The short answer: your water quality report is the Consumer Confidence Report, or CCR, that every community water system in the U.S. must deliver to its customers by July 1 each year. It covers the previous calendar year: where the water comes from, which regulated contaminants were detected and at what levels, and any violations. Find it on your utility's website, through EPA's CCR search, or by calling the number on your bill; read it one table column at a time. It describes the water system, not the pipes in your house. A private well gets no report at all.
That last point is why a site about private wells covers city reports: the CCR is a good template for what a well owner has to do alone. And the rules change on January 1, 2027, when larger systems start sending the report twice a year. Dates below come from the regulation itself (40 CFR Part 141, Subpart O, eCFR current to November 12, 2026).
What a water quality report is, and who has to send one
EPA calls the CCR "also known as an annual drinking water quality report" and says "Reports must be sent by your water supplier each year by July 1" (EPA, CCR information for consumers, updated November 10, 2026). The federal rule says the subpart "applies only to community water systems" (40 CFR 141.151(b)). EPA defines a community water system as one that "supplies water to the same population year-round" (EPA, Information about public water systems, updated March 16, 2026).
So the duty is narrower than people assume. A school or factory that supplies its own water to at least 25 of the same people for six months a year is a non-transient non-community system; a campground or gas station is a transient one. Both are public water systems, but neither has to publish a CCR. A private household well gets none.
Nor is the typical system a city utility. EPA's federal inventory (SDWIS, 2026, quarter 3) lists 49,342 active community water systems, and more than half serve 500 people or fewer.
Show the numbers
| Item | Value | Note |
|---|---|---|
| 500 people or fewer | 26,488 systems | 53.7% of systems |
| 501 to 3,300 people | 13,257 systems | 26.9% |
| 3,301 to 10,000 people | 4,996 systems | 10.1% |
| 10,001 to 100,000 people | 4,114 systems | 8.3% |
| More than 100,000 people | 487 systems | 1.0% |
Every active community water system in EPA's federal database (49,342), grouped by the population each system reports. Only community systems must send a water quality report. Private wells are not in this database. Source: U.S. EPA, SDWIS Federal Reporting Services, Water System Summary (submission year 2026, quarter 3; community water systems; active), downloaded and grouped by WaterListed using EPA's Pop Cat 5 size bands, accessed 2026-11-14.
Count people instead, and the picture flips. The 487 systems serving more than 100,000 people report almost half of everyone on community water. The five largest (New York City, Los Angeles, Houston, Chicago and San Antonio) report about 20.5 million people between them, more than four times the 4.5 million served by all 26,488 of the smallest systems combined.
Show the numbers
| Item | Value | Note |
|---|---|---|
| 500 people or fewer | 1.4 % of reported population | 4.5 million people |
| 501 to 3,300 people | 5.8 % of reported population | 19.1 million |
| 3,301 to 10,000 people | 8.8 % of reported population | 29.4 million |
| 10,001 to 100,000 people | 35.9 % of reported population | 119.1 million |
| More than 100,000 people | 48.2 % of reported population | 159.9 million |
Same 49,342 systems. Shares of the 331.9 million people the systems report serving; system-reported counts can overlap, so read the shares as approximate. The 1% of systems serving more than 100,000 people account for almost half. Source: U.S. EPA, SDWIS Federal Reporting Services, Water System Summary (submission year 2026, quarter 3; community water systems; active), Population Served Count summed by WaterListed using EPA's Pop Cat 5 size bands, accessed 2026-11-14.
Why that matters: a search for "NYC tap water quality" or "San Diego water quality report" finds a big utility's designed report online. Where a state has waived direct delivery, a system serving 500 or fewer people may instead post a notice that the report "is available upon request" (40 CFR 141.155(g)(2)), so a search for a small subdivision's report may find nothing. Both are legal. By our count, more than 3,800 systems in EPA's list have "mobile home," "MHP," "trailer" or "manufactured home" in their names, and 421 have "apartment." If you live in one, the park or the landlord is your water system.
How to find your water quality report
Work down this list until one step works.
- Find the system's name on your water bill. No bill? See the renters section below.
- Check the utility's website. Today a community system serving 100,000 or more people must post its current report on a public website. From 2027 the threshold drops to 50,000 people, and web reports must stay up for at least 3 years (40 CFR 141.155(f), (a)(4)). In EPA's inventory, 488 community systems report serving 100,000 or more people and 1,087 serve 50,000 or more.
