Chapter 6: Domestic water systems

6.1 General

• 6.1.1 For the purpose of this Standard, domestic water systems include both hot and cold potable water systems.
• 6.1.2 The proper design and operation of the domestic water system is essential for Legionella control.
• 6.1.3 Legionella bacteria proliferate most rapidly in the 25 – 42 °C temperature range.
• 6.1.4 Below 20 °C, the bacteria are dormant but still viable; the bacteria do not survive at temperatures above 49 °C, and maximum bacterial growth occurs at a temperature of 42 °C.
• 6.1.5 Provide access for ease of maintenance in all new systems.
• 6.1.6 All new piping systems shall be designed to prevent water stagnation. If, due to system design and operation, water stagnation cannot be avoided, provide means to periodically flush the piping system automatically.
• 6.1.7 Natural rubber, silicone, or Polyvinyl Chloride (PVC) pipe shall not be used in new systems, as these materials may contribute nutrients for the growth of bacteria.
• 6.1.8 In new hot and cold water systems, piping between the faucet and the circulating mains shall be as stated in Table 6.1.

• 6.1.9 All new domestic water piping systems shall be installed with suitable backflow prevention devices to separate the domestic water systems from non-potable water systems in the building.

6.2 Cold water systems

Design requirements

• 6.2.1 This section applies to new equipment and to major upgrades to existing equipment.
• 6.2.2 Cold water temperatures shall be maintained below 20 °C.
• 6.2.3 When designing a distribution pipe system, consider that growth of Legionella may occur in low-flow or under-used sections of a pipe distribution system.
• 6.2.4 Areas at risk include drinking fountains, dead-end lines, attached hoses, shower nozzles, tap faucets, and hot water tanks/reservoirs.
• 6.2.5 Design and locate water circulation pumps in a manner that enables the stated water temperatures to be maintained.
• 6.2.6 Water distribution systems should be constructed using copper piping.
• 6.2.7 To eliminate stagnant water in piping systems, avoid long piping runs.
• 6.2.8 Locate cold water piping below hot pipes to minimize the potential for warming up due to convection.

Operation and maintenance

Inspection

• 6.2.9 Inspect system for the presence of pipes serving fixtures that experience periods of prolonged water stagnation at water temperatures between 20 and 50 degrees Celsius at least every 5 years.
• 6.2.10 Operate and maintain the potable water treatment equipment serving the building, where present, in accordance with prescribed federal and provincial/territorial requirements for drinking water quality.
• 6.2.11 Inspect drinking fountain for signs of microbial growth at least annually.

Disinfection

• 6.2.12 If a potable water system is suspected as the source of Legionella bacteria, a mechanical system inspection shall be conducted.
• 6.2.13 When an outbreak of Legionellosis has been associated with a potable water system, when suspected cases of the disease occur or bacterial testing results indicate a need, disinfection shall be performed.
• 6.2.14 The recommended method of disinfection for cold potable water systems shall be the use of a hyper-chlorination procedure as follows:
  • 6.2.14.1 Add an approved drinking water product in accordance with the use directions for the supplier of the product.
  • 6.2.14.2 All outlets shall be flushed until chlorine concentration at representative taps and faucets is confirmed by measurement and documented.
  • 6.2.14.3 Close all outlets and disinfect with chlorine for a minimum of 2 hours, but not exceeding 24 hours then thoroughly flush all outlets.
  • 6.2.14.4 Measure chlorine concentration at representative outlets to confirm it is within regulated limits before reuse of the system.

Minimum bacterial testing requirements

• 6.2.15 Perform a monthly total residual oxidant test on the building's incoming domestic water supply in accordance with federal and provincial/territorial requirements for drinking water quality, if the building is not fed by a municipally treated water supply or if concerns have been identified with the municipally treated water supply for the building.

6.3 Operation, maintenance and testing schedule for cold water systems

• 6.3.1 Table 6.2 below indicates a summary of the minimum frequency for operation, maintenance and testing requirements of cold water systems.

6.4 Hot water systems

Design requirements

• 6.4.1 This section applies to new equipment and to major upgrades to existing equipment.
• 6.4.2 Hot water shall be maintained or stored above 60 °C, distributed to each outlet at a minimum of 50 °C and reduced to below 43 °C at the point of use.
• 6.4.3 Do not oversize water storage tanks as this may result in improper water circulation.
• 6.4.4 Storage tanks shall have no pockets from which scale, sediment, and sludge would be difficult to remove.
• 6.4.5 Consider the use of instantaneous water heaters, either as standalone devices or in conjunction with storage heaters.
• 6.4.6 The storage tanks shall be designed to permit sterilization at a temperature of at least 75 °C.

Start-up and commissioning

• 6.4.7 Before any domestic hot water storage tank or heater is commissioned, it shall be sterilized by maintaining a minimum temperature of 70 °C for a period of not less than 48 hours.
• 6.4.8 Before any domestic hot water system is commissioned, it shall be thoroughly flushed out and the disinfected. The recommend disinfection method is the use of a chlorine-producing agent with a residual of at least 2 ppm for 24 hours, followed by thorough flushing of the system.

