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Groundwater vs municipal water — which does your address have, and how to tell
Two homes on the same street can have completely different water sources. One on city water, one on a private well. The data, the testing requirements, and the risk profile are completely different.
Published 2026-04-25 · Last reviewed 2026-04-26 · methodology
Quick how-to-tell
Look at the property tax bill or utility bill. A line item for 'water' from the city = municipal water. No water utility bill = private well.
Look in the basement / crawl space / utility room. Pressure tank (40-80 gallon, often blue) + well pump = private well. Just a meter + main shutoff = municipal.
Ask the seller. The disclosure form in most states asks 'water source: municipal / well / spring / cistern / other'.
Search the EPA SDWIS database — if your address shows up under a Public Water System, you're on municipal water. If not, you're likely on a private well.
If you're on municipal water
Your water utility issues a Consumer Confidence Report (CCR) annually — required by EPA. Search '[your city] consumer confidence report water'.
EPA SDWIS tracks compliance violations. See /topic/water-quality/[zip]/ for last-12-month violations.
Risk profile: known and regulated. The utility is responsible for source-water-to-tap quality. Lead/copper rules apply at the meter.
Cost: typically $30-80/month for a household.
If you're on a private well
EPA does NOT regulate private wells. You are 100% responsible for testing + treatment.
Recommended tests at purchase: total coliform bacteria, nitrate, lead, arsenic, hardness, pH, plus regional contaminants (radon-in-water, PFAS in some regions, uranium in Western mountains).
Annual: bacteria + nitrate. Every 3-5 years: full panel.
Cost: $0/month direct (you own the well + pump). But: well pump replacement $1,500-4,000 every 15-25 years. UV/RO/softener treatment systems $1,000-5,000.
Risk profile: variable. Two adjacent wells can have very different contaminants depending on depth + aquifer.
If the answer is unclear
Some homes have BOTH — municipal for indoor use, well for irrigation. Some have well + cistern fallback. Some are on a 'private community water system' that serves 5-25 homes (regulated lightly under EPA's small-system rules).
Septic + private well combination requires careful siting (well must be uphill / upstream of septic drainfield, minimum 100ft separation typical, varies by state).
If unclear after searching: pull the well log from your state's well-construction database (most states maintain a public registry of well drilling permits).
What zipradar shows
EPA SDWIS data — covers ONLY public water systems (municipal + small-community + non-transient non-community).
If your ZIP shows zero PWS coverage and rural population, assume private wells dominate. See /topic/water-quality/[zip]/.
We do not have parcel-level water-source data. The federation operates at ZIP level; parcel-level water source comes from the seller disclosure or your inspection.
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