| #Q001 | monitoring | operational | guidance | Assess Corrosion and Corrective Measures | drinking water | Any size of drinking water distribution system can be subject to corrosion; therefore, it is important for responsible authorities to conduct a monitoring program to assess if and to what degree corrosion may be occurring in a system and to take appropriate corrective measures. | Applicable to any size of drinking water distribution system | high |
| #Q002 | operational | health | recommended | Primary Focus on Lead | drinking water | Although corrosion will affect the release of several contaminants, the primary focus should be lead, since it is the contaminant whose presence is most likely to result in adverse health effects at concentrations typically seen in residences and distributions systems. | When developing and implementing a corrosion control program | high |
| #Q003 | monitoring | operational | recommended | Compliance Sampling and Zonal Coverage | drinking water | Compliance sampling is undertaken by collecting samples representative of the population served in a discretely supplied area (zonal sampling). All zones should be sampled such that the entire distribution system is assessed and, therefore, all problem zones identified across the entire system. | During compliance sampling for corrosion/lead | high |
| #Q004 | operational | health | recommended | Treatment Process Changes and Corrosion | drinking water | Utilities should ensure that changes made to treatment processes or a change in supply do not make the water corrosive towards lead. | When changes are made to treatment processes or water supply | high |
| #Q005 | monitoring | operational | recommended | Sentinel Sites Selection | drinking water | Sentinel sites should focus on areas confirmed to have lead service lines and include zones supplied by potentially corrosive water (e.g., dead ends in a chloraminated system) and consecutive systems (i.e., public water systems whose drinking water supply is from another public water system). | When selecting sentinel sites for lead service line inventories and monitoring | high |
| #Q006 | monitoring | operational | recommended | Tier 2 Sampling Requirement | drinking water | When more than 10% of sites exceed a lead concentration of 0.005 mg/L (system/zonal goal -SG), then Tier 2 sampling should be conducted. | When more than 10% of sites exceed lead concentration of 0.005 mg/L in Tier 1 sampling | high |
| #Q007 | monitoring | operational | guidance | Tier 1 RDT Sampling Procedure | drinking water | A first-draw 1 L sample is taken at the consumer’s cold drinking water tap (without removing the aerator or screen) randomly during the day in each of the residences. There is no stagnation period prescribed and no flushing should occur directly prior to collecting the sample, to better reflect actual consumer use. | Tier 1 sampling using Random Daytime (RDT) protocol | high |
| #Q008 | reporting | health | recommended | Information to Consumers (Below System Goal Exceedance) | drinking water | If less than 10% of sites have lead concentrations above 0.005 mg/L, utilities should provide consumers in dwellings with lead concentrations above 0.005 mg/L with information on methods to reduce their exposure to lead (such as those listed in measure 1 below). | When less than 10% of sites exceed 0.005 mg/L, but some dwellings still exceed this level | high |
| #Q009 | monitoring | operational | recommended | Consumer Follow-up Sampling | drinking water | It is also recommended that utilities conduct follow-up sampling for these sites to assess the effectiveness of the corrective measures undertaken by consumers. | When corrective measures are undertaken by consumers following an exceedance | high |
| #Q010 | corrective_action | health | recommended | Corrective Measures for System Exceedance (RDT) | drinking water | When more than 10% of the sites have a lead concentration greater than 0.005 mg/L (system/zonal goal -SG), it is recommended that utilities take the following measures: 1. Communicate the results of the testing to the consumers and inform them of the appropriate measures that they can take... 2. Initiate a public education program... 3. Conduct additional sampling (as outlined in the Tier 2 sampling protocol) at 10% of the sites sampled in Tier 1... 4. Implement appropriate corrective measures to control corrosion community-wide... 5. Encourage homeowners to periodically clean debris from the screens or aerators... | When more than 10% of sites exceed a lead concentration of 0.005 mg/L | high |
| #Q011 | monitoring | operational | recommended | Tier 2 Minimum Sampling Sites for Small Systems | drinking water | For smaller systems (i.e., serving 500 or fewer people), a minimum of 2 sites should be sampled to provide sufficient lead profile data for the system. | During Tier 2 profile sampling for smaller systems serving 500 or fewer people | high |
