| Req ID | Category | Intent | Legal Status | Name | Subdomain(s) | Context | Conditions | Confidence |
|---|---|---|---|---|---|---|---|---|
| #Q001 | operational | treatment | mandatory | Optimize Turbidity Reduction | drinking water | Utilities need to identify the main factors that affect turbidity reduction for the filtration technology that is being used and optimize the process. | high | |
| #Q002 | monitoring | operational | recommended | Continuous Turbidity Monitoring - Conventional/Direct | drinking water | All conventional and direct filtration plants should conduct continuous turbidity monitoring of filter effluent as an indicator of the performance of the treatment process. | high | |
| #Q003 | monitoring | operational | mandatory | Individual and Combined Filter Monitoring | drinking water | Continuous monitoring of the effluent turbidity from each individual filter as well as continuous monitoring of the combined filtered water turbidity from all filters are considered operational necessities in order to provide adequate performance data | high | |
| #Q004 | design | treatment | recommended | Filter-to-Waste Design - Conventional/Direct | drinking water | In general, all filters should be designed so that the filtered water produced immediately after filter backwashing is directed into a waste stream ("filter-to-waste"). | high | |
| #Q005 | corrective_action | health | mandatory | Investigate Turbidity Changes | drinking water | As the risk of the presence of pathogens in filtered water increases during turbidity increases and spikes, it is essential that utilities immediately investigate and determine the cause of any changes in filtered water quality. | During turbidity increases and spikes | high |
| #Q006 | operational | health | mandatory | Robust Filtration Process Requirement | drinking water | Utilities also need to ensure that the filtration process is sufficiently robust to consistently provide high-quality filtered water and ultimately to maximize public health protection. | high | |
| #Q007 | monitoring | operational | mandatory | Monitor Filter Turbidity Levels | drinking water | It is essential for utilities to monitor and understand the turbidity levels of each filter throughout its operation to ensure that both stable operation periods as well as periods when filtered water turbidity is expected to be higher are managed appropriately. | high | |
| #Q008 | design | treatment | recommended | Filter-to-Waste Feature - Slow Sand | drinking water | As is the case with conventional filtration, a "filter-to-waste" feature should be provided so that the filtered water immediately after filter cleaning is directed into a waste stream, because the initial improvement period can be as long as 1-2 days. | high | |
| #Q009 | treatment | operational | recommended | Filter Re-sanding Depth | drinking water | Once the bed depth has reached approximately 0.5 m, the filter should be re-sanded (Logsdon, 2008). | When the slow sand bed depth has reached approximately 0.5 m | high |
| #Q010 | operational | treatment | mandatory | Slow Sand Filter Adjustments in Cold Water | drinking water | Utilities will generally need to make adjustments, such as decreasing the hydraulic loading rate to the filters, during periods when the water temperature is lower, so that the overall filter performance is maintained (Logsdon, 2008). | During periods when the water temperature is lower | high |
| #Q011 | operational | treatment | recommended | Filter Run Termination - Hydraulic Surges | drinking water | Disturbance of the filter cake as a result of hydraulic surges should generally result in termination of the filter run (Fulton, 2000). | In diatomaceous earth filtration when there is a disturbance of the filter cake as a result of hydraulic surges | high |
| #Q012 | design | treatment | recommended | Filter-to-Waste Feature - Membrane | drinking water | A "filter-to-waste" feature should be provided for initial startup and commissioning of the membrane system and for emergency diversion in the event of a membrane integrity breach. | For membrane filtration systems | high |
| #Q013 | monitoring | operational | mandatory | Membrane Integrity Testing | drinking water | Therefore, integrity testing is an essential component of membrane filtration operation (U.S. EPA, 2001b, 2005). | For membrane filtration systems | high |
| #Q014 | monitoring | operational | recommended | Indicator of Membrane Integrity Breach | drinking water | Since most membrane filtration systems consistently produce water with turbidity below 0.1 NTU, utilities should consider a sustained increase in turbidity above 0.1 NTU as an indicator of a potentially serious integrity breach. | When operating membrane filtration systems | high |
