Water treatment plant disinfection procedure

When the procedure will take effect

This procedure will take effect through conditions in the Drinking Water Works Permit. It will replace ANSI/AWWA Standard C653 (AWWA C653). There are 2 scenarios that will apply depending on the timing of a system’s Municipal Drinking Water Licence renewal:

• permits specifying timelines for transition (scenario 1)
• permits that do not specify timelines for transition (scenario 2)

Drinking water systems must follow AWWA C653 unless their permit, or the ministry, authorizes them to use the Water Treatment Plant Disinfection Procedure earlier. Drinking water systems cannot partially implement the procedure.

Scenario 1: Permits specifying timelines for transition

If the licence for your system was renewed between 2023 and 2026, your permit includes an updated condition, typically condition 2.3.3 in Schedule B. This condition requires you to transition from AWWA C653 to this procedure within 6 months of its issuance.

Scenario 2: Permits that do not specify timelines for transition

If your permit does not include a condition requiring changing to this procedure, this requirement will be added in a future permit amendment. You are encouraged to consider early adoption and implementation of this procedure which can be requested by contacting the ministry at mdwlp@ontario.ca. Otherwise, you are required to use AWWA C653 until conditions in your permit indicate otherwise or you receive authorization to use the new procedure.

Preface

This Water Treatment Plant Disinfection Procedure (“this procedure”) is a supporting document for Ontario legislation and regulations related to drinking water. Schedule B, Condition 2.3 of the Drinking Water Works Permit adopts this procedure by reference. Where this procedure refers to ANSI/AWWA Standard C653 - “Standard for Disinfection of Water Treatment Plants”, the current version of the standard shall be used. The section numbers in this procedure match the section numbers of the 2020 version of AWWA C653. When an updated version of the standard is released, its corresponding section(s) and amended wording will supersede the requirements of the previous version. Definitions are listed in Appendix A and should be reviewed prior to using this procedure.

Table A (below) shows the applicable disinfection procedure for each component by location. Determine the proper disinfection procedure for a particular component by selecting its location from the “Location” column of Table A. Find the specific component to be disinfected within the rows for the selected location. Use the procedure named in the column heading above the selected component to disinfect that component. Sampling and documentation shall be completed as per the identified procedure, unless otherwise indicated in section 5 of this procedure.

Operating authorities shall use certified operators for activities that must be performed by a certified operator. Water quality analysts may perform sampling and testing if permitted through regulation. Components may only be isolated and placed into service by certified operators. Activities performed on isolated components are not required to be performed by certified operators (unless specified otherwise in this procedure). These activities, including taking microbiological samples and performing chlorine residual concentration testing, may be performed by any person authorized by the operating authority.

Operating authorities may use best management practices that exceed the minimum requirements in this procedure.

Deviations from the requirements of this procedure shall be requested and approved in advance by the Director.

1. Modifications to section 1 of AWWA C653 – general

Operating authorities shall ensure that the requirements of AWWA C653, as modified by this procedure, are followed. For clarity, where this procedure states no disinfection is required for a component, the microbiological sampling required after its disinfection is also not required.

No disinfection is required if a filter is emptied and no maintenance is performed, provided the operating authority is satisfied that sanitary practices were used. Examples of sanitary practices are:

• cleaning observation hatches (or covers as applicable) and immediate area of loose dirt and debris prior to opening
• if applicable, cleaning boots and spraying with a minimum 1% chlorine solution immediately prior to entering the filter

Where an operating authority believes that contaminated or improperly disinfected water was directed to users, the reporting requirements from Schedule 16-4 of Ontario Regulation 170/03 shall apply. The applicable corrective actions outlined in Schedules 17 or 18 of O. Reg. 170/03 shall also apply.

2. Modifications to section 2 of AWWA C653 – references

In addition to the standards referred to in section 2 of AWWA C653, this procedure refers to these 3 ministry’s procedures:

• Watermain Disinfection Procedure
• Water Storage Facility Disinfection Procedure
• Municipal Drinking Water Well Disinfection Procedure

In their latest editions, these 3 documents form a part of this procedure to the extent specified within this procedure.

