Foreword
QCVN 07:2023/BXD was compiled by the Vietnam Association of Construction Environment, with professional coordination from the Department of Technical Infrastructure, submitted for appraisal by the Department of Science, Technology and Environment, appraised by the Ministry of Science and Technology, and issued by the Ministry of Construction under Circular No. 15/2023/TT-BXD dated December 29, 2023.
QCVN 07:2023/BXD replaces QCVN 07:2016/BXD which was issued under Circular No. 01/2016/TT-BXD dated February 1, 2016 by the Minister of Construction
QCVN 07-1:2023/BXD
NATIONAL TECHNICAL REGULATION ON TECHNICAL INFRASTRUCTURE SYSTEM – WATER SUPPLY WORKS
1 GENERAL PROVISIONS
1.1 Scope
1.1.1 This regulation stipulates the mandatory technical requirements and management requirements that must be complied with in the investment, construction, renovation, and upgrading of water supply works.
1.1.2 The provisions in this regulation are applied to:
– Surface water and groundwater exploitation works;
– Water treatment plants supplying water from exploitation works to treated water pumping stations;
– Piping networks, booster pumping stations, and auxiliary works on the network.
1.2 Applicable Entities
This regulation applies to all organizations and individuals with activities related to the investment, construction, renovation, and upgrading of water supply works.
1.3 Referenced Documents
The referenced documents below are essential for the application of this regulation. In cases where the referenced documents are amended, supplemented, or replaced, the latest versions shall apply.
QCVN 01:2021/BXD, National Technical Regulation on Construction Planning;
QCVN 07-3:2023/BXD, National Technical Regulation on Technical Infrastructure System – Works for Trenches and Technical Tunnels;
QCVN 40:2011/BTNMT, National Technical Regulation on Industrial Wastewater;
QCVN 50:2013/BTNMT, National Technical Regulation on Hazardous Waste Thresholds for Sludge from Water Treatment Processes;
QCVN 08-MT:2023/BTNMT, National Technical Regulation on Surface Water Quality;
QCVN 09-MT:2023/BTNMT, National Technical Regulation on Groundwater Quality;
QCVN 01-1:2018/BYT, National Technical Regulation on Domestic Water Quality.
1.4 Terms and Definitions
In this regulation, the following terms are understood as follows:
1.4.1
Water supply system
A collection of water exploitation works, pumping stations, water treatment plants, water factories, storage tanks, water towers, piping networks and auxiliary works to supply water with guaranteed quality, flow rate and pressure to water users.
1.4.2
Water exploitation works
Works that receive water from a water source into a collection tank or well to bring water to a treatment plant. In cases of large water level fluctuations, floating or sliding rail type water exploitation works are permitted.
1.4.3
Raw water pumping station
Works that pump water from exploitation works to water treatment plants.
1.4.4
Water treatment plant, water factory
A collection of works to treat water to meet the regulated quality requirements for clean water.
1.4.5
Treated water storage tank
Works that balance the inflow and outflow regimes, storing water for the treatment plant’s own use, the water factory, and firefighting water.
1.4.6
Treated water pumping station
Works that deliver treated water from storage tanks to the water supply network.
1.4.7
Water supply network
The piping network that distributes treated water from pumping stations to points of use, including primary, secondary, tertiary networks and related auxiliary works.
1.4.8
Raw water transmission pipeline
The pipeline that conveys water from raw water pumping stations to treatment plants or water factories.
1.4.9
Looped water supply network
A water supply network that delivers water to points of use from two directions, with pipes forming a closed loop.
1.4.10
Branched water supply network
A water supply network that delivers water to points of use from one direction, with pipes forming a branched shape (tree branches).
1.4.11
Primary network (transmission network)
Pipelines that have the function of transporting water to service areas of the water supply zone.
1.4.12
Secondary network (distribution network)
Connecting pipelines that have the function of balancing flows for primary network pipelines, ensuring safe operation of the water supply system and delivering to customers with large water use demands.
2 TECHNICAL PROVISIONS
2.1 General Requirements
2.1.1 Investment in constructing water supply systems must comply with the planning approved by competent authorities, ensuring the rational, safe and sustainable use of water sources in the context of climate change.
2.1.2 The structure and building materials of water supply works must ensure durability, stability throughout the design service life of the works under the impacts of natural conditions, environmental effects, and operational impacts. Chemicals, materials and equipment used in treatment, transmission and storage of domestic water must not affect water quality and human health.