Operation and maintenance

• 6.4.9 Verify and record hot water storage tank temperature monthly for systems that are connected to shower facilities (including emergency showers). Follow the bacterial testing protocols of clause 6.4.19 when tank temperature is below 50 °C. Follow the requirements of clause 6.4.24.1 when the tank temperature is between 50 and 60 degrees Celsius. A domestic hot water system shall not be operated at a temperature that can cause scalding unless suitable protection measures are in place. Verify and record hot water storage tank temperatures annually for systems that serve multiple areas in the building and are not connected to showers.
• 6.4.10 Drain, flush and clean hot water storage tank at least annually for systems that serve multiple areas in the building and/or those that are connected to shower facilities.

Disinfection

• 6.4.11 Perform disinfection when indicated by the bacterial test results or the potable water source is suspected as a source of legionella bacteria.
• 6.4.12 The recommended methods of disinfection of hot water systems include the thermal shock treatment method or the hyper-chlorination method.
• 6.4.13 Thermal shock treatment method:
  • 6.4.13.1 Municipal building and sanitary codes shall be followed.
  • 6.4.13.2 Maintain the storage tank water temperatures at a minimum of 70 °C for 24 hours while progressively flushing each outlet in the system for at least 20 minutes.
• 6.4.14 Hyper-chlorination, method:
  • 6.4.14.1 An approved drinking water product shall be added in accordance with use directions for the supplier of the product.
  • 6.4.14.2 All outlets shall be flushed until chlorine concentration at representative outlets is confirmed by measurement and documented.
  • 6.4.14.3 Close all outlets and disinfect with chlorine for a minimum of 2 hours, but not to exceeding 24 hours then thoroughly flush all outlets.
  • 6.4.14.4 Measure chlorine concentration at representative outlets to confirm it is within federal/provincial/territorial limits before reuse of the system.

Minimum bacterial testing requirements

Water sampling locations

• 6.4.15 Water sampling locations for bacterial testing shall be in accordance with the facility Legionella Bacteria Control Management Program (LBCMP).
• 6.4.16 The facility LBCMP should consider, at a minimum, the following locations for water sampling;
  • 6.4.16.1 Most remote shower facilities

Bacterial testing results

• 6.4.17 Record the bacterial testing results on the facility LBCMP testing form (LBCMP-4).
• 6.4.18 Report the bacterial testing results in accordance with the regional and national reporting protocols.

Minimum bacterial testing requirements and frequency (normal operation)

• 6.4.19 Where the domestic hot water storage tank temperature is found to be below 50 °C in systems connected to showers, perform monthly dipslide tests of the domestic hot water storage tank(s) to determine the total bacteria count (TBC). Refer to Figure 4: Hot water systems bacterial test protocol normal mode located in Appendix D.
• 6.4.20 Perform Legionella bacteria culture tests to identify, total Legionella pneumophila including all serogroups (LPTOT) bacteria levels (Refer to Figure 4: Hot water systems bacterial test protocol normal mode located in Appendix D).
  • 6.4.20.1 Every six months from the locations identified in clause 6.4.16.
  • 6.4.20.2 Annually, at the most remote fixture, for systems with a storage temperature below 50 °C that serve multiple areas in a building and are not connected to showers.

Minimum bacterial testing requirements (emergency mode)

• 6.4.21 Use the emergency-mode bacterial test procedure if:
  • 6.4.21.1 There have been multiple reported cases of Legionnaires' disease in the past 30 days in the region within a 10 km radius of the building location and/or,
  • 6.4.21.2 The building has had recurring Legionella bacteria levels detected by the Legionella bacteria culture test that required disinfection of the system within the past 90 days and/or,
  • 6.4.21.3 Regional Health authorities direct more stringent bacterial testing.
• 6.4.22 Unless directed otherwise by the regional health authority, or due to regional restrictions, a weekly qPCR test should be performed to obtain rapid, Legionella specific results, to determine the Legionella Pneumophila bacteria count at each water sampling location.

Dipslide testing limits and actions

• 6.4.23 (Level D1—Green)—When the TBC is less than 1,000 cfu:
  • 6.4.23.1 Continue with normal O&M.
• 6.4.24 (Level D2—Yellow)—When TBC is greater than or equal to 1,000 and less than or equal to 10,000 cfu:
  • 6.4.24.1 Review and adjust the O&M procedures and adjust the storage tank temperature to 60 °C where the system is equipped with measure to prevent scalding at the point of use.
  • 6.4.24.2 Continue operation with adjusted O&M and storage tank temperature.
• 6.4.25 (Level D3—Orange)—When TBC exceeds 10,000 cfu:
  • 6.4.25.1 Disinfect the system and flush the tank within 48 hours and maintain tank temperature at a minimum of 50 °C until tank flushing and system disinfection. Flush the storage tank in accordance with manufacturer’s recommendations and disinfect the system before putting it back into service.
  • 6.4.25.2 Review and adjust the O&M procedures and adjust the storage tank temperature to 60 °C where the system is equipped with measures to prevent scalding at the point of use.
  • 6.4.25.3 Continue operation with adjusted O&M and storage tank temperature.
  • 6.4.25.4 Wait 2 to 7 days then perform a Legionella bacteria culture test in accordance with clauses 6.4.26 through 6.4.30 below.