3. Modifications to section 3 of AWWA C653 – definitions

Appendix A of this procedure includes additional definitions, beyond those in section 3 of AWWA C653. In case of conflict, the definitions from this procedure will supersede the definitions of AWWA C653.

Where AWWA C653 refers to potable water, the definition of drinking water in Appendix A shall be used.

4. Modifications to section 4 of AWWA C653 – requirements

At concentrations over 10 mg/L, measurements of total chlorine and free chlorine shall be deemed equivalent.

4.1 Materials and cleaning

No modification to this section.

4.2 Units requiring disinfection

This section applies to any component requiring disinfection using this procedure as per Table A and its associated footnotes. Prior to placing into service, operating authorities shall clean chemical feed system components. Components of chemical feed system at or after the first inactivation process, other than a disinfectant feed system, shall be disinfected. Examples of inactivation processes are chlorination, ultraviolet lights and ozone. The disinfection shall be performed by rinsing with a solution at a minimum 200 mg/L chlorine concentration. Operating authorities may require a retention time after the chlorine solution is applied. Spraying or swabbing are acceptable alternatives to rinsing. When dealing with chemicals that are not compatible with chlorine, operating authorities shall consider rinsing with drinking water following the chlorine rinse.

4.3 Forms of chlorine for disinfection and rinsing

Chemicals used for disinfection shall meet the requirements of both of these standards:

• American Water Works Association (AWWA)
• American National Standards Institute (ANSI) safety criteria standard NSF/ANSI/CAN 60

The same requirements apply for the chlorine solution used for rinsing as per section 4.2 of this procedure. The equipment used to apply the chlorine solution is not required to meet the requirements of NSF/ANSI/CAN 61. It shall however only be used for chlorine solution applications. Deviations allowing the use of alternate disinfection chemicals (for example, hydrogen peroxide) shall be requested and approved in advance by the Director.

4.4 Plant disinfection procedures

Handling of water discharges to the natural environment

Operating authorities shall take steps to ensure that discharges of water to the natural environment comply with Condition 10.0 of Schedule B of the Municipal Drinking Water Licence. This includes following the requirements of section 4.4.3.6 of AWWA C653 for dechlorination. Follow ANSI/AWWA C655: Field dechlorination, until the total chlorine residual concentration is no more than 0.02 mg/L in any of these situations:

• for any water that is directly discharged into surface water
• if the discharge into the natural environment is likely to cause an adverse effect

If the dechlorinated discharged water meets the requirements of Condition 5.5 of Schedule C of the Municipal Drinking Water Licence, the discharge is considered a Class I spill. Class I spills are defined in Ontario Regulation 675/98 made under the Environmental Protection Act.

Operating authorities may allow the use of hydrogen peroxide in addition to the dechlorination chemicals mentioned in section 4.2.3 of ANSI/AWWA C655: Field dechlorination. Deviations allowing the use of other alternate dechlorination chemicals shall be requested and approved in advance by the Director.

4.4.1 Plant piping

In lieu of section 4.4.1 of AWWA C653, this procedure divides plant piping into 3 categories: raw water piping, process water piping and drinking water piping. Refer to Table A and associated footnotes for the disinfection requirements.

4.4.2 Tanks and clearwells

Cleaning, disinfection and sampling for tanks and clearwells shall be performed as per the Water Storage Facility Disinfection Procedure.

4.4.3 Filters

Operating authorities shall follow the applicable disinfection requirements in sections 4.4.3.3 and 4.4.3.4 of AWWA C653. In addition, operating authorities shall spray all filter walls above normal operating water level (such as freeboard) that may come in contact with water. The spraying shall be performed using a minimum 200 mg/L chlorine solution. Operating authorities may require a retention time after the 200 mg/L chlorine solution is applied.

The following sections include additional requirements to section 4.4.3 of AWWA C653:

A – Filters with granulated activated carbon (GAC)

For granulated activated carbon (GAC) filters, the spraying of filter walls above normal operating water level mentioned above shall occur prior to adding the GAC to the filter.

