| Req ID | Category | Intent | Legal Status | Name | Subdomain(s) | Context | Conditions | Confidence |
|---|---|---|---|---|---|---|---|---|
| #Q001 | treatment | treatment | recommended | Determination of pretreatment needs | drinking water | It is important to determine what, if any, pretreatment is required. | high | |
| #Q002 | monitoring | operational | guidance | Arsenic speciation assessment | drinking water | Speciation may be performed to assess the species of arsenic present; however, there appears to be limited benefit with respect to time and costs involved. | high | |
| #Q003 | treatment | operational | recommended | Lime softening restriction | drinking water | However, lime softening is an expensive process and is not recommended unless there is also a need to reduce hardness in the raw water feed (U.S. EPA, 2000). | Unless there is also a need to reduce hardness in the raw water feed | high |
| #Q004 | treatment | operational | recommended | Ion exchange application | drinking water | These systems are recommended for water supplies with low concentrations of total dissolved solids and sulphate (U.S. EPA, 2000). | For water supplies with low concentrations of total dissolved solids and sulphate | high |
| #Q005 | monitoring | operational | recommended | Residential treatment device monitoring | drinking water | Periodic testing by an accredited laboratory should be conducted on both the water entering a treatment device and the water it produces to verify that the device is effective. | high | |
| #Q006 | monitoring | operational | recommended | Pre-installation well water testing | drinking water | Before a treatment device is installed, the well water should be tested to determine general water chemistry and to verify the concentration of arsenic. | Before a treatment device is installed | high |
| #Q007 | monitoring | operational | recommended | Testing for competing ions and organic matter | drinking water | The testing should also include assessing the presence and concentration of competing ions (e.g., fluoride, iron, sulphate, silicate) and organic matter in the water, which could interfere with arsenic removal. | high | |
| #Q008 | treatment | treatment | recommended | Pretreatment oxidation step for residential systems | drinking water | Given that most technology cannot effectively remove trivalent arsenic, pretreatment with an oxidation step is recommended to convert trivalent (dissolved) arsenic to pentavalent (filterable) arsenic, to ensure good removal by the treatment device (U.S. EPA, 2001a). | high | |
| #Q009 | operational | operational | recommended | Review of manufacturer claims | drinking water | Individuals should refer to the manufacturer's claims in its literature to obtain information on the amount of arsenic that the treatment device will remove, as well as operational and maintenance requirements. | high | |
| #Q010 | treatment | operational | guidance | Influent water pretreatment for membrane protection | drinking water | A consumer may need to pretreat the influent water to reduce fouling and extend the service life of the membrane. | When using reverse osmosis systems | high |
| #Q011 | operational | health | recommended | Dietary compensation for mineral removal | drinking water | Since beneficial minerals such as calcium and magnesium are removed by both distillation and reverse osmosis processes, it is important to consume a reasonably well-balanced diet to offset the removal of these minerals. | When using distillation or reverse osmosis processes | high |
| #Q012 | treatment | health | recommended | Use of certified treatment devices | drinking water | Health Canada does not recommend specific brands of treatment devices, but it strongly recommends that consumers use devices that have been certified by an accredited certification body as meeting the appropriate NSF International (NSF)/American National Standards Institute (ANSI) drinking water treatment unit standards. | high | |
| #Q013 | administrative | reporting | mandatory | Accreditation of certification organizations | drinking water | Certification organizations provide assurance that a product conforms to applicable standards and must be accredited by the Standards Council of Canada (SCC). | high | |
| #Q014 | monitoring | operational | recommended | Finished water testing to verify treatment efficacy | drinking water | It is important to determine what, if any, pretreatment is required and to have the finished water tested by an accredited laboratory to ensure that any designed system is attaining the desired arsenic removal. | high | |
| #Q015 | operational | operational | mandatory | Disposal of treatment residuals | drinking water | These systems also create significant quantities of either sludge or brine, which must be disposed of appropriately, thus increasing the cost of these processes (NDWAC, 2001). | Applicable to municipal-scale arsenic treatment technologies | high |
| Req ID | Category | Intent | Legal Status | Name | Subdomain(s) | Limit Type | Limit Value | Context | Conditions | Confidence |
|---|---|---|---|---|---|---|---|---|---|---|
| #P001 | chemical | treatment | mandatory | Arsenic (NSF/ANSI Certification Final Concentration) | drinking water | requirement | < 0.010 mg/L | Certification to the standard verifies only that a final concentration of less than 0.010 mg/L is achieved. | Applies to residential drinking water treatment devices certified to NSF/ANSI standards. | high |
| #P002 | chemical | treatment | mandatory | Arsenic (NSF/ANSI Standards 53, 58, 62 Influent Challenge) | drinking water | requirement | 0.3 mg/L | The device will have to be able to reduce the concentration of arsenic in water from 0.3 to 0.010 mg/L. | For a drinking water treatment device to be certified to NSF/ANSI Standards 53, 58, or 62 (high concentrations). | high |