| #Q012 | monitoring | operational | guidance | Tier 2 Profile Sampling Method | drinking water | Four consecutive 1 L samples are taken at the consumer’s cold drinking water tap (without removing the aerator or screen) after the water has been stagnant for a defined period of a) 30 min -30 MS or b) 6 h minimum. | When conducting Tier 2 profile sampling | high |
| #Q013 | monitoring | operational | recommended | Follow-up Sampling for CCT Optimization | drinking water | Follow‑up sampling that is intended to demonstrate that lead concentrations throughout the system have been adequately reduced and that corrosion control treatment has been optimized should be conducted until a minimum of 2 consecutive sampling rounds have demonstrated that compliance has been achieved. | When demonstrating CCT optimization | high |
| #Q014 | monitoring | operational | recommended | Annual Compliance Sampling Base Frequency | drinking water | For compliance purposes, lead levels should be monitored at the tap at least once a year to assess whether corrosion is occurring in a water distribution system. | Baseline compliance monitoring | high |
| #Q015 | monitoring | operational | mandatory | Increased Monitoring Frequency Maintenance | drinking water | When a corrosion control program is being implemented, monitoring needs to be more frequent than once per year, the frequency depending on the control measures selected; this increased monitoring frequency must be maintained until the control measures are optimized. | During implementation of a corrosion control program | high |
| #Q016 | monitoring | operational | recommended | System-wide Adjustment Monitoring Frequency | drinking water | When pH and alkalinity adjustments or pH adjustment (if needed) and corrosion inhibitors are used as system-wide corrosion control methods, the water quality should be monitored at least weekly at the entry point to the distribution system and monthly within the distribution system, including at the tap. | When pH, alkalinity adjustments, or corrosion inhibitors are used as system-wide methods | high |
| #Q017 | monitoring | operational | mandatory | Representative Conditions Sampling | drinking water | When implementing a corrosion control program, it must be done so as to capture conditions that are representative of the variations in the water quality (e.g., temperature, pH, alkalinity). | When implementing a corrosion control program | high |
| #Q018 | corrective_action | health | recommended | Post LSL Replacement Flushing and Monitoring | drinking water | When lead service lines are replaced, extensive flushing of the cold water by the consumer should be encouraged, and weekly or biweekly sampling at the tap should be conducted until lead levels stabilize. | Following replacement of lead service lines | high |
| #Q019 | monitoring | operational | recommended | Routine Compliance Sampling Period | drinking water | Routine annual (compliance) sampling should be conducted during the same period every year, since lead leaching as well as the leaching of other materials within the distribution system are influenced by changes in temperature as well as seasonal variations. The warmer season from May to October is chosen... | During routine annual compliance sampling | high |
| #Q020 | monitoring | operational | mandatory | Minimum Annual Samples Per Water Supply Zone | drinking water | A minimum of 20 samples per year is required in a water supply zone (a geographical area within which the quality of drinking water is considered approximately uniform), regardless of sampling methodology. | Applies to water supply zones | high |
| #Q021 | monitoring | operational | recommended | Sample Bottle Type and Aerator Requirement | drinking water | Regardless of the protocol used, all samples should be collected in wide-mouth sample bottles, and without removing the aerator. | During any lead sampling protocol | high |
| #Q022 | monitoring | operational | mandatory | Sample Preservation and Holding Time | drinking water | The samples need to be acidified using a 2% nitric acid solution (by volume) and held for a minimum of 16 h after preservation with nitric acid before analysis. | During sample preparation for lead analysis | high |
| #Q023 | administrative | operational | recommended | Non-Residential Building Sampling Plan | drinking water | A sampling plan should be developed to take into consideration the type of building being sampled and to target priority sites for sampling. It is recommended that a plumbing profile of the building be developed to identify potential sources of lead and areas of stagnation and to assess the potential for lead contamination at each drinking water fountain, cold drinking water outlet or cooking outlet. | When monitoring non-residential/residential buildings | high |