- Use EPA's CCR search. EPA's Find Your Local CCR tool searches by state, water system name, and city, town or county. There is no ZIP code field, and the page warns: "CCRs for all water systems may not be available."
- Not sure which system serves your address? EPA's service area map links each area to a federal water system ID and covers systems serving roughly 99% of the people on community water. EPA cautions that its modeled areas "are estimates" and that "Local government is typically the most accurate source of information to determine whether a particular water system serves a property" (EPA, Public water system service areas, updated August 10, 2026).
- Ask. Every community system "must make its reports available to the public upon request" (40 CFR 141.155(e)), and each one has to file a copy with the state drinking water program (141.155(c)). EPA's Drinking Water Data and Tools page links to state drinking water databases. EPA's Safe Drinking Water Hotline is 800-426-4791.
"Water quality report by ZIP code"
Third-party databases will turn a ZIP code into a water system. Treat the answer as a lead. A ZIP code is a mail route, not a water system boundary: one ZIP can hold a city utility, several small systems and homes on private wells, and EPA's own map warns that areas served by "private wells or unmapped public water systems" are not shown. Confirm the system name on your bill or with the local government, then pull that system's report. If the house is on a well, a ZIP is useful for a different question, what to test for. Our ZIP checker answers that from state and federal data and lists the nearest certified labs.
Renters, condos, mobile home parks, and water you don't pay for
The rule's delivery duty runs to customers, which it defines as "billing units or service connections to which water is delivered" (40 CFR 141.151(c)). If you don't pay a water bill, you are probably not a customer in that sense. The system must still "make a good faith effort to reach consumers who do not get water bills," which EPA says should be tailored to people "such as renters or workers" (141.155(b)). From 2027 every report summary must also ask readers to "share this information with anyone who drinks this water" (141.156(f)).
EPA's service area page puts it simply: "If you are renting and not paying a water bill, your landlord should be able to direct you." If the park, complex or homeowners' association runs its own well and serves residents year-round, it may itself be the community water system that owes you the report.
Anatomy of a CCR table
Most of a CCR is required wording: water source, definitions, health statements. The part that changes each year is the table of detected contaminants, which must be "clear and understandable for consumers" (40 CFR 141.153(d)). Here is a typical one, every column numbered.
Sample CCR · Detected regulated contaminants · data year 2026
| [1] Contaminant (unit) | [2] MCLG | [3] MCL or AL | [4] Level detected | [5] Range | [6] Violation? | [7] Likely source |
|---|---|---|---|---|---|---|
| A. Nitrate, as nitrogen (ppm) | 10 | MCL 10 | 6.2 | 1.1 to 6.2 | No | Runoff from fertilizer use; leaching from septic tanks, sewage; erosion of natural deposits |
| B. Arsenic (ppb) | 0 | MCL 10 | 6 | 2 to 6 | No | Erosion of natural deposits; runoff from orchards; runoff from glass and electronics production wastes |
| C. TTHMs, total trihalomethanes (ppb) | N/A | MCL 80 | 61 (highest locational running annual average) | 24 to 92 (single samples) | No | By-product of drinking water disinfection |
| D. Copper (ppm), tap samples | 1.3 | AL 1.3 | 0.31 (90th percentile); 0 of 60 sites above AL | 0.02 to 0.88 | No | Corrosion of household plumbing systems; erosion of natural deposits |
| E. Lead (ppb), tap samples | 0 | AL 15 | 8 (90th percentile); 2 of 60 sites above AL | Not detected to 22 | No | Corrosion of household plumbing systems; erosion of natural deposits |
- Contaminant and unit. The MCL must be shown "as a number equal to or greater than 1.0," so Appendix A converts arsenic's 0.010 mg/L into 10 ppb (multiply by 1,000). One ppm is one milligram per liter; one ppb is one microgram per liter.
- MCLG, the goal: "The level of a contaminant in drinking water below which there is no known or expected risk to health." It is zero for lead and arsenic, which is why the goal and the limit differ.
- MCL or AL, the enforceable line. An MCL is "The highest level of a contaminant that is allowed in drinking water." Lead and copper have no MCL; they have an action level, "The concentration of a contaminant which, if exceeded, triggers treatment or other requirements which a water system must follow."