2.1.3 The quality of treated water used for domestic purposes must meet the requirements of QCVN 01-1:2018/BYT and local regulations.
2.1.4 The capacity of the water supply system must be calculated for the day with the highest water demand in the year; domestic water must take into account the daily non-uniform usage factor; water for street flushing, landscaping, public works, commerce and services, special works, industry, leakage and the treatment plant’s own use must comply with QCVN 01:2021/BXD.
2.2 Water Sources
2.2.1 Raw water quality must meet the requirements of QCVN 08-MT:2023/BTNMT and QCVN 09-MT:2023/BTNMT. Other types of water sources such as brackish water are not subject to these regulations. In cases where the water source does not meet the requirements of QCVN 08-MT:2023/BTNMT and QCVN 09-MT:2023/BTNMT, that source is allowed to be used but treatment measures must be applied to ensure the treated water quality meets the provisions in 2.1.3.
2.2.2 Water sources must have sanitary protection conditions and sanitary protection zones to prevent contamination by domestic wastewater, industrial wastewater and other pollution risks.
2.2.3 Water sources for water treatment plants and water factories must comply with the relevant water use master plans approved by competent authorities, ensuring water source security and safety, having the ability to sufficiently supply the required water quantities for the planned water use stages, and must have adequate solutions to fully meet water use demands during the dry season.
2.3 Water Exploitation Works
2.3.1 Surface Water Exploitation Works
2.3.2.1 Surface water exploitation works must ensure:
– Sufficient design capacity for the project stages;
– Safe, stable, durable operation of the works; not affecting the hydrological regime of the water source and waterway transport;
– Consideration of rising sea levels and saltwater intrusion in coastal areas, lowering of water levels due to droughts and climate change impacts.
2.3.1.2 The location of surface water exploitation works must meet the following requirements:
– Must be located upstream of the flow relative to the water use areas according to the approved master plans. In cases where the flow direction cannot be determined or changes over time, or the water source is intruded by saltwater, the intake works location should be selected appropriately to ensure technical and economic conditions;
– Must be located in an area with good geological engineering conditions, avoiding the influence of other hydrological phenomena, having stable riverbanks and bed, minimally affected by erosion, sedimentation and flow changes, having sufficient necessary depth at the lowest water level to ensure long-term stability of the works;
– It is not permitted to locate the intake works downstream near hydropower plants. The minimum allowable distance is 1,000 m.
2.3.1.3 When constructing water exploitation works, the ability to flush, easily dredge mud and debris must be considered.
2.3.1.4 Water intake:
– Must ensure no surface vortex is created when taking in water; the minimum distance from the lowest water level to the top of the intake or throat is 0.5 m;
– Water intakes must not be constructed within the protection range of ship channels or areas with algae growth.
2.3.2 Drilled Wells for Groundwater Exploitation
2.3.2.1 Drilled wells for groundwater exploitation must ensure technical regulations, stability in yield, water quality and allowable drawdown during extraction, and must comply with legal provisions on groundwater exploitation.
2.3.2.2 The number of working wells is determined depending on the exploitation flow rate, the water supply capacity of the aquifer and the allowable drawdown. The number of backup wells is determined depending on the number of working wells and the water supply safety level.
2.3.2.3 The annular space between the casing pipes and between the casing pipe and the borehole wall must be sealed with clay or equivalent material to prevent surface water intrusion and contamination of the water source.
2.3.2.4 When a well is not in use, it must be plugged with impermeable material to ensure no contamination of the water source. In favorable geological conditions, water exploitation using buried slotted screen structures is allowed.
2.4 Pumping Stations
2.4.1 General Requirements
2.4.1.1 Pumping stations must be designed according to the specific characteristics of each type of station; consideration must be given to renovation and expansion according to the master plan.
2.4.1.2 The size of pumping stations must ensure the arrangement of working pumps, backup pumps, filter backwash pumps, air wash blowers, control equipment, piping, lifting equipment and operating space for installation and repair.
2.4.1.3 The underground portion of the pumping station must be constructed with impermeable materials. In case the walls of the pumping station are below the groundwater level, an impermeable layer must be applied to the bottom slab, inner and outer surfaces of the station walls.
2.4.1.4 Arrangement of Suction Pipes in Pumping Stations
The suction pipe of the pump must slope upwards towards the pump, and no points are allowed to cause air pockets anywhere on the suction pipe.
