RO ($600–$2,000) for PFOA (especially important for Milcrofton UD and Spring Hill WD customers), chromium-6, and nitrate. (3) Water softener ($2,500–$4,500) for Williamson County limestone hard water (7.9 GPG verified at Franklin WD).
PFOA is detected above EWG’s conservative 0.09 ppt guideline in Milcrofton Utility District and Spring Hill Water Department per EWG historical data. H.B.&T.S. UD, Franklin WD, and Maury County WS PFAS data is not specified in current EWG data. The EPA finalized a 4 ppt MCL for PFOA/PFOS in April 2024; utilities have until 2029 to comply. Reverse osmosis provides the most complete household PFAS treatment regardless of which utility serves your address.