- Level detected. Usually not an average of all your samples. For a contaminant checked once a year or less often, it is "The highest detected level at any sampling point." For TTHMs it is the highest locational running annual average. For lead and copper it is the 90th percentile of the latest round of tap samples plus "the number of sampling sites exceeding the action level."
- Range of detected levels. For TTHMs the rule asks for "the range of individual sample results," which is why row C can show a 92 next to a limit of 80 without a violation: compliance is judged on the running average, not single samples.
- Violation. The table "must clearly identify any data indicating violations," and the report must explain the length of the violation, the potential health effects in Appendix A wording, and what the system did about it.
- Likely source, "to the best of the operator's knowledge." If the operator lacks specific information, the report must list typical sources from Appendix A. So this column can be boilerplate, not a finding about your watershed.
Notes: 40 CFR 141.153(c) and (d)(4).
Worked example: reading the lead row
Row E says lead was 8 ppb at the 90th percentile, 2 of 60 sites were above the action level, and the highest result was 22 ppb.
Why 60 sites. Under the lead and copper rule that applies until November 1, 2027, a system serving 10,001 to 100,000 people samples at least 60 sites in a standard monitoring round, or 30 on reduced monitoring (40 CFR 141.86(c), 2020 text). The samples are "first-draw" water that "stood motionless in the plumbing system of each sampling site for at least six hours," collected at sites drawn from a pool of "targeted sampling sites" (141.86(a) and (b)).
Why 8 ppb. The system ranks all 60 results from lowest to highest, multiplies 60 by 0.9, and reports the 54th result (40 CFR 141.80(c)(3), 2020 text). The current action level is exceeded if the 90th percentile "is greater than 0.015 mg/L," which is 15 ppb. At 8 ppb, there is no exceedance, so "No" in the violation column is correct.
Why it still matters. Two homes in the sample were above 15 ppb and one reached 22. The report shows the system met the rule. It can't tell you whether your house is like the 58 sites at or below 15 ppb or the 2 above it. The lead statement every report carries already admits it: the utility "cannot control the variety of materials used in plumbing components in your home" (40 CFR 141.154(d), 2023 text). The version that applies from November 1, 2027 goes further: "Because lead levels may vary over time, lead exposure is possible even when your tap sampling results do not detect lead at one point in time" (141.154(d), current text). EPA's lead page says lead pipes are more likely in "homes built before 1986," that "testing is the only sure way" to know, and: "Contact your water utility to have your water tested" (EPA, Basic information about lead in drinking water, updated June 18, 2026).
What changes in 2027. The Lead and Copper Rule Improvements require compliance "no later than November 1, 2027." From then the action level is exceeded at a 90th percentile "greater than 0.010 mg/L," or 10 ppb, and at sites with lead service lines the system counts "the higher of the first-liter and fifth-liter lead sample results" (40 CFR 141.80, current text). Our example system, at 8 ppb, stays under the new level; one at 12 ppb would not. The lead explainer covers health goals and testing.
The other rows, briefly
- Nitrate at 6.2 ppm triggers a warning paragraph. A system that detects nitrate "above 5 mg/l, but below the MCL" must add a statement about infants. In the wording the rule suggests from 2027: if you are caring for an infant and using tap water to prepare formula, "you may want to use alternate sources of water or ask for advice from your health care provider" (40 CFR 141.154(c)). More in our nitrate explainer.
- Arsenic at 6 ppb triggers one too. Detection "above 0.005 mg/L and up to and including 0.010 mg/L" requires an arsenic statement; the 2027 model wording includes: "EPA's MCL for arsenic balances the scientific community's understanding of arsenic-related health effects and the cost of removing arsenic from drinking water" (141.154(b)). See arsenic.
- Copper follows lead's method against a 1.3 ppm action level. See copper.
What your water quality report doesn't tell you
A CCR is accurate within narrow edges. Know them.
- Your own plumbing. Lead and copper come mostly from service lines and household plumbing; the system cannot control the plumbing inside your home (row E).
- The present. A report delivered by July 1 contains "data collected during the previous calendar year, or the most recent calendar year before the previous calendar year" (40 CFR 141.152(b)). If a contaminant is monitored less than once a year, the report gives "the date and results of the most recent sampling," and "No data older than 5 years need be included" (141.153(d)(3)(i)). Urgent problems travel faster: an E. coli or nitrate MCL violation requires public notice "as soon as practical but no later than 24 hours" (40 CFR 141.202).