| #Q015 | monitoring | operational | recommended | Direct Integrity Testing for Membranes | drinking water | In general, when utilities are using turbidity monitoring for integrity testing, they should also use a more sensitive direct integrity testing method, such as pressure decay testing, to enable the detection and location of potential minor integrity breaches (Sethi et al., 2004; MWH, 2005). | When utilities are using turbidity monitoring for membrane integrity testing | high |
| #Q016 | design | health | recommended | Certification of Bag and Cartridge Filters | drinking water | It is recommended that all components used in bag and cartridge filters be certified under NSF International (NSF)/American National Standards Institute (ANSI) Standard 61: Drinking Water System Components--Health Effects. | When using bag and cartridge filtration | high |
| #Q017 | monitoring | operational | recommended | Minimum Daily Effluent Monitoring - Bag/Cartridge | drinking water | The frequency of monitoring may vary depending on the source water quality; however, at a minimum, effluent turbidity should be monitored daily (Cleasby and Logsdon, 1999; U.S. EPA, 2003c). | When using bag and cartridge filters | high |
| #Q018 | prohibition | treatment | recommended | Municipally Treated Water Secondary Treatment | drinking water | Generally, it is not recommended that drinking water treatment devices be used to provide additional treatment to municipally treated water. | For residential-scale treatment on municipally treated water | high |
| #Q019 | operational | health | recommended | Consider Microbiological Aspects Prior to Selection | drinking water | Therefore, the microbiological aspects of the water quality should be considered prior to selection of a drinking water treatment device. | Prior to selection of a private residential drinking water treatment device for a private well | high |
| #Q020 | design | health | recommended | Certification of Residential Devices | drinking water | Health Canada does not recommend specific brands of private residential drinking water treatment devices, but it strongly recommends that consumers use devices that have been certified by an accredited certification body as meeting the appropriate NSF/ANSI drinking water treatment unit standards. | When consumers select residential drinking water treatment devices | high |
| #Q021 | design | operational | recommended | Point-of-Use Installation for Reverse Osmosis | drinking water | In addition, water that has been treated using reverse osmosis may be corrosive to internal plumbing components; therefore, these devices should be installed at the point-of-use. | When reverse osmosis systems are used for residential-scale treatment | high |
| #Q022 | monitoring | treatment | recommended | Pre-Installation Water Testing | drinking water | Before a drinking water treatment device is installed, the water should be tested to determine general water chemistry and verify the level of turbidity. | Before installing a residential-scale drinking water treatment device | high |
| #Q023 | monitoring | operational | recommended | Periodic On-site Testing | drinking water | Periodic testing on-site by a water treatment specialist using a portable turbidimeter should be conducted on both the water entering the treatment device and the water it produces to verify that the treatment device is effective. | For residential-scale drinking water treatment devices | high |
| #Q024 | operational | operational | recommended | Verification of Expected Longevity | drinking water | Consumers should verify the expected longevity of the components in their treatment device as per the manufacturer's recommendations. | For residential-scale drinking water treatment devices | high |
| Req ID | Category | Intent | Legal Status | Name | Subdomain(s) | Limit Type | Limit Value | Context | Conditions | Confidence |
|---|---|---|---|---|---|---|---|---|---|---|
| #P001 | physical | operational | guidance | Source water turbidity for direct filtration | drinking water | requirement | < 15 NTU | direct filtration is typically limited to source water with turbidity that is below 15 NTU | When using direct filtration (no sedimentation or flotation) | high |
| #P002 | physical | treatment | recommended | Individual filter effluent turbidity (optimization goal) | drinking water | treatment_goal | <= 0.10 NTU | The first optimization goal is to achieve effluent turbidities on individual filters of 0.10 NTU or less 95% of the time. | Conventional and direct filtration plants, 95% of the time | high |
| #P003 | physical | treatment | recommended | Post-backwash filtered water turbidity spike (optimization goal) | drinking water | treatment_goal | <= 0.30 NTU | The second goal is to minimize the turbidity of the post-backwash filtered water "spike" to no greater than 0.30 NTU, with turbidity returning to below 0.10 NTU in less than 15 minutes following the backwash | Following filter backwash in conventional and direct filtration | high |