| #Q024 | monitoring | health | recommended | Building Sampling Protocol Compliance | drinking water | Since elevated concentrations of lead can be found in drinking water as a result of leaching from plumbing materials, including fittings and fixtures, within a building, this protocol should be followed by responsible authorities, such as building owners or managers, school boards and employers, as part of the overall management of the health and safety of the occupants... | For overall management of health and safety of occupants of schools, child care centres, and other non-residential buildings | high |
| #Q025 | monitoring | operational | recommended | Tier 1 Building Sampling Execution | drinking water | Tier 1 sampling should be conducted at the locations of the cold drinking water outlets identified in the sampling plan for the non-residential/residential building. In addition, a sample that is representative of the water that is entering the building (water main sample) should be collected at each monitoring event. | During Tier 1 sampling for buildings | high |
| #Q026 | corrective_action | health | recommended | Tier 1 Building Corrective Measures | drinking water | If the lead concentration exceeds 0.005 mg/L (MAC) at any of the monitoring locations, it is recommended that the following measures be undertaken: 1. Educate the occupants... 2. Conduct additional sampling... 3. Implement interim corrective measures immediately to reduce the occupants’ exposure to lead in first-draw water... 4. Where a substantial amount of debris was removed from the aerator or screen, authorities may want to retest... | If lead concentration exceeds 0.005 mg/L at any monitoring location in a building | high |
| #Q027 | corrective_action | health | recommended | Tier 2 Building Corrective Measures | drinking water | When the lead concentration in any of these second samples exceeds 0.005 mg/L, any or a combination of the following corrective measures should be undertaken immediately until a permanent solution can be implemented: routine flushing of the outlet... removing the outlet from service... using certified drinking water treatment devices... providing an alternate water supply | When lead concentration in Tier 2 second sample exceeds 0.005 mg/L in a building | high |
| #Q028 | monitoring | health | mandatory | Priority Building Monitoring Sites | drinking water | Once sampling has been completed at all sites identified in the sampling plan of a non-residential building and a corrosion control program has been implemented effectively, only priority (high-risk) sites need to be monitored annually. | After initial comprehensive sampling and effective CCT implementation in non-residential buildings | high |
| #Q029 | administrative | health | recommended | School and Childcare Sampling Priority | drinking water | The sampling plan for public schools, private schools and child care centres/providers should take into consideration that the types of occupants in these buildings are among the most susceptible to adverse health effects from lead. Consequently, sampling plans for these facilities should prioritize every drinking water fountain and cold water outlet used for drinking or food preparation over infrequently used outlets. | When developing sampling plans for schools and child care facilities | high |
| #Q030 | monitoring | health | recommended | Total Lead Monitoring Frequency for Schools | drinking water | Total lead should be monitored at least once per year. It is recommended that sampling be conducted in either June or October for schools and, when the buildings are fully occupied and functional, between the months of June and October for other building types. | Applicable to schools, childcare centers, and other building types | high |
| #Q031 | corrective_action | health | recommended | MAC Exceedance Investigation | drinking water | An exceedance of the MAC should be investigated and followed by the appropriate corrective actions. | Upon exceedance of the lead maximum acceptable concentration (MAC) | high |
| #Q032 | monitoring | operational | recommended | Parameter Monitoring Duration | drinking water | Water quality parameters such as pH, alkalinity, lead concentration and corrosion inhibitor residuals (where applicable) should be monitored for at least 6 months when pH and alkalinity adjustments are used and for 18 months when corrosion inhibitors are used. | When implementing pH/alkalinity adjustments or corrosion inhibitors | high |
| #Q033 | administrative | operational | recommended | Monitoring Site Inventory Development | drinking water | It is important that responsible authorities develop an inventory of monitoring sites where lead materials are likely to be present. | For corrosion control program implementation and site selection | high |