2.4.1.5 Arrangement of Discharge Pipes in Pumping Stations
Each pumping station must have at least 2 common discharge pipes, in which 1 pipe can be placed on standby for connection in a later stage. A single discharge pipe is allowed for stations with a capacity less than 10,000 m3/d or in systems with multiple pumping stations supplying water to the same network.
2.4.1.6 Lifting equipment must be arranged in the pump room. The type of lifting equipment is selected according to the weight of the largest pump set installed in the station.
2.4.2 Drilled Well Pumping Stations
2.4.2.1 The minimum floor area of a drilled well pumping station is 12 m2.
2.4.2.2 The station roof must have a pipe retrieval hatch.
2.4.2.3 Well pumping stations built in flood-prone areas must have the floor elevation of the pump room at least 0.5 m higher than the highest flood water level.
2.4.2.4 The well head must be at least 0.3 m above the floor.
2.4.2.5 There must be a drilled well with an installed pump serving as a reserve well. The reserve well must work alternately with the well group.
2.4.3 Raw Water Pumping Stations (surface water exploitation)
2.4.3.1 The design of raw water pumping stations must follow the equalization operating regime of the water treatment plant or water factory.
2.4.3.2 Raw water pumping stations supply raw water to the treatment plant or water factory, including domestic water pumps and backup pumps. When the intake works and pumping station are constructed in combination and in stages, the intake works and station building must be constructed for both stages right from the first phase, while the equipment installation is in accordance with each stage.
2.4.4 Treated Water Pumping Stations
2.4.4.1 Pumping stations must ensure safe and stable operation of the works in design cases; convenient for management, operation, maintenance and repair; have floors for arranging equipment serving management work; have ventilation and lighting systems; have solutions for transporting machinery and equipment; have water collection gutters, water collection pits and install pumps to drain leaked water.
2.4.4.2 In treated water pumping stations, arrange domestic water pumps, production water pumps, firefighting water pumps, and filter backwash pumps and air blowers are allowed.
2.4.4.3 Each pump group must have backup pumps. When firefighting pumps and domestic water pumps are of the same type, backup pumps can be selected in common for both pump groups.
2.4.4.4 The flow rate of domestic water pumps must ensure the water supply for the designed area during peak usage hours. The flow rate of firefighting pumps must provide sufficient domestic and firefighting water during peak usage hours when a fire occurs.
2.4.4.5 The pressure of the pumps must be determined based on the condition of ensuring a free pressure of 10 m at the most disadvantageous point of the network during peak hours and when a fire occurs during peak hours.
2.4.4.6 Treated water pumping stations of water supply stations and water factories with a capacity of 10,000 m3/d or more need to install frequency converters. The control of frequency converters must be automated according to the actual pressure on the network, the water pumping flow into the network, and the water level in the storage tank.
2.5 Water Treatment Plants, Water Factories
2.5.1 General Requirements
2.5.1.1 Each type of unit operation must have at least 2 units to ensure 24-hour equalization operation conditions with the ability to stop each work of the station for flushing and repair. For stations with a capacity below 3,000 m3/d, it is allowed to stop working for a few hours for flushing and repair, then it is allowed to build 1 unit.
2.5.1.2 Water treatment plants and water factories must be designed with a sludge treatment system for sedimentation tanks and filter backwash, or discharge into filter backwash sedimentation ponds, provided that the requirements of QCVN 40:2011/BTNMT and other environmental protection requirements are met.
2.5.2 Water Treatment Process Line
The process line for treating surface water and groundwater must be selected based on the composition and characteristics of raw water, the capacity scale of the water treatment plant or water factory, the treated water quality requirements for domestic use, production and other purposes as prescribed, ensuring requirements for efficient and economical energy use.
2.5.3 Reception and Degassing Compartments
2.5.3.1 The raw water reception and distribution compartment must ensure the full design capacity for the project’s approved stages.
2.5.3.2 A degassing compartment must be arranged when using a reaction tank with a suspended sludge layer, a sedimentation tank with a suspended sludge layer, and a contact filter tank.
2.5.4 Reaction-Flocculation Tank
In the water treatment process using coagulation chemicals, a mixing tank and a reaction tank must be arranged. In case it is necessary to use a water pipe from the reaction tank to the sedimentation tank, the water velocity in the pipe must not exceed 0.3 m/s.