| #P003 | chemical | treatment | guidance | Arsenic (NSF/ANSI Standards Low Influent Challenge) | drinking water | requirement | < 0.05 mg/L | Devices certified as reducing the concentration of arsenic from 0.05 to 0.010 mg/L are intended for treating water with lower initial concentrations (i.e., less than 0.05 mg/L) of arsenic. | Intended for treating water with lower initial concentrations of arsenic. | high |
| #P004 | physical | treatment | guidance | Arsenic Speciation pH Range | drinking water | OG | 4-10 pH | In water in the pH range of 4-10, the predominant As(III) species are neutral in charge, while As(V) species are negatively charged. | Relevant for assessing removal efficiency of As(III) vs As(V). | high |
| #P005 | chemical | treatment | guidance | Coagulation/Filtration Finished Water Arsenic Concentration | drinking water | treatment_goal | 0.003-0.005 mg/L | when coagulation/filtration is combined with pretreatment (oxidation to convert arsenic to its pentavalent form) and a polishing step (polishing the finished water with ion exchange) | Total arsenic levels in finished drinking water. | high |
| #P006 | chemical | treatment | guidance | Lime Softening Finished Water Arsenic Concentration | drinking water | treatment_goal | 0.001-0.003 mg/L | Lime softening is widely used in large utilities and is effective at reducing total arsenic in drinking water | Typically used when there is also a need to reduce hardness. | high |
| #P007 | chemical | treatment | guidance | Activated Alumina Effluent Arsenic Level | drinking water | treatment_goal | < 0.01 mg/L | Pilot plant studies of arsenic removal using activated alumina achieved effluent arsenic levels of <0.01 mg/L | Simms and Azizian, 1997 study. | high |
| #P008 | design | treatment | guideline | Activated Alumina Removal Efficiency | drinking water | treatment_goal | 95 % | The U.S. EPA has identified activated alumina as a best available technology for arsenic removal, with a removal efficiency of 95% | U.S. EPA, 2001a reference. | high |
| #P009 | chemical | treatment | guidance | Ion Exchange Finished Water Arsenic Concentration | drinking water | treatment_goal | 0.003 mg/L | Ion exchange processes in combination with an oxidation pretreatment step have been shown to reduce total arsenic in finished drinking water to levels as low as 0.003 mg/L. | Recommended for water supplies with low TDS and sulphate. | high |
| #P010 | design | treatment | guidance | Reverse Osmosis Municipal Removal Efficiency | drinking water | treatment_goal | 85 % | Reverse osmosis systems, when combined with a pretreatment step, can remove up to 85% of total arsenic from drinking water. | May not be suitable where water resources are scarce due to brine rejection. | high |
| #P011 | chemical | treatment | guidance | Iron Oxide-Coated Sand Adsorption Effluent | drinking water | treatment_goal | < 0.005 mg/L | iron oxide-coated sand and granular ferric hydroxide can remove As(III) and As(V) present in the water to a concentration below 0.005 mg/L | Applicable to small water treatment utilities. | high |
| #P012 | chemical | treatment | guideline | Residential Treatment Device Arsenic Concentration | drinking water | treatment_goal | < 0.010 mg/L | Residential treatment devices are affordable and can remove arsenic from drinking water to concentrations below 0.010 mg/L. | Private residential drinking water treatment device. | high |
| #P013 | design | treatment | guidance | Residential Reverse Osmosis Mineral Removal Efficiency | drinking water | requirement | 98 % | can remove up to 98% of other dissolved minerals as well as fine colloidal and coarse suspended matter | Major advantage of reverse osmosis systems. | high |
| #P014 | chemical | treatment | guidance | Professionally Designed Residential System Effluent | drinking water | treatment_goal | < 0.005 mg/L | A qualified professional can design a system to meet residential needs and achieve arsenic concentrations below 0.005 mg/L. | For example, a system designed with two or more filters in series. | high |
| #P015 | design | treatment | guidance | Municipal Scale Technology General Removal Efficiency | drinking water | treatment_goal | > 90 % | Removal efficiency can be very good (>90%) for technologies including coagulation/filtration, lime softening, activated alumina, ion exchange, and reverse osmosis. | high | |
| #P016 | chemical | treatment | guidance | Ion Exchange Laboratory Column Study Effluent | drinking water | treatment_goal | 0.002 mg/L | Laboratory column studies using ion exchange resin achieved effluent concentrations as low as 0.002 mg/L where the influent had an arsenic concentration of 0.021 mg/L. | Influent concentration of 0.021 mg/L | high |
| #P017 | chemical | treatment | guidance | Ion Exchange Laboratory Column Study Influent Concentration | drinking water | requirement | 0.021 mg/L | Laboratory column studies using ion exchange resin achieved effluent concentrations as low as 0.002 mg/L where the influent had an arsenic concentration of 0.021 mg/L. | high |
| Req ID | Category | Name | Context | Confidence |
|---|---|---|---|---|
| #D001 | treatment device | private residential drinking water treatment device | high | |
| #D002 | point of use | at the faucet | medium | |
| #D003 | point of entry | where water enters the home | medium | |
| #D004 | NSF | NSF International | high | |
| #D005 | ANSI | American National Standards Institute | high | |
| #D006 | SCC | Standards Council of Canada | high | |
| #D007 | water blending | combining water from a source that has high levels of arsenic with one that has a much lower concentration of arsenic | high | |
| #D008 | influent | incoming | high | |
| #D009 | reject | waste | high | |
| #D010 | trivalent arsenic | dissolved arsenic | high | |
| #D011 | pentavalent arsenic | filterable arsenic | high | |
| #D012 | NSF/ANSI Standard 53 | Drinking Water Treatment Units -- Health Effects | high | |
| #D013 | NSF/ANSI Standard 58 | Reverse Osmosis Drinking Water Treatment Systems | high | |
| #D014 | NSF/ANSI Standard 62 | Drinking Water Distillation Systems | high |