Is Plymouth, MN Tap Water Safe to Drink?
Yes, Plymouth tap water is safe to drink. No contaminants exceed health guidelines. However, Plymouth has very hard water at 254 PPM, which will cause scale buildup in plumbing and appliances over time. A water softener is worth considering.
Hardness Scale: Where Plymouth Falls
0Slightly
60Moderate
120Hard
180Very Hard
250Extreme
400+
How Plymouth Compares
Plymouth's water is 84% harder than the national average of 138 PPM. It ranks #168 out of 1000 cities in our database (harder than 83% of US cities we track). Within Minnesota, it ranks #7 of 16 cities (18% above the state average of 216 PPM). Among cities (50k-100k), Plymouth ranks #54 of 258 for hardness. At this hardness level, water heaters run an estimated 47% less efficiently due to scale insulation, and major water-using appliances typically last 4 years less than the national average lifespan.
What Plymouth's Water Means for Your Home
Hardness: 254 PPM - Treatment Recommended
Plymouth has some extremely hard water. At 254 PPM (14.9 grains per gallon), your tap is loaded with dissolved calcium and magnesium picked up from underground limestone and dolomite formations. Here's the thing: it's perfectly safe to drink. The minerals won't hurt you. But they will hurt your wallet. That adds up. Hard water at 254 PPM increases household costs through scale-coated water heaters that use more energy, extra soap and detergent, and appliances that wear out faster. Most Plymouth homeowners don't realize it until the plumber shows up. That's 18% harder than the Minnesota average.
Contaminants & Safety
Disinfection byproducts are the notable finding here. Plymouth's water has TTHMs at 30.7 ppb and HAA5 at 16.8 ppb — both within legal limits, but the EWG health guidelines are far stricter. These byproducts form when chlorine reacts with organic matter during treatment. A whole-house activated carbon filter reduces both chlorine and its byproducts. Want the full picture? Request your utility's annual Consumer Confidence Report.
What's in the Treatment Process
Even though Plymouth draws from groundwater, the treatment process still generates disinfection byproducts: TTHMs at 30.7 ppb and HAA5 at 16.8 ppb. Groundwater typically needs less treatment than surface water, but when organic compounds are present in the aquifer, chlorination creates the same byproducts. All levels are within legal limits, though above the stricter EWG health guidelines.
Chromium-6 is naturally present in Plymouth's aquifer geology at 0.06 ppb — 3x the EWG health guideline. There's no federal legal limit for chromium-6 specifically (only total chromium), which is why EWG tracks it separately. All measurements are within federal legal limits. The EWG guidelines represent a more conservative, health-based standard.
How Hard Water Affects Your Home
At 254 PPM, untreated hard water has measurable effects on household costs and appliance life:
- Water heater inefficiency: Scale insulation forces the heater to work harder (DOE estimates up to 22% more energy for heavily scaled units)
- Soap and detergent: Hard water reduces lathering, requiring significantly more product
- Appliance replacement: Water heaters, dishwashers, and washing machines fail 2-4 years earlier due to scale buildup
- Plumbing maintenance: Scale buildup in pipes reduces flow and requires more frequent service
Note: Impact varies by household size, water usage, and local energy costs. A home water test provides the most accurate assessment for your specific situation.
| Contaminant | Detected | Health Guideline | Legal Limit | Status |
|---|---|---|---|---|
| Hardness (as CaCO₃) | 254 PPM | < 60 PPM | No federal limit | ⚠ Very Hard |
| Total Dissolved Solids | 412 PPM | < 300 PPM | 500 PPM | ⚠ Elevated |
| PFAS (total) | 11.48 ppt | — | No total limit | Detected |
| ↳ PFOA | 0 ppt | 0 ppt | 4 ppt (2024) | ✓ OK |
| ↳ PFOS | 0 ppt | 0 ppt | 4 ppt (2024) | ✓ OK |
| Lead | 2 ppb | 0 ppb (no safe level) | 15 ppb (10 ppb in 2027) | ✓ Low |
| Chlorine / Chloramine | 0.8 mg/L | Taste threshold ~1.0 | 4.0 mg/L | ✓ Normal |
| Nitrate | Not reported | 5 mg/L | 10 mg/L | N/A |
Our Top Picks for Plymouth (254 PPM)
Hard water at 254 PPM causes scale buildup, increased energy use, and premature appliance failure. A softener protects your plumbing and appliances.
How to Test Your Water in Plymouth
With 254 PPM hardness, a quick test strip confirms whether your specific tap matches Plymouth's average before you invest in a softener. Hardness can vary within the same system.
Free option: Request City of Plymouth's annual Consumer Confidence Report for official city-level data.
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About Plymouth's Water Supply
Water Utility: City of Plymouth
Water Source: Groundwater wells (Groundwater)
Population Served: 81,026
Hardness: 254 PPM (14.9 grains per gallon)
Plymouth draws its drinking water from groundwater sources — Groundwater wells. Groundwater typically requires less treatment than surface water because the earth acts as a natural filter. The tradeoff: dissolved minerals from underground rock formations, which is why hardness is elevated here. Calcium and magnesium dissolve into the water as it moves through limestone and dolomite. The system serves 81,000 residents.
Water quality can vary by neighborhood and season. For your exact numbers, request City of Plymouth's Consumer Confidence Report (CCR) or test your own tap.
ZIP Codes Covered by This Report
This water quality data applies to all areas served by City of Plymouth in Plymouth, MN, including ZIP codes:
55305, 55323, 55356, 55391, 55392, 55570, 55571, 55573, 55574, 55576, 55577, 55578, 55579, 55593, 55595, 55596, 55597, 55598, 55599
If your ZIP code is listed above, this report covers your water supply. Water quality may vary slightly by neighborhood.
Water Softener Sizing for Plymouth
At 254 PPM (14.9 GPG), here is how to size a softener for your Plymouth home. Multiply hardness in GPG (14.9) by daily water usage (roughly 50 gallons per person). A family of four uses about 200 gallons/day: 14.9 GPG × 200 gal = 2980 grains/day. Over a 7-day regeneration cycle, that is 20,860 grains - a 32,000-grain softener is the right fit for most Plymouth households.
Compare Plymouth to Other Minnesota Cities
Frequently Asked Questions About Plymouth Water
Is Plymouth tap water safe to drink?
Where does Plymouth's water come from?
Do I need a water softener in Plymouth?
Does Plymouth water damage tankless water heaters?
How much does hard water cost a Plymouth household per year?
What is the hardness of Plymouth water in grains per gallon?
What size water softener do I need for Plymouth?
Salt-based softener or salt-free conditioner for Plymouth?
Data sources: Lead and copper data from EPA Safe Drinking Water Act LCR reporting. Contaminant data from utility-reported testing results. PFAS data from EPA UCMR5 (2023–2025). Hardness from USGS and municipal reports. Data reflects system-level testing results and may not match your specific tap due to neighborhood plumbing, season, or recent utility changes. For your utility's latest results, request their Consumer Confidence Report (CCR). Our methodology. Last updated: 2026-02-24.
What Plymouth Homeowners Actually Buy
Common purchases for homes with 254 PPM water.
Affiliate disclosure: we may earn a commission. Selection based on Plymouth's water data.