Drinking water lead and copper practice questions
20 free practice questions from 40 CFR Part 141 Subpart I. Each answer is explained and linked to the rule it comes from.
Drinking water lead and copper
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Applicability, effective and compliance dates
1. Under the 2024-revised Subpart I, what date does 141.80(a)(3) set as the deadline for community and non-transient non-community water systems to comply with the subpart, apart from the stated exceptions and exemptions?
- A. December 30, 2024
- B. October 16, 2024
- C. November 1, 2027
- D. January 1, 2030
Show answer
Answer: C. November 1, 2027
Systems "must comply with the requirements of this subpart no later than November 1, 2027", except where 141.81, 141.84, 141.85, 141.86 and 141.90 say otherwise or an exemption has been issued. December 30, 2024 is the effective date.
Source: eCFR: 40 CFR 141.80, General requirements and action level (as of Nov 3, 2026)
2. Under 141.80(a)(4)(i) of the 2024-revised Subpart I, which text of 141.80 through 141.91 must community and non-transient non-community systems comply with between October 30, 2024, and November 1, 2027?
- A. The text as codified on July 1, 2020, plus specific newer provisions that the paragraph lists
- B. The full 2024-revised text, with no earlier version applying
- C. Only the text as first published in 1991
- D. No lead and copper requirements apply during that period
Show answer
Answer: A. The text as codified on July 1, 2020, plus specific newer provisions that the paragraph lists
In that period systems "must comply with 40 CFR 141.2, 141.31(d), and 141.80 through 141.91, as codified on July 1, 2020, except systems must also comply with" a list of newer provisions, such as 141.84(a)(1) through (10).
Source: eCFR: 40 CFR 141.80, General requirements and action level (as of Nov 3, 2026)
3. Under the 2024-revised Subpart I (compliance required by November 1, 2027), how does 141.80(b) describe the kind of regulation the subpart is?
- A. A maximum contaminant level rule that sets enforceable MCLs for lead and copper
- B. A secondary standard that is not federally enforceable
- C. A monitoring-only rule with no treatment requirements
- D. A treatment technique rule that includes treatment techniques to control corrosion, treat source water, replace service lines, and provide public education
Show answer
Answer: D. A treatment technique rule that includes treatment techniques to control corrosion, treat source water, replace service lines, and provide public education
141.80(b) states: "The regulations in this subpart constitute a treatment technique rule that includes treatment techniques to control corrosion, treat source water, replace service lines, and provide public education."
Source: eCFR: 40 CFR 141.80, General requirements and action level (as of Nov 3, 2026)
Action levels and the 90th percentile
4. Under the 2024-revised Subpart I (compliance required by November 1, 2027), a system has enough Tier 1 and 2 sites to meet its minimum number of sites. How does 141.80(c)(3)(ii)(A) treat lead or copper results from its Tier 3, 4 or 5 sites in the 90th percentile calculation?
- A. They are included for copper only
- B. They cannot be included in the calculation
- C. They replace the lowest Tier 1 and 2 results
- D. They are averaged with the Tier 1 and 2 results before ranking
Show answer
Answer: B. They cannot be included in the calculation
141.80(c)(3)(ii)(A) states: "Lead or copper sample results from Tier 3, 4, or 5 sites cannot be included in this calculation."
Source: eCFR: 40 CFR 141.80, General requirements and action level (as of Nov 3, 2026)
5. Under the 2024-revised Subpart I (compliance required by November 1, 2027), a system has some Tier 1 and 2 sites but too few to meet its minimum number of sites, so it also uses results from the next highest available tier. After placing the results in ascending order, what does 141.80(c)(3)(iii)(B) require before the results are numbered?
- A. Remove every Tier 1 and 2 result from the list
- B. Average each pair of neighbouring results
- C. Add a zero result for each site it could not sample
- D. Reduce the list to only the samples with the highest concentrations, so the number of results equals the minimum number of sites required by 141.86(c) or (d)
Show answer
Answer: D. Reduce the list to only the samples with the highest concentrations, so the number of results equals the minimum number of sites required by 141.86(c) or (d)
"The water system must reduce this list to only include samples with the highest concentrations such that the number of sample results equals the minimum number of sites required to be sampled by § 141.86(c) or (d), as applicable."
Source: eCFR: 40 CFR 141.80, General requirements and action level (as of Nov 3, 2026)
6. Under the 2024-revised Subpart I (compliance required by November 1, 2027), how does 141.80(c)(3)(i)(D) set the 90th percentile concentration for a system with only Tier 3, 4 and 5 sites that collects five samples per tap sampling period?
- A. The average of the highest and second highest results
- B. The average of all five results
- C. The third (middle) result
- D. The lowest of the five results
Show answer
Answer: A. The average of the highest and second highest results
"For water systems that collect five samples per tap sampling period, the 90th percentile concentration is the average of the highest and second highest concentration".
Source: eCFR: 40 CFR 141.80, General requirements and action level (as of Nov 3, 2026)
7. Under the 2024-revised Subpart I (compliance required by November 1, 2027), for a Tier 1 or 2 site where tiering is based on a lead service line, which lead result does 141.80(c)(3)(ii)(A) put into the 90th percentile calculation?