| #P004 | physical | operational | guidance | Raw water turbidity for slow sand filtration | drinking water | requirement | < 10 NTU | Without any pretreatment, application of slow sand filtration is typically restricted to raw water sources with turbidity below 10 NTU | Without any pretreatment | high |
| #P005 | physical | treatment | guidance | Filtered water turbidity (slow sand filtration goal) | drinking water | treatment_goal | 0.1 NTU | reducing turbidity as low as possible, with a goal of 0.1 NTU, is an important factor in ensuring that a slow sand filtration plant has been properly designed and is being well operated. | Slow sand filtration effluent | high |
| #P006 | physical | operational | guidance | Raw water turbidity for diatomaceous earth filtration | drinking water | requirement | 5-10 NTU | Without any pretreatment, application of diatomaceous earth filtration is typically limited to raw water sources with maximum turbidity values between 5 and 10 NTU. | Without any pretreatment | medium |
| #P007 | physical | operational | guidance | Influent turbidity for reverse osmosis and nanofiltration | drinking water | requirement | < 1 NTU | Typically, reverse osmosis and nanofiltration systems are preceded by filtration by 5-20 µm cartridge filters to reduce the particulate load on the membranes and achieve an influent water quality with turbidity below 1 NTU | Prior to entering RO or nanofiltration membranes | high |
| #P008 | physical | operational | guidance | Source water turbidity for bag and cartridge filtration | drinking water | requirement | < 10 NTU | Although bag and cartridge filters can accommodate some high-turbidity source water, generally the turbidity should be below 10 NTU for effective filtration | When using bag and cartridge filters | high |
| #P009 | physical | treatment | mandatory | NSF/ANSI Standard 53 - Turbidity reduction requirement | drinking water | requirement | <= 0.5 NTU | For a drinking water treatment device to be certified to Standard 53, it must be capable of reducing a turbidity level of 11 NTU ± 1 NTU to not more than 0.5 NTU | Residential-scale treatment devices certified to NSF/ANSI Standard 53 | high |
| #P010 | physical | treatment | mandatory | NSF/ANSI Standard 58 - Turbidity reduction requirement | drinking water | requirement | <= 0.5 NTU | For a drinking water treatment device to be certified to Standard 58, it must be capable of reducing a turbidity level of 11 NTU ± 1 NTU to not more than 0.5 NTU | Reverse Osmosis Drinking Water Treatment Systems certified to NSF/ANSI Standard 58 | high |
| #P011 | design | operational | guidance | Filter loading rates (conventional/direct) | drinking water | requirement | 3.0 - 15 m/h | Filter loading rates generally range from 3.0 to 15 m/h | Conventional and direct filtration; high-rate filters can reach 33 m/h | high |
| #P012 | design | operational | guidance | Filter loading rates (slow sand) | drinking water | requirement | 0.05 - 0.4 m/h | The hydraulic loading rates are much lower for typical slow sand filters than for rapid granular filtration and range between 0.05 and 0.4 m/h. | Standard slow sand filtration operation | high |
| #P013 | design | operational | guidance | Minimum bed depth for slow sand filtration | drinking water | requirement | 0.5 m | Once the bed depth has reached approximately 0.5 m, the filter should be re-sanded. | After repeated scrapings for maintenance | high |
| #P014 | design | operational | guidance | Filter loading rates (diatomaceous earth) | drinking water | requirement | 1.3 - 5 m/h | Typical filtration rates are lower than for rapid granular filtration and range from 1.3 to 5 m/h. | Diatomaceous earth filtration processes | high |
| #P015 | design | treatment | guidance | Membrane pore size - Ultrafiltration | drinking water | requirement | 0.01 - 0.1 µm | Ultrafiltration membranes typically have a pore size range of 0.01-0.1 µm. | Specification for small colloids, particulates, and virus removal | high |
| #P016 | design | treatment | guidance | Membrane pore size - Microfiltration | drinking water | requirement | 0.1 - 10 µm | Microfiltration membranes typically have a pore size range of 0.1-10 µm. | Specification for particulates, sediment, algae, protozoa, and bacteria removal | high |
| #P017 | physical | operational | guidance | Membrane integrity breach indicator | drinking water | OG | > 0.1 NTU | utilities should consider a sustained increase in turbidity above 0.1 NTU as an indicator of a potentially serious integrity breach. | Sustained increase in membrane filtrate | high |
| #P018 | operational | reporting | recommended | Bag and cartridge filter monitoring frequency | drinking water | requirement | >= 1 per day | at a minimum, effluent turbidity should be monitored daily | Bag and cartridge filtration systems | high |