2.5.5 Sedimentation Tanks
2.5.5.1 Pre-sedimentation tanks, pre-sedimentation ponds
Pre-sedimentation tanks or ponds must be built in case the water has a maximum suspended solids content greater than 1,000 mg/L. In case the land area conditions allow, building pre-sedimentation ponds with high water storage capacity to serve safe water supply when the water source has incidents or droughts is permitted, even when the maximum suspended solids content is less than 1,000 mg/L. The minimum water retention time is 1 day; when land conditions permit, calculate a longer retention time to serve safe water supply when the water source has incidents. A sludge discharge system for pre-sedimentation tanks and a sludge dredging measure for pre-sedimentation ponds must be designed.
2.5.5.2 Suspended solids concentration after sedimentation tank
2.5.5.2.1 The suspended solids concentration after leaving the sedimentation tank for a surface water source must not be greater than 20 mg/L.
2.5.5.2.2 In the groundwater treatment process, when the total suspended solids concentration after aeration is greater than 20 mg/L, a contact clarifier with sludge settling function must be calculated. The contact clarifier must be calculated with a minimum water retention time in the tank of 90 minutes when no coagulant is used. When the pH and alkalinity of the source water are high and there are effective settling aid solutions, or when lamella settlers are used, the minimum water retention time is allowed to be 60 minutes.
2.5.5.2.3 Sedimentation tanks must be designed with a sludge discharge system using hydrostatic pressure or pumps.
2.5.5.3 Pressure Flotation Tanks
2.5.5.3.1 Pressure flotation tanks are allowed to be used instead of sedimentation tanks in cases where the suspended solids content in the source water is low, the solids are in fine form, the reservoir water has a high color, the water source has algae, and in cases where economic and technical conditions allow.
2.5.5.3.2 The floating matter collection system on the surface must be designed so that when this system works, it does not affect the quality of water sent to the filter.
2.5.6 Filters
2.5.6.1 Rapid Gravity Filters
2.5.6.1.1 Rapid gravity filters must be calculated for 2 operating modes: normal operating mode and enhanced operating mode. In treatment plants with up to 20 filters, 1 filter must be expected to be stopped for repair; when the number of filters is greater than 20, 2 filters must be expected to be stopped for simultaneous repair.
2.5.6.1.2 A filter sand backwash system must be designed; the design parameters of the backwash system must be appropriate to ensure uniform and thorough cleaning of sand at all positions of the tank, avoiding sand loss during backwashing.
2.5.6.1.3 The size of pipes or troughs of the filter must be calculated according to the enhanced operating mode.
2.5.6.2 Membrane Filtration
2.5.6.2.1 Membrane filtration technology is allowed to be used to treat surface water, groundwater, brackish water, desalinate seawater, and filter ultra-pure water.
2.5.6.2.2 There must be a source water pretreatment measure before membrane filtration to reduce the load and prolong the working time of the membranes. Membranes with gradually decreasing sizes must be used before reverse osmosis (RO) filtration.
2.5.7 Iron and Manganese Removal from Water
2.5.7.1 Various contact materials are allowed to be used in manganese removal filters, provided that the contact materials do not harm human health and are permitted by inspection agencies. Chemicals can be used to remove manganese from water.
2.5.7.2 Iron Removal by Simple Aeration and Filtration
When the total iron content in water is less than 6 mg/L, Fe2+ accounts for 80% or more, the water source is not contaminated with NH4+, pH > 7, and other conditions allow, the technology of simple aeration and filtration using a water distribution system on the filter surface or overflow troughs before entering the filter is applicable.
2.5.7.3 Aeration by Sprinkler System
Sprinkler systems are allowed to be used in the technology of iron and manganese removal by aeration method in conditions without obstructing structures that block the wind flow.
2.5.7.4 Aeration by Air Blower
2.5.7.4.1 The design of air blowers must calculate the thickness of the contact material layer, and contact materials that cause clogging of the air blower must not be used. A backwash system for the contact material layer must be designed.
2.5.7.4.2 Blowers with appropriate flow rates must be selected to limit the formation of Fe(OH)3 precipitates right in the air blower.
2.5.7.5 Arsenic Removal from Water
2.5.7.5.1 Filter materials and contact materials used in arsenic treatment technology must not contain components that affect human health.
2.5.7.5.2 Filter materials and arsenic adsorption materials after disposal must be managed and treated as hazardous waste.
2.5.8 Sludge Treatment
2.5.8.1 Sludge from water treatment plants must be collected, dewatered, reused, or transported to waste treatment sites for treatment to ensure environmental sanitation safety as prescribed. Treatment of sludge from the water treatment process must meet the requirements of QCVN 50:2013/BTNMT.