| #Q034 | operational | health | mandatory | Prevention of Aggressive Water | drinking water | corrosion control programs need to ensure that the delivered water is not aggressive for all components of the distribution system and the plumbing system. | General corrosion control program management | high |
| #Q035 | monitoring | operational | mandatory | Silicate Use Safety Protocols | drinking water | the use of sodium silicates necessitates adherence to occupational health and safety protocols | When using sodium silicates for corrosion control treatment in small systems | high |
| #Q036 | monitoring | health | recommended | Initial Building Sampling Scope | drinking water | Every priority site identified in the sampling plan should be sampled in the first year. | Initial implementation of a building sampling plan | high |
| #Q037 | monitoring | operational | guidance | Sampling Protocol Suitability | drinking water | it is important that the protocol selected be appropriate to meet the desired objective and type of dwelling. | When selecting a lead sampling protocol for a monitoring program | high |
| #Q038 | monitoring | operational | guidance | Secondary Metal Analysis Guidance | drinking water | Analysis of other metals (e.g., Cu, Cd, Fe, Mn) in the collected samples can help in identifying source of lead (e.g., brass, galvanized steel) or reveal interferences that impair corrosion control treatment (i.e., orthophosphate) that should be addressed. | During investigative Tier 2 sampling | high |
| #Q039 | monitoring | operational | mandatory | Tier 2 Sample Selection Procedure | drinking water | The analyses for the second tier are then done only on the appropriate samples, based on the results of the Tier 1 samples. | When samples for both tiers are collected during the same site visit | high |
| #Q040 | reporting | operational | unknown | Lead Concentration Averaging Method | drinking water | Where two 125 mL volumes are collected, the concentration of lead is determined by averaging the results from both samples. | When building samples are collected in dual 125 mL volumes | high |
| #Q041 | administrative | health | recommended | Stakeholder Collaboration in Sampling Design | drinking water | Utilities, building owners and other responsible authorities (e.g., school boards) should work collaboratively to ensure that sampling programs are designed to be protective of the health of the occupants, including high-risk populations such as young children and pregnant people. | When designing building-specific sampling programs | high |
| #Q042 | monitoring | operational | recommended | Verification of Flushing Program Effectiveness | drinking water | When routine flushing programs are implemented as a corrective measure, sampling should be conducted so that it can be demonstrated that flushing is effective at reducing lead concentrations throughout the period of the day when the building is occupied. | When routine flushing is utilized as a lead mitigation strategy | high |
| #Q043 | monitoring | health | recommended | Post-Outlet Replacement Monitoring | drinking water | Similarly, when outlets are replaced, sampling should be conducted up to 3 months following replacement to ensure that lead levels have been adequately lowered. | Following the replacement of faucets, fountains, or fittings | high |
| #Q044 | operational | operational | recommended | Basis of Corrosion Control Program | drinking water | A corrosion control program for a drinking water system should be based on the levels of specific contaminants at the consumer’s tap. | When establishing a corrosion control program | high |
| #Q045 | monitoring | operational | guidance | Authority Retesting After Debris Removal | drinking water | If a substantial amount of debris is removed from the aerator or screen, authorities may want to retest the water from these outlets following the same protocol. | Following debris removal from screens or aerators by homeowners or authorities | high |
| #Q046 | monitoring | operational | recommended | Monitoring for Water Quality and Process Changes | drinking water | More frequent monitoring is recommended when changes in the water quality in the distribution system (e.g., nitrification) are noted or when there are changes made to the treatment process (including changes in the disinfectant, oxidant or coagulant) or source that would alter water quality parameters affecting corrosion, such as pH and alkalinity. | When water quality changes are noted or treatment processes are modified | high |
| #Q047 | monitoring | operational | recommended | Implementation Phase Indicator Monitoring | drinking water | During the implementation stage, copper, iron, disinfectant residuals and microbial indicators should also be monitored within the distribution system. | During the implementation stage of a corrosion control program | high |