When GAC is added to a filter, the operating authority shall ensure that sanitary practices are used when storing, handling and installing the GAC. This includes the cleaning and disinfection steps for equipment and workers from section 4.4.3.5 of AWWA C653.

B – Cartridge filters

For clarity, this section is not intended for routine filter cartridge replacements. This section only applies to the following activities:

• the initial installation of cartridge filter units
• a situation in which these filter units are taken out of service for maintenance or repair
• any other activity or event that might lead to water being contaminated

Filter cartridges shall be stored, handled and installed using sanitary practices. No disinfection of the cartridge or housing is required if only replacing a cartridge and sanitary practices were followed.

Raw water filter housings require cleaning as per section 4.1 of AWWA C653, but do not require disinfection.

Process water filter housings require cleaning as per section 4.1 of AWWA C653. Disinfect filter housings by 1 of these 2 methods:

• Spraying all surfaces that come in contact with water with a minimum 1% chlorine solution.
• Filling the filter housing with a chlorine solution of not less than 10 mg/L and retain for a minimum of 6 hours. If an operating authority cannot wait for the 6-hour retention period, the operating authority may:
  • use a chlorine solution of not less than 60 mg/L
  • retain the solution for a minimum of 1 hour

If a process water filter cartridge is temporarily removed during maintenance and sanitary practices are followed, no disinfection of the cartridge is required.

C – Membrane filters

When membrane units are submerged in a filter basin, the spraying of filter basin walls above normal operating water level mentioned above shall occur prior to installing the membranes.

If the operating authority ensures that sanitary practices are used during storage, handling, installation and repairs, polymer-based membranes do not require disinfection. These membranes require:

• Flushing when deemed appropriate by the operating authority.
• Maintenance cleaning prior to placing into service. Maintenance cleaning is not required following pinning of membrane fibres contained in cylinders.

For other types of membranes (for example, ceramic), deviations from the requirements of this procedure shall be requested and approved in advance by the Director.

D - Greensand filters

Raw water greensand filters require cleaning as per section 4.1 of AWWA C653, but no disinfection unless requested by the operating authority.

Process water greensand filters require cleaning as per section 4.1 of AWWA C653 and disinfection as per section 4.4.3.3 of AWWA C653.

4.4.4 Water pumps

Operating authorities shall use the following steps for disinfection of process water or drinking water pumps:

1. Clean or flush the pump.
2. Disinfect by using 1 of these methods:
   • Spray all surfaces that come in contact with water with a minimum 1% chlorine solution.
   • Fill the pump with a chlorine solution of not less than 10 mg/L and retain for a minimum of 6 hours. If an operating authority cannot wait for the 6-hour retention period, the operating authority may:
     • use a chlorine solution of not less than 60 mg/L
     • retain the solution for a minimum of 1 hour.
   • Where possible, flush the pump until both of the following conditions are met:
     • the water appears visibly free from discoloration and particulates
     • the chlorine residual concentration is acceptable to the operating authority.

4.4.5 Ultraviolet units

As long as sanitary practices are maintained, disinfection is not required for ultraviolet (UV) unit:

• bulb replacement
• sleeve cleaning or replacement
• sensor servicing or replacement

For new installation or replacement of UV units, the operating authorities shall follow the manufacturer’s disinfection procedures or instructions that pertain to the UV unit.

5. Modifications to section 5 of AWWA C653 – verification

5.1 Water quality sampling and testing

The sampling and testing requirements in this section apply to any component requiring disinfection as per this procedure as per Table A and its footnotes.

5.1.1 General requirements - Microbiological sampling and chlorine testing

All microbiological samples shall be taken and handled as per the ministry’s Practices for the Collection and Handling of Drinking Water Samples document (as amended).