2.5.8.2 Simple, effective sludge treatment technologies must be selected to ensure the quality of treated water can be reused in stations with a capacity of 5,000 m3/d or more, and fed into the first unit of the main treatment line of the water treatment plant or water factory.
2.5.9 Treated Water Storage Tanks
2.5.9.1 The capacity of treated water storage tanks in water treatment plants or water factories must be sufficient to equalize the flow between the amount of water flowing into the tank and the operating regime of the treated water pumping station, the amount of firefighting water for 3 hours of the urban area that the tank serves, the amount of water for the water supply station or water factory’s own use. The minimum tank capacity is 20% of the factory’s capacity. In case of using reservoir water for firefighting, the firefighting reserve water for the treated water storage tank is not calculated.
2.5.9.2 In the storage tank, there must be baffles to create a circulating water flow with a water retention time greater than 30 minutes, sufficient for the necessary contact time for disinfection (except for urban storage tanks if no chlorine is added to the tank).
2.5.10 Water Disinfection
2.5.10.1 The chemicals selected for disinfection must ensure high disinfection efficiency and safety for human health, including for operators of the disinfection system.
2.5.10.2 In the chemical storage house, labor protection equipment, ventilation systems, chlorine leak alarm devices, a neutralization system, or automatic chlorine absorption by chemicals in case of incidents must be equipped to ensure safety for operators, for all staff in the station and surrounding residents.
2.5.11 Other Conditions
2.5.11.1 Internal roads in water supply stations and water factories must have a minimum width of 3.5 m, sufficient to withstand the load of vehicles carrying the heaviest equipment in the station, and must have turning space for vehicles.
2.5.11.2 The power supply for water supply stations and water factories must be a priority power source. In the factory, backup generators must be equipped for water supply stations and water factories with reliability level I. The capacity of the backup generator must be sufficient for the main production works of the factory to operate.
2.6. Water Supply Network
2.6.1 Transmission Pipelines
2.6.1.1 Raw water transmission pipelines from the intake to the water factory and treated water pipelines from the water factory to the starting point of the distribution network must be designed with 2 pipelines and have connecting pipes. It must be ensured that when 1 pipe section in the system is damaged, 70% of the calculated flow can still be supplied.
2.6.1.2 The materials for transmission pipelines must ensure mechanical and chemical durability, withstand pressure and mechanical impacts, and not be destroyed under all working conditions.
2.6.1.3 There must be markers for the pipeline route and a safety corridor to avoid damaging the pipes during road expansion construction or other construction works.
2.6.2 Water Supply Pipelines
2.6.2.1 The water supply network of new urban areas must be placed in trenches or technical tunnels as prescribed in QCVN 07-3:2023/BXD.
2.6.2.2 The water supply pipeline network of grade III or higher urban areas must be divided into 3 levels. It is strictly forbidden to connect from the customer’s water pipes to the pipes of the primary or secondary network. Customers using 500 m3/d of water or more are allowed to connect to the secondary network.
2.6.2.3 The water supply pipeline network must be a looped network. A branched network is only allowed in the following cases:
– Production facilities are allowed to stop for repair;
– Water supply network for grade V urban areas or residential areas with a population below 3,000 people;
– According to the construction phases before the complete installation of the looped network according to the plan.
2.6.2.4 The minimum diameter of the domestic water supply network combined with outdoor firefighting in urban areas must be 100 mm.
2.6.2.5 Pipe materials must withstand pressure and mechanical impacts from heavy vehicles running on the road. The inner lining must ensure mechanical and chemical durability and not affect water quality or human health, and be permitted by health authorities. In case of laying pipes in corrosive soil or water areas, there must be anti-corrosion measures for the pipes.
2.6.2.6 On pressurized gravity pipes, energy-absorbing devices or other protective devices must be installed so that the pipes work within the allowable pressure range.
2.6.2.7 For non-pressurized gravity pipes, manholes must be built. If the terrain is too steep, step-changing wells must be built to reduce the water flow velocity.
2.6.2.8 The depth of underground pipe laying must be determined according to the load on the pipe crown, the durability of the pipe, the influence of the surrounding temperature and other conditions, but not less than 0.7 m from the ground surface to the pipe crown for pipe diameters less than or equal to 300 mm, not less than 1 m for pipe diameters greater than 300 mm. Pipelines passing through weak ground must be placed on pipe support structures to ensure no displacement and damage to joints.
NOTE: The minimum pipe laying depth is allowed to be reduced by 0.3 m compared to the above regulation when laying pipes on sidewalks, or when there are technical measures to protect the pipeline.