| #Q048 | monitoring | operational | recommended | Sentinel Site Count and Monitoring Frequency | drinking water | Generally, a minimum of 6 sentinel sites is recommended and weekly sampling is recommended when assessing corrosion control. | When establishing sentinel sites and frequency for corrosion control assessment | high |
| #Q049 | monitoring | operational | mandatory | On-site pH Measurement for Small Systems | drinking water | Measure pH on-site for accuracy | During water quality characterization for small systems | high |
| #Q050 | monitoring | operational | recommended | Localized Building Changes Monitoring Trigger | drinking water | Localized changes in the distribution system, such as changes in the piping, faucets or fittings used as a result of repairs or new construction as well as changes in water use patterns, should also trigger additional monitoring. | When localized repairs, construction, or water use changes occur in buildings | high |
| #Q051 | monitoring | operational | recommended | Water Main Sample Collection Procedure | drinking water | Water main samples should be collected from a drinking water faucet in close proximity to the service line following a period of approximately 5 min of flushing (longer flushing may be necessary to ensure that the sample is representative of water that has been flowing in the main). | When collecting a sample representative of water entering a non-residential/residential building | high |
| #Q052 | monitoring | health | recommended | 5-Year Comprehensive Building Testing Cycle | drinking water | The remaining sites in the plan should then be sampled in subsequent years so that ultimately all sites identified in the sampling plan have been tested within a 5-year period. | Applicable to schools, childcare facilities, and other non-residential/residential buildings where not all sites are sampled in the first year | high |
| #Q053 | administrative | operational | mandatory | Small System Monitoring Site Reduction Restriction | drinking water | For smaller systems, a reduced number of monitoring sites is not possible, since a minimum number of sites is required to adequately characterize lead concentrations in the system. | When considering reduced annual monitoring for small water systems | high |
| #Q054 | monitoring | operational | mandatory | Seasonal Consideration for Short-Term CCT Evaluation | drinking water | If corrosion control is carried out over a period of less than a year, then it would be necessary to demonstrate that seasonality issues (e.g., temperature, colour, pH, alkalinity) have been taken into account in analyzing the effectiveness of corrosion control measures. | When corrosion control evaluation is conducted over a period of less than a year | high |
| #Q055 | monitoring | operational | recommended | Online Real-time Monitoring Consideration | drinking water | Online, real time monitoring of all process control parameters should be considered for capturing water quality variability. | When monitoring process control parameters for corrosion control program implementation | high |
| #Q056 | monitoring | operational | mandatory | LSL Detection Screening Threshold Determination | drinking water | Must determine screening threshold for lead | When using simpler sampling methods (like flushed sampling) to detect lead service lines in small systems | high |
| #Q057 | monitoring | operational | mandatory | Building Tier 2 Sampling Protocol | drinking water | At those cold drinking water outlets (without removing the aerator or screen) with lead concentrations that exceeded 0.005 mg/L for Tier 1, a minimum of 2 consecutive 125 mL samples are taken after the water has been fully flushed for 5 min and then left to stagnate for 30 min. | During Tier 2 investigation of outlets in non-residential/residential buildings that exceeded the MAC in Tier 1 | high |
| #Q058 | monitoring | operational | recommended | Multi-Dwelling LSL Priority | drinking water | When sampling multi-dwelling buildings, priority should be given to sites suspected or known to have full or partial lead service lines. | When selecting sampling sites in multi-dwelling buildings (more than 6 residences) | high |
| #Q059 | operational | treatment | guidance | Small System Material Replacement Strategy | drinking water | it may be more reasonable for small systems to consider materials replacement rather than corrosion control treatment (CCT). | For small systems evaluating corrosion control options | high |
| #Q060 | corrective_action | health | recommended | Particulate Lead Contribution Investigation | drinking water | If results of the retesting show lead concentrations below 0.005 mg/L, utilities should investigate whether particulate lead may be contributing significantly to elevated lead levels and whether regular cleaning of the aerator or screen is an appropriate corrective measure. | Following retesting of outlets where lead levels dropped below MAC after aerator/screen cleaning | high |