When microbiological samples are taken from an isolated component, additional samples shall be taken at the same time from the same location. These samples shall be tested immediately for 1 of the parameters below:

• free chlorine residual concentration if the system provides chlorination and does not provide chloramination
• combined chlorine residual concentration if the system provides chloramination

Any person authorized by the operating authority may take microbiological samples from isolated components and perform the associated chlorine residual concentration tests.

Operating authorities shall use a chlorine meter to test the chlorine concentrations for compliance with the disinfection requirements as per section 4 of this procedure. The ministry does not allow the use of test strips to measure the chlorine concentrations recorded to demonstrate compliance with this procedure.

Operating authorities may allow the concentration to be calculated in these 2 situations where it is impractical:

• to measure the chlorine concentration of a solution used for disinfection
• to take samples for chlorine concentration testing from the component after it has been filled

Microbiological sample results obtained from isolated water treatment plant and/or component shall be uploaded to the ministry’s database by the laboratory. Non-satisfactory results from these samples are not reportable under Schedule 16 of O. Reg. 170/03.

If non-satisfactory microbiological sample results are received (show the presence of Escherichia coli or total coliforms), refer to the instructions in section 5.1 of AWWA C653. When refilling a component with raw or process water after disinfection, corrective actions after non-satisfactory microbiological samples shall be at the discretion of the operating authority.

5.1.2 Plant piping and appurtenances

For clarity, operating authorities shall sample any water piping and appurtenances requiring disinfection as per the following sections of the Watermain Disinfection Procedure:

• new piping (including appurtenances): sections 1.1.3 or 1.1.4, as applicable, of the Watermain Disinfection Procedure
• planned maintenance of appurtenances and fittings: section 1.4 of the Watermain Disinfection Procedure
• emergency repairs of piping: section 2 of the Watermain Disinfection Procedure (if sampling is required)

5.1.3 Filters

A - Cartridge filters

The sampling requirements in this section apply to any cartridge filter housings requiring disinfection as per section 4.4.3 of this procedure.

An operating authority may allow a cartridge filter to be placed into service with no microbiological sample if all the following criteria are met:

• a certified operator is present to witness the disinfection of the cartridge filter housing
• this certified operator ensures that the sanitary practices and disinfection requirements as per section 4.4.3 B of this procedure are met

If no certified operator is present, the operating authority shall ensure that 1 microbiological sample is taken from water that has been directed through the cartridge filter.

B - Other filters

The sampling requirements in this section apply to any filter basins, membranes, greensand filters and any other type of filters other than cartridge filters. For filters with GAC, operating authorities shall obtain the microbiological samples prior to adding the GAC.

After the disinfection steps are completed and before a disinfected filter is placed into service, the operating authority shall take a minimum of 2 microbiological samples. The samples are to be taken a minimum of 30 min apart, from 1 location at the filter. The operating authority shall endeavour to have water flow continuously from the sample point between microbiological samples.

Although the microbiological sampling location is at its discretion, the operating authority shall endeavour to take the samples from the filter outlet piping. The operating authority may also require taking additional microbiological samples at any other locations.

5.1.4 Water pumps or UV units

The sampling requirements in this section apply to any drinking and process water pumps requiring disinfection using this procedure as per Table A and its associated footnotes. No sampling is required for work on UV units that do not require disinfection.

An operating authority may allow a water pump or a UV unit to be placed into service with no microbiological sample if all the following criteria are met:

• a certified operator is present to witness the disinfection of the water pump or UV unit
• this certified operator ensures that the sanitary practices and disinfection requirements as per section 4.4.4 or 4.4.5 of this procedure are met

If no certified operator is present, the operating authority shall ensure that 1 microbiological sample is taken from water that has been directed through the pump or UV unit.

Operating authorities shall endeavour to take microbiological samples and associated chlorine residual tests from water that came only from the new/repaired pump or UV unit. This is preferable to sampling from a combined header where the water from the pump or UV unit is mixed with other water.

5.1.5 Suggested sampling in section 5.1 of AWWA C653

Section 5.1 of AWWA C653 suggests testing for turbidity, pH, alkalinity, odour and specific conductance when a disinfected component is filled but not immediately placed into service. This testing shall be considered as optional and at the discretion of the operating authority. Determinations of acceptable values and corrective action(s) for these parameters shall be at the discretion of the operating authority.