Legionella bacteria culture testing limits and actions

• 6.4.26 Perform Legionella bacteria culture test in accordance with ISO 11731-1998 and ISO/TS 11731-2-2004.
• 6.4.27 Where the analysis result indicates interfering flora are present that may have affected the results:
  • 6.4.27.1 Disinfect the system and flush the tank within 48 hours and maintain tank temperature at a minimum of 50 °C until tank flushing and system disinfection. Flush the storage tank in accordance with manufacturer’s recommendations and disinfect the system before putting it back into service.
  • 6.4.27.2 Review and adjust the O&M procedures and the water treatment program as required to ensure acceptable bacterial levels in the system.
  • 6.4.27.3 Wait 2 to 7 days then perform a Legionella bacteria culture test in accordance with clauses 6.4.26 through 6.4.30.
• 6.4.28 (Level C1—Green)—When the LPTOT count is less than 10 cfu/mL:
  • 6.4.28.1 Continue with normal O&M.
• 6.4.29 (Level C2—Orange)—When the LPTOT count is greater than or equal to 10 and less than or equal to 100 cfu/mL:
  • 6.4.29.1 Disinfect the system and flush the tank within 48 hours and maintain tank temperature at a minimum of 50 °C until tank flushing and system disinfection. Flush the storage tank in accordance with manufacturer’s recommendations and disinfect the system before putting it back into service.
  • 6.4.29.2 Review and adjust the O&M procedures and adjust the storage tank temperature to 60 °C where the system is equipped with measure to prevent scalding at the point of use.
  • 6.4.29.3 Continue operation with adjusted O&M and storage tank temperature.
  • 6.4.29.4 Wait 24 hours then perform a qPCR test in accordance with clauses 6.4.31 through 6.4.34.
• 6.4.30 (Level C3—Red)—When the LPTOT exceeds 100 cfu/mL:
  • 6.4.30.1 Immediately implement measures that will eliminate water dispersion by aerosol then clean the storage tank in accordance with manufacturer’s recommendations and disinfect the system before putting it back into service.
  • 6.4.30.2 Review and adjust the O&M procedures and adjust the storage tank temperature to 60 °C where the system is equipped with measures to prevent scalding at the point of use.
  • 6.4.30.3 Continue operation with adjusted O&M and storage tank temperature.
  • 6.4.30.4 Wait 24 hours then perform a qPCR test in accordance with clauses 6.4.31 through 6.4.34.

Quantitative polymerase chain reaction testing limits and actions

• 6.4.31 Perform qPCR Test in accordance with ISO/TS 12869
• 6.4.32 (Level Q1—Green)—When the Legionella pneumophila bacteria count is less than 10 GE/mL:
  • 6.4.32.1 Continue with normal O&M.
  • 6.4.32.2 Wait 2 to 7 days then perform a Legionella bacteria culture test in accordance with clauses 6.4.26 through 6.4.30.
• 6.4.33 (Level Q2—Yellow)—When the Legionella pneumophila bacteria count is between 10 and 100 GE/mL:
  • 6.4.33.1 Review and adjust the O&M adjust the storage tank temperature to 60 °C where the system is equipped with measures to prevent scalding at the point of use.
  • 6.4.33.2 Continue operation with adjusted O&M and storage tank temperature.
  • 6.4.33.3 Wait 2 to 7 days then perform a Legionella bacteria culture test in accordance with clauses 6.4.26 through 6.4.30.
• 6.4.34 (Level Q3—Orange)—When the Legionella pneumophila bacteria count exceeds 100 GE/mL:
  • 6.4.34.1 Disinfect the system and flush the tank within 48 hours and maintain tank temperature at a minimum of 50 °C until tank flushing and system disinfection. Flush the storage tank in accordance with manufacturer’s recommendations and disinfect the system before putting it back into service.
  • 6.4.34.2 Review and adjust the O&M procedures and adjust the storage tank temperature to 60 °C where the system is equipped with measures to prevent scalding at the point of use.
  • 6.4.34.3 Continue operation with adjusted O&M and storage tank temperature.
  • 6.4.34.4 Wait 24 hours then perform a qPCR test in accordance with clauses 6.4.31 through 6.4.34.

6.5 Operation, maintenance and testing schedule for hot water systems

• 6.5.1 Table 6.3 below indicates a summary of the minimum frequency for operation, maintenance and testing requirements of hot water systems.