| #P019 | design | treatment | guidance | Nanofiltration particle rejection range | drinking water | requirement | 0.5 - 2 nm | Nanofiltration membranes are reported to reject particles in the size range of 0.5-2 nm. | Standard nanofiltration membrane classification | high |
| #P020 | operational | treatment | guidance | Slow sand filtration initial improvement period | drinking water | requirement | 1 - 2 days | initial improvement period can be as long as 1-2 days | Immediately after filter cleaning/scraping | high |
| #P021 | design | treatment | guidance | Diatomaceous earth precoat thickness | drinking water | requirement | 3 mm | the septum is coated with a thin layer of diatomaceous earth (precoat) about 3 mm thick | Start of a filter run | high |
| #P022 | operational | treatment | recommended | Post-backwash ripening duration goal | drinking water | treatment_goal | < 15 minutes | with turbidity returning to below 0.10 NTU in less than 15 minutes following the backwash | Following backwash in optimized plants | high |
| #P023 | design | treatment | guidance | Bag and cartridge filtration particle removal capability | drinking water | requirement | > 1 µm | separation processes that remove particles greater than 1 µm using a porous filtration medium | Standard bag/cartridge filter configuration | high |
| #P024 | design | treatment | guidance | Bag filter pore size range | drinking water | requirement | 1 - 40 µm | Bag filters typically have pore sizes that range from 1 to 40 µm | high | |
| #P025 | design | treatment | guidance | Cartridge filter pore size range | drinking water | requirement | 0.3 - 80 µm | those of cartridge filters typically range from 0.3 to 80 µm | high | |
| #P026 | design | operational | guidance | RO and Nanofiltration pre-filtration requirement | drinking water | requirement | 5 - 20 µm | Typically, reverse osmosis and nanofiltration systems are preceded by filtration by 5-20 µm cartridge filters | Pre-treatment to reduce membrane fouling | high |
| #P027 | operational | operational | guidance | Slow sand filtration schmutzdecke removal depth | drinking water | requirement | 1 - 2 cm | the filter is drained and the top 1-2 cm of schmutzdecke is removed | During filter regeneration/scraping | high |
| #P028 | physical | operational | recommended | Preferred raw water turbidity for slow sand filtration | drinking water | requirement | < 5 NTU | some research indicates that raw water below 5 NTU is preferable | Slow sand filtration without pretreatment | high |
| #P029 | physical | health | mandatory | Health-Based Treatment Limit (HBTL) - 95th Percentile (Conventional/Direct) | drinking water | MAC | <= 0.3 NTU | Meeting the HBTL for conventional and direct filtration systems is feasible and achievable for well-operated plants. | Applicable to 95% of measurements each month | high |
| #P030 | physical | health | mandatory | Health-Based Treatment Limit (HBTL) - Maximum (Conventional/Direct) | drinking water | MAC | <= 1.0 NTU | Maintaining a maximum filtered turbidity level below 1.0 NTU is readily achievable for conventional and direct filtration plants. | Maximum value not to be exceeded | high |
| #P031 | physical | health | mandatory | Health-Based Treatment Limit (HBTL) - Maximum (Slow Sand) | drinking water | MAC | <= 1.0 NTU | Slow sand filtration plants are able to achieve filtered water turbidity below 1.0 NTU consistently. | Effluent turbidity after establishing biopopulation | high |
| #P032 | physical | health | mandatory | Health-Based Treatment Limit (HBTL) - Maximum (Diatomaceous Earth) | drinking water | MAC | < 1.0 NTU | Well-operated diatomaceous earth filtration plants are readily capable of producing filtered water with turbidity of less than 1 NTU. | During standard filter operation cycles | high |
| #P033 | design | operational | guidance | High-rate filtration loading rate capacity | drinking water | requirement | <= 33 m/h | While standard rates range from 3.0 to 15 m/h, some high-rate filters are capable of higher speeds. | Specific design for high-rate granular filters | high |
| #P034 | physical | treatment | mandatory | NSF/ANSI Standard 53 and 58 Influent Challenge Level | drinking water | requirement | 11 +/- 1 NTU | Standardized test conditions for certifying residential-scale treatment devices. | Influent challenge concentration for certification testing | high |
| #P035 | physical | treatment | guidance | Filtered water turbidity (Microfiltration and Ultrafiltration) | drinking water | treatment_goal | < 0.1 NTU | In general, microfiltration and ultrafiltration processes achieve filtered water turbidity of less than 0.1 NTU. | Standard microfiltration or ultrafiltration membrane systems | high |
| #P036 | design | treatment | guidance | Staged bag and cartridge filtration (pre-filter stage) | drinking water | requirement | > 10 µm | In some cases, bag and/or cartridge filters are placed in series, with larger pore size units (greater than 10 µm) placed first | When using bag or cartridge filters in a series configuration | high |