5.1.6 Placing components into service

Operating authorities shall endeavour to place disinfected components into service as soon as possible after receiving satisfactory microbiological sample results. Operating authorities shall ensure that sanitary practices are followed after disinfection to prevent possible contamination until components are placed into service.

Determination of acceptable chlorine residual concentration(s) prior to placing the isolated component into service shall be at the discretion of the operating authority.

If a filter is filled after being left empty more than 5 days after the component was disinfected:

• The operating authority shall obtain 1 set of microbiological samples as per section 5.1.1 of this procedure. These samples are not required for process water cartridge filters that do not provide log removal/inactivation credits or raw water cartridge filters.
• The operating authority shall wait for satisfactory microbiological sample results prior to placing the component into service. “Exception – Placing component into service prior to receiving microbiological sample results” from section 5.1.7 of this procedure does not apply.

If a process water filter was not placed into service within 5 days after being filled after disinfection, the operating authority shall flush/backwash/backpulse or any additional measures at the discretion of the operating authority until both conditions below are met:

• the filter effluent turbidity is below 1.0 NTU
• the operating authority deems the filter contents fit to be directed to the next treatment process

5.1.7 Exception – Placing components into service prior to receiving microbiological sample results

The intent of this procedure is for operating authorities to keep disinfected components requiring microbiological sampling isolated until satisfactory microbiological sample results are received.

There are circumstances where it may be impractical to wait for the microbiological sample results before placing the disinfected component into service (meaning, water directed to users). The following are examples of acceptable circumstances:

• when the ability to meet drinking water demand may be compromised
• when stored drinking water levels may fall below acceptable limits

In these circumstances, the operating authority may place an isolated component into service prior to receiving satisfactory microbiological sample results. Notification to the local ministry office and Medical Officer of Health is not required if an Operator-in-Charge confirms cleaning and disinfection of the component met this procedure.

Any drinking water microbiological samples and their associated chlorine residual concentration tests shall be deemed as drinking water samples within the meaning of O. Reg. 170/03:

• these samples and tests shall be taken by a certified operator or a water quality analyst
• these results shall be uploaded to the ministry’s database by the laboratory
• the following shall apply to adverse microbiological sample and/or chlorine residual concentration test results:
  • the reporting requirements outlined in Schedule 16-3 of O. Reg. 170/03
  • the applicable corrective actions outlined in Schedules 17 or 18 of O. Reg. 170/03

For disinfected raw or process water components, the operating authority shall arrange to take all the following samples:

• The microbiological samples from the isolated component as per section 5.1.1 of this procedure.
• Additional microbiological samples and chlorine concentration tests from the treated water sampling point. These shall be taken at an estimated point in time when both of the following criteria are met:
  • the water from the disinfected component is believed to have achieved “primary disinfection”
  • the water has reached the treated water sampling point

5.2 Record of compliance (documentation)

When using this procedure, operating authorities shall maintain records of the following information as a minimum. The information shall be retained as per the record-keeping requirements of section 27 of O. Reg. 128/04 and Condition 13.0 of Schedule B of the Municipal Drinking Water Licence. This section does not require that all the information be recorded on a single form.

• Statement that all surfaces of components requiring cleaning were cleaned as per section 4.1 of AWWA C653.
• If applicable, statement that chemical system components requiring cleaning and rinsing, as per section 4.2 of this procedure, were:
  • rinsed (or alternatively sprayed or swabbed) with a solution at a minimum 200 mg/L chlorine concentration
  • rinsed with drinking water afterwards if necessary
• Type of water used for cleaning and/or disinfection (raw, process or drinking water).
• For the chemical used for disinfection, include all the following items:
  • name and form of chemical
  • concentrations as required
  • statement that it meets the requirements of both the AWWA and NSF/ANSI/CAN 60 Standards

Disinfection procedure:

• If disinfection using the Watermain Disinfection Procedure was required, refer to section 3 of the Watermain Disinfection Procedure for required documentation.
• If disinfection using the Water Storage Facility Disinfection Procedure was required, refer to section 5.2 of the Water Storage Facility Disinfection Procedure for required documentation.
• Statement whether a chlorine meter was used to measure chlorine residual concentrations used for disinfection. If the concentrations were calculated, reason why it was impractical to use a chlorine meter.
• If water was discharged to the natural environment:
  • description of handling of disinfection water
  • if dechlorination was required, total chlorine residual concentration of water discharged after dechlorination and name of chemical used for dechlorination
  • statement whether discharge met the requirements of Condition 5.5 of Schedule B of the Municipal Drinking Water Licence, including which sub-clause of Condition 5.5 was met

For disinfection of filters other than cartridge filters:

• Initial and final chlorine concentration results, including locations of samples.
• Date and time disinfection started and ended with calculation of retention period(s) in minutes or hours.
• Statement that filter walls above normal operating water level were disinfected by spraying all surfaces that may come in contact with water with a minimum 200 mg/L chlorine solution. For GAC and membrane filters, statement that the spraying of filter walls occurred prior to adding the GAC or membranes to the filter basins.
• When GAC is added to a filter, statement that sanitary practices were used when storing, handling and installing the GAC.

For disinfection of cartridge filters:

• Statement that the new or temporarily removed filter cartridge was stored, handled and installed using sanitary practices prior to placing into service.
• Statement that filter housing was cleaned as per section 4.1 of AWWA C653.
• Statement that the process water filter housing was disinfected by 1 of the following methods:
  • spraying all surfaces that come in contact with water with a minimum 1% chlorine solution
  • filling the filter housing with a chlorine solution, including concentration of chlorine solution and date/time disinfection started and ended with calculation of retention period(s) in minutes or hours

For polymer-based membranes:

• Statement that membranes were stored, handled, installed, and repaired using sanitary practices
• If deemed appropriate by the operating authority, statement that membranes were flushed
• If required, statement that membranes underwent maintenance cleaning prior to placing into service

For disinfection of water pumps:

• Statement that pump was cleaned or flushed.
• Statement that the process water or drinking water pump was disinfected by 1 of the following methods:
  • spraying all surfaces that come in contact with water with a minimum 1% chlorine solution
  • filling the pump with a chlorine solution, including concentration of chlorine solution, dates and times disinfection started and ended with calculation of retention period(s) in minutes or hours

For UV units:

• Statement that sanitary practices were maintained
• If applicable, statement that the UV unit was disinfected as per manufacturer’s recommendations

Microbiological sampling:

• Date, time and location of microbiological samples
• Microbiological sample and applicable chlorine residual concentration test results
• If applicable, name of certified operator or water quality analyst who took the microbiological samples and associated chlorine concentration residual tests

Placing into service:

• Date and time of placing into service.
• Statement that sanitary practices were maintained following disinfection until the component was placed into service.
• If applicable, when a component was placed into service:
  • chlorine residual concentration test result(s)
  • date, time and location of the test(s)
• If no microbiological samples were taken after disinfection of a water pump or a cartridge filter, name of certified operator who witnessed the disinfection.
• For a GAC filter, statement that microbiological samples were taken prior to adding the GAC.
• If a filter was left empty more than 5 days after being disinfected, statement that satisfactory microbiological sample results were received prior to placing the filter into service.
• If a process water filter was not placed into service within 5 days after being filled after disinfection, statement that, prior to placing the filter into service:
  • the filter effluent turbidity was below 1.0 NTU
  • the filter contents were deemed fit to be directed to the next treatment process
• Exception as per section 5.1.7 – Placing component into service prior to receiving microbiological sample test results:
  • description of the circumstances requiring the early placing into service prior to receiving microbiological sample test results
  • name of Operator-in-Charge who verified that the cleaning and disinfection of the component met the requirements of this procedure

6. Delivery

No modification to this section.