2.6.2.9 After installing each part of the network, a pressure test must be performed to check the tightness of the pipes and connectors. The test pressure is 1.5 times the working pressure of the pipeline. The pressure test procedure must comply with the national standard on pressure testing of water supply pipelines after installation.
2.6.3 Equipment for Monitoring and Ensuring Safe Water Supply
2.6.3.1 Discharge valves and air valves must be designed and installed at high points of the water supply network.
2.6.3.2 Sludge discharge valves must be designed and installed at the lowest points on each part of the network.
2.6.3.3 Water hammer must be calculated, and when necessary, water hammer prevention valves must be installed in pumping stations and water supply networks.
2.6.3.4 Devices for monitoring water quality at treatment plants, water factories, and monitoring turbidity and residual chlorine on transmission and distribution pipelines must be installed when the capacity is 10,000 m3/d or more.
2.6.4 Network Zoning and Separation
2.6.4.1 The water supply network of grade III or higher urban areas must be zoned and separated to reduce water loss. Zone meters and subzone meters must be installed.
2.6.4.2 Each subzone meter serves no more than 5,000 water customers; for special and grade I urban areas, it is allowed to serve up to 8,000 customers. Each zone meter includes 3 or more subzone meters.
2.6.5 Pipelines Crossing Rivers, Highways, and Railways
2.6.5.1 Underground pipelines crossing rivers (Dukes):
– The number of pipes crossing the riverbed must not be less than 2; the material for underground pipelines crossing rivers must be elastic and withstand pressure and mechanical impacts;
– The depth from the riverbed to the pipe crown must be determined according to the erosion conditions of the riverbed and the maximum load of ships passing on the river when anchoring does not cause damage to the pipeline crossing the river. The pipe backfill material must be gravel or crushed stone with a size of 20 mm to 40 mm. The minimum backfill depth is 0.5 m. There must be fixed anchors to prevent pipeline flotation;
– There must be inspection wells on both sides of the river and signboards for ships passing on the river.
2.6.5.2 Pipelines crossing highways and railways must be placed in a casing pipe. At both ends of the crossing pipe, there must be inspection wells, stop valves, and expansion joints.
2.6.6 Pressure Testing, Flushing, and Disinfection of Pipelines
2.6.6.1 Installed pipelines must be pressure tested according to technical standards. Before putting the water supply network into use, the network must be flushed with clean water.
2.6.6.2 After flushing the network, the network must be disinfected. After disinfection, the pipeline must be rinsed with clean water until the residual chlorine in the water does not exceed 1.0 mg/L.
2.6.7 Water Meters
2.6.7.1 On the water pipes leading to the point of use, water meters must be installed; there must be a stop valve before the meter. The opening and closing of the valve is only performed by the water supply network management unit.
2.6.7.2 Water meters must be installed at treated water pumping stations, at connection points between water supply stations, and at the beginning of secondary and tertiary network pipes.
2.6.7.3 Water customers must have water meters. The diameter of meters for households must not be larger than 15 mm, with a minimum accuracy class of B. In case of villas with swimming pools, 20 mm meters are allowed. Customers using 10 m3/d of water or more must select meters according to calculation. Water meters must be calibrated according to the provisions of the law on metrology.
2.7 Maintenance and Servicing
2.7.1 Water supply works and work items must be periodically maintained, serviced, or replaced to ensure the designed use functions.
2.7.2 The time of water supply interruption for pipeline repair, maintenance, or equipment replacement must not exceed 36 hours in a year (except in case of a transmission pipeline breakage incident).
2.7.3 The time of water supply interruption for flushing the pipelines of each network area must not exceed 8 hours.
3 IMPLEMENTATION ORGANIZATION
3.1 Transitional Provisions
3.1.1 Investment projects that have been approved before the effective date of this regulation shall continue to be implemented according to the provisions at the time of approval; the investment decision maker has the right to choose to apply this regulation.
3.1.2 Investment projects approved from the effective date of this regulation shall be implemented according to the provisions of this regulation.
3.2 State management agencies for construction in localities have the responsibility to organize the inspection of compliance with this regulation in the formulation, appraisal, approval and management of construction design.
3.3 The Ministry of Construction has the responsibility to disseminate and guide the application of this regulation to relevant entities. During the implementation of this regulation, if there are any problems, all opinions should be sent to the Department of Technical Infrastructure of the Ministry of Construction for guidance and handling.