| #P037 | design | treatment | guidance | Staged bag and cartridge filtration (final stage) | drinking water | requirement | 1 - 5 µm | followed by smaller pore size units (1-5 µm) as final filter units | When using bag or cartridge filters in a series configuration | high |
| Req ID | Category | Name | Context | Confidence |
|---|---|---|---|---|
| #D001 | Interim Enhanced Surface Water Treatment Rule | Interim Enhanced Surface Water Treatment Rule (IESWTR) | high | |
| #D002 | Partnership for Safe Water | Partnership for Safe Water (PSW) | high | |
| #D003 | Reverse osmosis | a high-pressure membrane process originally developed to remove salts from brackish water. The reverse osmosis process is based on diffusion of water through a semi-permeable membrane as a result of a concentration gradient. Reverse osmosis membranes are considered to be non-porous and are used to remove dissolved solids, such as sodium, chloride and nitrate, from water. | high | |
| #D004 | Nanofiltration | a low-pressure reverse osmosis process for the removal of larger cations (e.g., calcium and magnesium ions) and organic molecules. Nanofiltration membranes are also typically considered non-porous and are reported to reject particles in the size range of 0.5-2 nm. | high | |
| #D005 | Ultrafiltration | a lower-pressure membrane process characterized by a wide band of molecular weight cut-off and pore sizes for the removal of small colloids, particulates and, in some cases, viruses. Ultrafiltration membranes typically have a pore size range of 0.01-0.1 µm. | high | |
| #D006 | Microfiltration | a low operating pressure membrane process used to remove particulates, sediment, algae, protozoa and bacteria. Microfiltration membranes typically have a pore size range of 0.1-10 µm. | high | |
| #D007 | Long Term 2 Enhanced Surface Water Treatment Rule | Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) | high | |
| #D008 | American National Standards Institute | American National Standards Institute (ANSI) | high | |
| #D009 | Standards Council of Canada | Standards Council of Canada (SCC) | high | |
| #D010 | Conventional filtration process | generally includes chemical mixing, coagulation, flocculation, sedimentation (or dissolved air flotation) and rapid granular filtration | high | |
| #D011 | Direct filtration process | includes coagulation and flocculation; however, no sedimentation or flotation is used, and flocculated water proceeds directly to filtration | high | |
| #D012 | Robust filtration process | one that performs well both under normal operating conditions as well as during periods when filters may be challenged, such as during high source water turbidity events or coagulation upsets | high | |
| #D013 | breakthrough phases | phases when ultimately the filtered water turbidity will reach a maximum value | high | |
| #D014 | schmutzdecke | a layer of bacteria, algae and other microorganisms on the surface of the sand | high | |
| #D015 | biopopulation | a biological population within the sand bed | high | |
| #D016 | Direct integrity testing | procedures applied directly to the membrane or membrane module to determine whether there is an integrity breach and, if there is, its source | high | |
| #D017 | Indirect integrity testing | a surrogate measure of integrity based on monitoring the water quality of the filtrate | high | |
| #D018 | NSF | NSF International | high | |
| #D019 | Slow sand filtration process | generally consists of untreated water slowly flowing by gravity through a bed of submerged porous sand. | high | |
| #D020 | Diatomaceous earth filters | consist of a vessel that contains many filtration devices called filter elements or leaves. | high | |
| #D021 | septum | a porous membrane or fabric referred to as a septum that holds the filter cake during filtration. | high | |
| #D022 | precoat | a thin layer of diatomaceous earth (precoat) about 3 mm thick. | high | |
| #D023 | body feed | a small amount of diatomaceous earth is continually added as body feed to maintain a permeable filter cake. | high | |
| #D024 | Bag filters | typically constructed of a woven bag or fabric filtration medium that is placed in a pressure vessel. | high | |
| #D025 | Cartridge filters | typically made of a semi-rigid or rigid wound filament that is housed in a pressure vessel in which water flows from the outside of the cartridge to the inside. | high | |
| #D026 | pre-ripening period | period in which the turbidity increases due to the influence of post-backwash remnants above and within the filter. | high | |
| #D027 | ripening period | period in which the turbidity decreases and approaches the level maintained during the stable filter operation phase. | high | |
| #D028 | filter-to-waste | the filtered water produced immediately after filter backwashing is directed into a waste stream. | high |