Appendix A - Definitions

Appurtenance

means an appurtenance, within the meaning of O. Reg. 170/03, that is in contact with water.

AWWA C653

means ANSI/AWWA Standard C653 - “Disinfection of Water Treatment Plants”, Version 2020, as updated.

Certified operator

means certified operator within the meaning of O. Reg. 170/03.

Chlorine meter

means a calibrated electronic direct readout colourimetric or amperometric chlorine meter that has a readout that displays to at least 2 significant figures. Another method may be approved by the Director.

Component

means a part of a drinking water system that is normally in contact with raw water, process water or drinking water.

Contaminant

means foreign matter that is not intended to enter drinking water.

Contaminated/contamination

means the presence of a contaminant in drinking water.

Director

means a Director appointed pursuant to section 6 of the Safe Drinking Water Act (SDWA) for the purposes of Parts V/VI of the Act.

Disinfected/disinfection

means a process that inactivates pathogenic microorganisms on the surfaces of system components in contact with water by chemical oxidants or equivalent agents. This definition does not include “primary disinfection” based on log removal/inactivation credits.

Drinking water

means drinking water within the meaning of the Safe Drinking Water Act (SDWA).

Drinking water pump

means a pump that directs drinking water to users through the distribution system.

Drinking water system

means drinking water system within the meaning of the Safe Drinking Water Act (SDWA).

Isolate/isolation

means operate valves to ensure that there is no flow of water to or from a specific section of a water treatment plant or component and/or its associated piping.

Log removal/inactivation credit

means a value assigned to a unit treatment process used to achieve “primary disinfection”, expressed in logarithmic units, for the removal or inactivation of a specific pathogen or group of pathogens, such as viruses, bacteria and protozoa.

Microbiological sample

means water sample taken and tested for Escherichia coli and total coliforms by a licensed and accredited laboratory.

Ministry

means Ontario’s Ministry of the Environment, Conservation and Parks.

Operating authority

means operating authority within the meaning of the Safe Drinking Water Act (SDWA).

Operator-in-Charge

means an operator-in-charge within the meaning of O. Reg. 128/04.

Pipe/piping

means any pipe or conduit that conveys water, inside a building or underground.

Potable water in AWWA C653

means drinking water.

Pressure vessel

means an enclosed vessel an enclosed vessel containing raw, process or drinking water that is pressurized during normal operation.

Process water

means water that is in the process of being treated in a water treatment plant. This means, after the point where log removal/inactivation credit treatment has started, but before all log removal/inactivation credit treatment has been achieved.

Process water pump

means a pump that conveys process water or drinking water that is not being directed to users. Examples of such drinking water pumps are backwash pumps that convey treated water.

Raw water

means water before the point where log removal/inactivation credit treatment starts.

Satisfactory

means

• as related to drinking water, microbiological sample results that are negative for Escherichia coli and total coliforms
• as related to raw or process water, microbiological sample results acceptable to the operating authority

Storage facility

means any tank, reservoir, elevated tank, standpipe or pressure vessel that contains drinking water or process water, other than filter basins.

Tank

means any clearwell and any tank (including any tank within the water treatment plant process and pressure/surge tank that is bladderless). Tank does not include filter basins.

Treated water

means water inside the water treatment plant after the point where log removal/inactivation credit treatment has been completed.

Water quality analyst

means a water quality analyst within the meaning of O. Reg. 128/04.

Water Storage Facility Disinfection Procedure

means any future “Water Storage Facility Disinfection Procedure” published by the ministry, as amended.

Watermain Disinfection Procedure

means the ministry’s “Watermain Disinfection Procedure”, dated August 1, 2020, as amended.

Municipal Drinking Water Well Disinfection Procedure

means any future “Municipal Drinking Water Well Disinfection Procedure” published by the ministry, as amended.

Appendix B - Version history

Contact us

For more information, you can contact the Client Services and Permissions Branch at:

• Tel: 1-866-793-2588 - Monday to Friday, 9 a.m. to 5 p.m.
• email: mdwlp@ontario.ca