- A. Only the first-liter result
- B. The average of the first-liter and fifth-liter results
- C. The higher of the first-liter and fifth-liter results
- D. Only the fifth-liter result
Show answer
Answer: C. The higher of the first-liter and fifth-liter results
"For lead, water systems must include the higher of the first-liter and fifth-liter lead sample results at each Tier 1 and 2 site". Only first-liter results are used where "tiering is based on premise plumbing".
Source: eCFR: 40 CFR 141.80, General requirements and action level (as of Nov 3, 2026)
Corrosion control treatment
8. Under the 2024-revised Subpart I (compliance required by November 1, 2027), a large water system (serving more than 50,000 people) without corrosion control treatment has a 90th percentile lead result above 0.005 mg/L but not above the lead action level. What does 141.81(a)(1)(v) require?
- A. Nothing, because the lead action level was not exceeded
- B. Complete steps to study and install OCCT as specified in 141.81(e)
- C. Deliver public education materials only
- D. Replace every service line within 180 days
Show answer
Answer: B. Complete steps to study and install OCCT as specified in 141.81(e)
Large systems without corrosion control treatment whose 90th percentile results "exceed either the lead practical quantitation limit of 0.005 mg/L or the copper action level must complete steps to study and install OCCT, as specified in paragraph (e) of this section."
9. Under the 2024-revised Subpart I (compliance required by November 1, 2027), an individual tap sample site in the site sample plan has a lead result above 0.010 mg/L. What deadline does 141.82(j)(2) set for collecting and analyzing a follow-up lead sample at that site?
- A. Within 30 days of receiving the tap sampling results
- B. Within six months after the end of the tap sampling period
- C. Within 12 months of receiving State notification
- D. By the next standard tap monitoring period
Show answer
Answer: A. Within 30 days of receiving the tap sampling results
"Within 30 days of receiving the tap sampling results, water systems must collect and analyze a follow-up sample for lead at any tap sample site that exceeds 0.010 mg/L."
Source: eCFR: 40 CFR 141.82, Description of corrosion control treatment requirements (as of Nov 3, 2026)
Service line inventory and replacement
10. Under the 2024-revised Subpart I (compliance required by November 1, 2027), what deadline does 141.84(d)(4) set for replacing all lead and galvanized requiring replacement service lines under the system's control, when no shortened or deferred deadline applies?
- A. 5 program years after October 16, 2024
- B. 20 calendar years after December 30, 2024
- C. 15 program years after the compliance date
- D. 10 program years after the compliance date in 141.80(a)(3)
Show answer
Answer: D. 10 program years after the compliance date in 141.80(a)(3)
The deadline "is no later than 10 program years after the compliance date specified in § 141.80(a)(3) unless the system is subject to a different deadline under paragraphs (d)(5)(v) and (vi) of this section."
Source: eCFR: 40 CFR 141.84, Service line inventory and replacement requirements (as of Nov 3, 2026)
11. Under the 2024-revised Subpart I (compliance required by November 1, 2027), where full replacement needs property owner consent, what must a reasonable effort to obtain that consent include under 141.84(d)(3)(i)?
- A. One certified letter to the property owner
- B. At least four attempts, all made by written letter
- C. At least four attempts using at least two different methods of communication
- D. Two attempts using two different methods of communication
Show answer
Answer: C. At least four attempts using at least two different methods of communication
A reasonable effort "must include at least four attempts to engage the property owner using at least two different methods of communication", and "The State may require systems to conduct additional attempts".
Source: eCFR: 40 CFR 141.84, Service line inventory and replacement requirements (as of Nov 3, 2026)
12. Under the 2024-revised Subpart I (compliance required by November 1, 2027), a customer tells the system they intend to replace their portion of a lead service line. What deadline does 141.84(f)(1)(i) set for the system to replace the remaining portion?
- A. No later than 7 days from the customer's replacement
- B. No later than 45 days from the date the customer conducted the partial replacement
- C. No later than 120 days from the customer's notice
- D. No later than two years from the customer's replacement
Show answer
Answer: B. No later than 45 days from the date the customer conducted the partial replacement
The system must replace the remaining portion "at the same time as, or as soon as practicable after, the customer-initiated replacement, but no later than 45 days from the date the customer conducted the partial replacement".
Source: eCFR: 40 CFR 141.84, Service line inventory and replacement requirements (as of Nov 3, 2026)
Public education and notices
13. Under the 2024-revised Subpart I (compliance required by November 1, 2027), what deadline does 141.85(d)(2) set for the consumer notice of individual lead and copper tap results?
- A. One year after the tap sampling period ends
- B. No later than three business days after the water system learns of the tap monitoring results
- C. In the next Consumer Confidence Report
- D. Ten days after the end of the calendar year
Show answer
Answer: B. No later than three business days after the water system learns of the tap monitoring results
"A water system must provide the consumer notice as soon as practicable but no later than three business days after the water system learns of the tap monitoring results."
14. Under the 2024-revised Subpart I (compliance required by November 1, 2027), what triggers the additional filter and outreach requirements of 141.85(j)?
