Section H5 Separate systems of drainage

  1. The Requirement
    1. Guidance

      The Requirement

      Requirement Separate systems of drainage H5. Any system for discharging water to a sewer which is provided pursuant to paragraph H3 shall be separate from that provided for the conveyance of foul water from the building. Limits on application Requirement H5 applies only to a system provided in connection with the erection or extension of a building where it is reasonably practicable for the system to discharge directly or indirectly to a sewer for the separate conveyance of surface water which is: (a) shown on a map of sewers; or (b) under construction either by the sewerage undertaker or by some other person (where the sewer is the subject of an agreement to make a declaration of vesting pursuant to Section 104 of the Water Industry Act 1991 (b)).  

      Guidance

      Performance In the Secretary of State’s view the requirements of H5 will be met if separate systems of drains and sewers are provided for foul water and rainwater where:

      a. the rainwater is not contaminated; and

      b. the drainage is to be connected either directly or indirectly to the public sewer system and either:

      i. the public sewer system in the area comprises separate systems for foul water and surface water; or

      ii. a system of sewers which provides for the separate conveyance of surface water is under construction either by the sewerage undertaker or by some other person (where the sewer is the subject of an agreement to make a declaration of vesting pursuant to Section 104 of the Water Industry Act 1991).

      Introduction to provisions 0.1 These provisions are to help minimise the volume of rainwater entering the public foul sewer system as this can overload the capacity of the sewer and cause flooding. Provision where separate sewer systems are provided 1.1 Where the buildings are to be drained to the public sewer system, and the sewerage undertaker has provided a separate system of sewers, separate drainage systems will be necessary in order to comply with the requirements of Section 106 (Right to communicate with public sewers) of the Water Industry Act 1991 (see appendix H1-C paragraph C.7). Provision where separate sewer systems are proposed 1.2 Separate foul and rainwater drainage systems should also be provided where there is a combined sewer system at present but a system of sewers which provides for the separate conveyance of surface water is under construction either by the sewerage undertaker or by some other person (where the sewer is the subject of an agreement to make declaration of vesting pursuant to Section 104 of the Water Industry Act 1991). 1.3 These separate drainage systems will both initially connect to the existing combined sewer system. However, when the separate sewer systems are completed, the drainage will be reconnected to the new sewers, minimising the disruption to the occupiers. Contaminated runoff 1.4 Approved Document H3 paragraph 3.21 deals with drainage from areas where materials are stored which could contaminate runoff. This could cause pollution if discharged to a surface water sewer. Where such flows are to be discharged into the foul sewer system, the consent of the sewerage undertaker should first be obtained in accordance with Section 106 (Right to communicate with public sewers) of the Water Industry Act 1991 (see appendix H1-C paragraph C.7). The sewerage undertaker should also be consulted where such flows are to be discharged into a foul drain which, though it would initially connect to a combined sewer, is intended would eventually be reconnected to a proposed foul sewer.