- Every result. You get the highest level and a range, or a 90th percentile, not each sample.
- Contaminants nobody had to test. The table covers contaminants "subject to mandatory monitoring"; unregulated ones appear only when federal monitoring was required, as "the average and range" (141.153(d)(1), (d)(7)). For other results, EPA only "strongly encourages" reporting those that may indicate a health concern (141.153(e)(3)).
- Missing data. A missed sample produces no number. The report must still note any violation of "Monitoring and reporting of compliance data" (141.153(f)(1)), so read that section, not just the table.
- A private well. Nothing in Subpart O reaches a household well.
How common are monitoring gaps? EPA's 2024 snapshot covers all public water systems.
Show the numbers
| Item | Value | Note |
|---|---|---|
| Active public water systems | 147,252 systems | |
| No reported violation | 101,272 systems | "Nearly sixty-nine percent" |
| At least one violation of any kind | 45,980 systems | 31% |
| Missed a monitoring or reporting requirement | 34,398 systems | 23% |
| At least one health-based violation | 10,769 systems | 7% |
| Enforcement priority in at least one quarter | 5,582 systems | 3.8%; 92% of these serve 3,300 or fewer people |
| Health-based: no lead service line inventory by Oct 16, 2024 | 3,902 systems | about 2.7% |
All types of public water systems, calendar year 2024. Categories overlap: one system can have several kinds of violation. A monitoring or reporting violation means required data were late or missing, so a report may have gaps. Source: U.S. EPA, Providing Safe Drinking Water in America: National Public Water Systems Compliance Report, 2024 snapshot (updated June 24, 2026), accessed 2026-11-14.
In 2024, "Twenty-three percent (34,398) of the active PWSs failed to meet at least one monitoring or reporting requirement by not providing timely and complete information on contaminants present in their water," and seven percent had at least one health-based violation (EPA, National Public Water Systems Compliance Report, updated June 24, 2026). That 7% includes 3,902 systems that missed the October 16, 2024 deadline for a lead service line inventory. Of 5,582 enforcement priorities, "The majority (5,152 or 92%)" served 3,300 people or fewer.
Where the PFAS and lead rules stand (November 2026)
On PFAS, EPA's 2024 final rule says systems must "provide the public with information on the levels of these PFAS in their drinking water beginning in 2027," and have until 2029 to fix levels above the limits. EPA's page then says: "On May 18, 2026, EPA announced two proposed rules related to PFAS in drinking water for public comment." One would let systems "request two additional years - to 2031" for PFOA and PFOS; the other would rescind the limits for PFHxS, PFNA, HFPO-DA (GenX) and the Hazard Index mixture (EPA, PFAS drinking water regulation, updated May 18, 2026; rescission notice: 91 FR 29413, May 20, 2026, "Notice of proposed rule"). Both are proposals. As of November 14, 2026, the eCFR (current to November 12) still carries all six 2024 PFAS limits, including the Hazard Index. Our PFAS page tracks this. On lead, the November 1, 2027 date and 10 ppb action level above are the current codified text.
The 2027 CCR rule: what changes
EPA announced the final CCR Rule Revisions on May 15, 2024 (EPA, CCR rule revisions, updated November 10, 2026). The switch-over: "Beginning January 1, 2027, community water systems must comply with 40 CFR 141.151 through 141.156" in the 2024 text (40 CFR 141.152(a)). Neither the eCFR nor EPA's page shows any proposal to delay it as of November 14, 2026.