- A. Exceeding the lead action level at least three times in a rolling five-year period
- B. One individual tap sample above 0.010 mg/L
- C. Exceeding the copper action level twice in one year
- D. Missing one annual service line inventory update
Show answer
Answer: A. Exceeding the lead action level at least three times in a rolling five-year period
"A water system that exceeds the lead action level at least three times in a rolling five-year period, based on tap water samples collected in accordance with § 141.86, must conduct the activities in this section."
15. Under the 2024-revised Subpart I (compliance required by November 1, 2027), how does 141.85(b)(4) require a non-transient non-community water system to deliver public education after a lead action level exceedance?
- A. By submitting a press release to media outlets only
- B. By printing a message on each water bill only
- C. By posting it on the system's website only
- D. By posting informational posters in a public place or common area in each building served and distributing pamphlets and/or brochures to each person served
Show answer
Answer: D. By posting informational posters in a public place or common area in each building served and distributing pamphlets and/or brochures to each person served
The system must "Post informational posters on lead in drinking water in a public place or common area in each of the buildings served by the system" and "Distribute informational pamphlets and/or brochures on lead in drinking water to each person served".
Tap sampling
16. Under the 2024-revised Subpart I (compliance required by November 1, 2027), a system lets members of the public collect lead and copper tap samples. What does 141.86(b)(1) bar the sample collection instructions from directing the collector to do?
- A. Collect the sample from an interior kitchen or bathroom sink cold-water tap
- B. Use a wide-mouth, one-liter sample bottle
- C. Remove or clean the aerator or flush taps before the start of the minimum six-hour stagnation period
- D. Let the water stand motionless in the plumbing for at least six hours
Show answer
Answer: C. Remove or clean the aerator or flush taps before the start of the minimum six-hour stagnation period
"Sample collection instructions cannot direct the sample collector to remove or clean the aerator or flush taps prior to the start of the minimum six-hour stagnation period." The same paragraph requires wide-mouth, one-liter bottles and, for residential housing, an interior kitchen or bathroom sink cold-water tap.
Source: eCFR: 40 CFR 141.86, Monitoring requirements for lead and copper in tap water (as of Nov 3, 2026)
17. Under the 2024-revised Subpart I (compliance required by November 1, 2027), sampling sites must be selected from the highest tier available. When does 141.86(a)(4) treat a site as unavailable?
- A. When the site is farther from the treatment plant than the system's average site
- B. When the customer has not answered a single outreach attempt
- C. Whenever the system would rather sample a Tier 5 site
- D. When the customer refuses to participate in sampling, or the system has made at least two outreach attempts at the site without a response
Show answer
Answer: D. When the customer refuses to participate in sampling, or the system has made at least two outreach attempts at the site without a response
"Sites are available unless a customer refuses to participate in sampling or a system has made at least two outreach attempts at a site and has not received a response."
Source: eCFR: 40 CFR 141.86, Monitoring requirements for lead and copper in tap water (as of Nov 3, 2026)
Schools and child care facilities
18. Under the 2024-revised Subpart I (compliance required by November 1, 2027), how many lead samples does 141.92(f)(1) require a community water system to collect per school and per child care facility?
- A. Two per school and five per child care facility
- B. Three per school and three per child care facility
- C. Five per school and two per child care facility
- D. Ten per school and five per child care facility
Show answer
Answer: C. Five per school and two per child care facility
"Community water systems must collect five samples per school and two samples per child care facility at outlets typically used to provide water for human consumption."
Source: eCFR: 40 CFR 141.92, Monitoring for lead in schools and child care facilities (as of Nov 3, 2026)
19. Under the 2024-revised Subpart I (compliance required by November 1, 2027), starting with the compliance date, when does 141.92(e)(1) require a community water system to sample a secondary school it serves?
- A. When requested by the secondary school
- B. Every year at every secondary school
- C. Only when the school is regulated as a public water system
- D. Only after the system exceeds the lead action level
Show answer
Answer: A. When requested by the secondary school
"Starting with the compliance date in § 141.80(a)(3), community water systems must conduct sampling as specified in paragraph (f) of this section when requested by a secondary school."
Source: eCFR: 40 CFR 141.92, Monitoring for lead in schools and child care facilities (as of Nov 3, 2026)
Small system flexibility
20. Under the 2024-revised Subpart I (compliance required by November 1, 2027), which systems may elect the 141.93 compliance flexibility, if approved by the State?
- A. All systems serving 10,000 or fewer persons that exceed the copper action level
- B. Small community water systems serving 3,300 or fewer persons and all non-transient non-community water systems that exceed the lead action level but not the copper action level
- C. Large water systems that exceed the lead practical quantitation limit
- D. Transient non-community water systems that exceed either action level
Show answer
Answer: B. Small community water systems serving 3,300 or fewer persons and all non-transient non-community water systems that exceed the lead action level but not the copper action level
"Small community water systems serving 3,300 or fewer persons and all non-transient non-community water systems that exceed the lead action level, but do not exceed the copper action level, may elect to use this provision" if approved by the State.
Source: eCFR: 40 CFR 141.93, Small water system compliance flexibility (as of Nov 3, 2026)