      • Diagram 1 Direct connection of ground Floor WC to a drain Part H1 Diagram 1 Direct connection of ground Floor WC to a drain Part H1
      • Diagram 2 Branch connection to stacks- crossflow prevention Part H Diagram 2 Branch connection to stacks- crossflow prevention Part H
      • Diagram 3 Branch Connections Part H Diagram 3 Branch Connections Part H1
      • Diagram 4 Branch ventilation pipes part H1 Diagram 4 Branch ventilation pipes part H1
      • Diagram 5 Stub stack Part H1 Diagram 5 Stub stack Part H1
      • Diagram 6 Termination of ventilation stacks or ventilation part of discharge Part H1 Diagram 6 Termination of ventilation stacks or ventilation part of discharge Part H1
      • Diagram 7 Pipes Penetrating walls Part H2 Diagram 7 Pipes Penetrating walls Part H1
      • Diagram 8 Pipe runs near buildings Part H2 Diagram 8 Pipe runs near buildings Part H1
      • Diagram 9 Discharge capacities of foul drains running 0.75 proportional depth Part H Diagram 9 Discharge capacities of foul drains running 0.75 proportional depth Part H1
      • Diagram 10 Bedding for pipes Part H Diagram 10 Bedding for pipes Part H1
      • Diagram 11 Protection for pipes laid in shallow depths (minimum sizes) Part H Diagram 11 Protection for pipes laid in shallow depths (minimum sizes) Part H1
      • Diagram 12 Joints for concrete encased pipes(minimum sizes) Part H Diagram 12 Joints for concrete encased pipes(minimum sizes) Part H1
      • Diagram 1 Drainage Field H2 Diagram 1 Drainage Field H2
      • Diagram 2 Drainage mound Part H2 Diagram 2 Drainage mound Part H2
      • Diagram 3 Typical horizontal flow reed bed treatment system Part H2 Diagram 3 Typical horizontal flow reed bed treatment system Part H2
      • Diagram 4 Typical flow reed bed treatment system Part H2 Diagram 4 Typical flow reed bed treatment system Part H2
      • Diagram 1 Rainfall intensities for design of gutter and rainfall pipes (litres per second per square metre) Part H3 Diagram 1 Rainfall intensities for design of gutter and rainfall pipes (litres per second per square metre) Part H3
      • Diagram 2 Rainfall intensities for design of drainage from paved areas and underground rainwater drainage (litres per second per square metre) Part H3 Diagram 2 Rainfall intensities for design of drainage from paved areas and underground rainwater drainage (litres per second per square metre) Part H3
      • Diagram 3 Discharge capacities of rainwater drains running full Part H3 Diagram 3 Discharge capacities of rainwater drains running full Part H3
      • Table 1 Minimum trap sizes and seal depths Part H1 Table 1 Minimum trap sizes and seal depths Part H1
      • Table 2 Common branch discharge pipes unventilated Part H Table 2 Common branch discharge pipes unventilated Part H1
      • Table 3 Minimum Diameters for discharge stacks Part H Table 3 Minimum Diameters for discharge stacks Part H1
      • Table 4 Materials for sanitary pipework Part H Table 4 Materials for sanitary pipework Part H1
      • Table 5 Flow rates from dwellings Part H Table 5 Flow rates from dwellings Part H1
      • Table 6 Recommended minimum gradients for foul drains Part H Table 6 Recommended minimum gradients for foul drains Part H1
      • Table 7 Materials for below ground gravity drainage Part H1 Table 7 Materials for below ground gravity drainage Part H1
      • Table 8 Limits of cover for class 120 clayware pipes in any width of trench Part H Table 8 Limits of cover for class 120 clayware pipes in any width of trench Part H1
      • Table 9 Limits of cover for class M concrete pipes in any width of trench Part H Table 9 Limits of cover for class M concrete pipes in any width of trench Part H1
      • Table 10 Limits of cover for thermoplastic (nominal ring stiffness SN4) pipes in any width of trench Part H Table 10 Limits of cover for thermoplastic (nominal ring stiffness SN4) pipes in any width of trench Part H1
      • Table 11 Minimum dimensions for access fittings and inspection chambers Part H Table 11 Minimum dimensions for access fittings and inspection chambers Part H1
      • Table 12 Minimum dimensions for manholes Part H Table 12 Minimum dimensions for manholes Part H1
      • Table 13 Maximum spacing for access points in metres Part H1 Table 13 Maximum spacing for access points in metres Part H1
      • Table 14 Materials for access points Part H1 Table 14 Materials for access points Part H1
      • Table A1 Flow rates from dwellings Part H Table A1 Flow rates from dwellings Appendix H1
      • Table A2 Flow rates from appliances Part H Table A2 Flow rates from appliances Appendix H1
      • Table A3 Minimum trap sizes and seal depths additional to Table 2 Part H Table A3 Minimum trap sizes and seal depths additional to Table 2 Appendix H1
      • Table C1 Characteristics that should be considered when designing or laying a shared drain:sewer so that it meets the basic requirements for adoption Part H Table C1 Characteristics that should be considered when designing or laying a shared drain:sewer so that it meets the basic requirements for adoption Appendix H1
      • Table 1 Calculation of drained area Part H Table 1 Calculation of drained area Part H3
      • Table 2 Gutter sizes and outlet sizes Part H Table 2 Gutter sizes and outlet sizes Part H3