| Topic | Through December 31, 2026 | From January 1, 2027 | Rule |
|---|---|---|---|
| How often | Once a year, by July 1 | By July 1 for all; systems serving 10,000 or more people also deliver "biannually, or twice per calendar year, by December 31" | 141.155(j) |
| First page | No required summary | A summary "displayed prominently at the beginning," with violations, contact details and how to get a paper copy; "should be written in plain language and may use infographics" | 141.156 |
| Delivery | "mail or otherwise directly deliver" | Paper, a mailed notice with a direct link, an emailed link or copy, or another state-approved method; paper on request | 141.155(a) |
| Posted online | Required for systems serving 100,000 or more | Required for 50,000 or more; web reports kept up at least 3 years | 141.155(f), (a)(4) |
| Copy and certification to the state | Copy by the delivery date; certification "within 3 months" | Copy and certification "No later than 10 days after" the delivery deadline | 141.155(c) |
| Translation | Translation help where the state finds a "large proportion" of non-English speakers | Stricter: the report must explain its importance in those languages and either say where to get a translated copy or help, or be translated; the summary must say where to get it; plus a language-assistance plan for systems serving 100,000 or more | 141.153(h)(3), 141.156(c)(2), 141.155(i) |
| Lead | Lead statement; service line inventory statement | Adds "a plainly worded explanation of the corrosion control efforts"; from November 1, 2027, access to full lead tap data, a rewritten lead statement and school and child care sampling | 141.153(h)(8), 141.154(d) |
| Small systems with a delivery waiver | Publish in local newspapers | Local newspapers "or on one or more local online news sites" | 141.155(g) |
Source: 40 CFR 141 Subpart O as codified July 1, 2023 (eCFR point-in-time) and current text, eCFR current to November 12, 2026.
The second report is not always new content. EPA's Q&A says systems with a violation, a lead action level exceedance or new unregulated-contaminant results between January and June "will include a 6-month update along with the previously delivered annual report. Other systems will deliver the first report again to ensure consumers receive it" (EPA, Questions & Answers: CCR Rule Revisions). One wording gap: EPA's web page says "systems serving over 10,000 customers," while the regulation says "serving 10,000 or more persons." Go by the regulation. In EPA's inventory, 4,613 community systems serve 10,000 or more people: 9.3% of systems, but 84.1% of the reported population. Most people on city water will get two reports a year; most systems will still send one.
The CCR calendar
The first report year under the revised rule, from 40 CFR 141.152, 141.155 and 141.80 (current text):
CCR calendar · 2026 data, 2027 reports
| Date | What happens | Which systems | Rule |
|---|---|---|---|
| Jan 1 to Dec 31, 2026 | The data year. Samples taken now fill the July 2027 report | All community systems | 141.152(b) |
| Apr 1, 2027 | A system that sells water to another community system sends the buyer its report data | Wholesalers | 141.152(d)(1) |
| Jul 1, 2027 | Report reaches customers. First report under the revised rule; language-assistance plan goes to the state with it | All community systems; plan: 100,000 or more people | 141.155(j)(1), (i) |
| Jul 11, 2027 | Copy of the report and a certification of delivery due at the state (10 days after the deadline) | All community systems | 141.155(c) |
| Oct 1, 2027 | Wholesalers send six-month information to buyers that report twice a year | Wholesalers | 141.152(d)(3) |
| Nov 1, 2027 | Lead and Copper Rule Improvements compliance date; lead action level becomes 10 ppb | Community and non-transient non-community systems | 141.80(a)(3), (c)(1) |
| Dec 31, 2027 | Second delivery, with a six-month update if there was a violation, a lead or copper action level exceedance or new unregulated-contaminant results from January to June | 10,000 or more people | 141.155(j)(2), (3) |
On a private well? There is no report, so you write your own
EPA is plain about it: water from private domestic wells is "not regulated by the Federal Government under the Safe Drinking Water Act nor by most state governments and laws," and "Private well owners are responsible for delivering safe drinking water to their households." That covers "over 43 million" people (EPA, Private drinking water wells, updated November 2, 2026). CDC: "As a water well owner, you are responsible for testing your well to make sure the water is safe to drink" (CDC, Guidelines for testing well water, July 1, 2024).
A neighbor's utility report describes a different source, after treatment. The useful move is to copy the CCR's structure and fill it in yourself:
| What a CCR gives a city customer | The private-well version | Where to start |
|---|---|---|
| Testing on a legal schedule | CDC: "At least once every year" for total coliforms, pH, total dissolved solids and nitrates, plus local concerns; again after floods, repairs, a change in taste, color or smell, a pregnancy or a child moving in | How to test well water |
| A certified laboratory | CDC: "Use a state-certified laboratory to test your water" | Certified lab finder |
| A list of local contaminants of concern | Your state and county data on arsenic, uranium, radon, nitrate and others | ZIP checker |
| The detected-contaminants table | Your lab report, read against the same federal numbers as a yardstick (they don't bind a private well) | Read a well water test report |
| Lead tap sampling | A first-draw lead test at your own kitchen tap | Lead |
| Bacteria monitoring | A total coliform test each year (CDC); you can also test for E. coli | Coliform bacteria |
| A violation notice | None. You read the result and decide what to do, with your health department | Results checker |
Comparing a house on a well with one on city water? Our well water vs. city water guide sets the testing schedules side by side. If a result worries you because of a pregnancy, an infant or an illness, ask your doctor or the local health department; the federal limits here apply to public water systems.
Next step
On city water: get this year's report and read the lead row the way we read row E. If your house is older or has a lead service line, ask the utility for a tap test. On a well, you are the utility: book this year's test with a state-certified lab through the lab finder and keep every lab report in one folder. That folder is your water quality report.
Questions people ask
What is a consumer confidence report?
When do water quality reports come out each year?
Can I get a water quality report by ZIP code?
Does a water quality report cover my private well?
What does the 90th percentile lead number in my report mean?
Why does my report show last year's data?
My report lists a violation. Is my water unsafe?
- eCFR, 40 CFR Part 141 Subpart O, Consumer Confidence Reports, ยงยง 141.151-141.156 and Appendix A (current text, eCFR up to date as of November 12, 2026) (accessed 2026-11-14)
- eCFR, 40 CFR Part 141 Subpart O as codified July 1, 2023 (point-in-time; the text systems follow through December 31, 2026) (accessed 2026-11-14)
- eCFR, 40 CFR Part 141 Subpart O as codified July 1, 2024 (point-in-time; the text systems follow from January 1, 2027) (accessed 2026-11-14)
- eCFR, 40 CFR 141.80, General requirements and action level (current text, Lead and Copper Rule Improvements) (accessed 2026-11-14)
- eCFR, 40 CFR 141.80 as codified July 1, 2020 (lead action level 0.015 mg/L; 90th percentile method) (accessed 2026-11-14)
- eCFR, 40 CFR 141.86 as codified July 1, 2020 (lead and copper tap sampling sites and first-draw samples) (accessed 2026-11-14)
- eCFR, 40 CFR 141.202, Tier 1 Public Notice (current text) (accessed 2026-11-14)
- eCFR, 40 CFR 141.62 (nitrate MCL 10 as nitrogen), 141.64 (TTHM MCL 0.080 mg/L) and 141.61 (PFAS MCLs and Hazard Index) (current text) (accessed 2026-11-14)
- U.S. EPA, CCR Information for Consumers (updated November 10, 2026) (accessed 2026-11-14)
- U.S. EPA, Consumer Confidence Report Rule Revisions (updated November 10, 2026) (accessed 2026-11-14)
- U.S. EPA, Questions & Answers: Consumer Confidence Report Rule Revisions (PDF, December 2024 upload) (accessed 2026-11-14)
- U.S. EPA, Find Your Local CCR (CCR search tool) (accessed 2026-11-14)
- U.S. EPA, Information about Public Water Systems (updated March 16, 2026) (accessed 2026-11-14)
- U.S. EPA, Public Water System Service Areas (updated August 10, 2026) (accessed 2026-11-14)
- U.S. EPA, Drinking Water Data and Tools (updated November 2, 2026) (accessed 2026-11-14)
- U.S. EPA, SDWIS Federal Reporting Services, Water System Summary (submission year 2026, quarter 3; community water systems; active), downloaded as CSV (accessed 2026-11-14)
- U.S. EPA, Providing Safe Drinking Water in America: National Public Water Systems Compliance Report, 2024 snapshot (updated June 24, 2026) (accessed 2026-11-14)
- U.S. EPA, Per- and Polyfluoroalkyl Substances (PFAS): drinking water regulation (updated May 18, 2026) (accessed 2026-11-14)
- Federal Register, 91 FR 29413 (May 20, 2026), Rescission of Regulatory Determinations and Removal of Related Provisions for Four PFAS Substances, Notice of proposed rule (govinfo) (accessed 2026-11-14)
- U.S. EPA, Basic Information about Lead in Drinking Water (updated June 18, 2026) (accessed 2026-11-14)
- U.S. EPA, Private Drinking Water Wells (updated November 2, 2026) (accessed 2026-11-14)
- CDC, Guidelines for Testing Well Water (July 1, 2024) (accessed 2026-11-14)