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Sanitary and Rainwater Drainage Design: BS EN 12056

Key areas
Course content
Learning outcomes
Who should attend
Course timings
Course Fees
Upcoming courses

Key areas

  • An overview of previous Standards
  • Explanation of terminology within BS 12056, and comparisons with the Approved Document H
  • Sanitary design criteria
  • Sanitary design flow calculations and pipe sizing
  • Calculation of rainwater catchment areas and design flows
  • Eaves gutter sizing, rainwater pipe sizing and flat roof drainage calculations
  • Use of weir flow calculations

Course Content

This course will cover the application of BS EN 12056 for the design of above ground gravity drainage systems, including reference to Approved Document H. Example calculations to solve realistic design scenarios will also be included.

Session 1 - Sanitary Design Theory:

  • Background of sanitary standards
  • Format, terminology and definitions within BS EN 12056
  • Comparisons with other standards and Approved Document H
  • Types of ventilation for discharge stacks
  • Design limits for discharge branch pipes
  • System design criteria

Session 2 - Sanitary Design Application:

  • Calculation of basic design flow for sizing primary and secondary Ventilated stacks
  • Calculating design flow for mixed occupancy loads
  • Critical examination of frequency and discharge flow criteria

Session 3 - Rainwater Design Theory:

  • Background of rainwater standards
  • Sustainable design solutions
  • Product flow testing
  • Effective catchment area theory
  • Design considerations for eaves gutters
  • Comparisons with other standards and Approved Document H
  • Applying risk categories and selecting rainfall design rates
  • Sizing vertical and horizontal rainwater pipes

Session 4 - Rainwater Design Application:

  • Calculation of design flow for the sizing, eaves gutters and flat roof outlets
  • Parapet chutes, hopper heads and rainwater pipes
  • Conclusion

Learning Outcomes

  • Explain the background of sanitary Standards
  • Describe the format and application of the UK Regulations
  • Describe the format of BS EN 12056
  • Explain the terminology and classifications used within BS 12056
  • Differentiate between BS EN 12056 and the Approved Document H
  • Size sanitary stacks and branch pipes
  • Calculate the rainwater flow rate from catchment areas
  • Size eaves gutters and rainwater pipes
  • Determine the drainage requirements for flat roofs
  • Use weir flow calculations

Who Should Attend

This course is designed for people with limited knowledge of above ground drainage systems who would like to be more confident in their design, and will therefore be principally suited to new entrants into the field of public health engineering and mechanical engineers wishing to broaden their knowledge.

Course timings

Registration and coffee will be at 09.30
Course will start at 10.00 and finish at 16.30


Members Rate: £336 (£280 ex VAT)

Standard Rate: £372 (£310 ex VAT)


Upcoming courses


In-house training at your site

Training multiple staff at once is the most cost effective way to develop staff for organisations. All our courses can be delivered at your site (min 6 staff) at discounted rates. These In-House courses are only available in the UK and Europe. For an In-house quote please email; 
Name of course, approximate number of staff and your site address 


To contact the CIBSE Training Team with a query please

Email: or call: +44 (0)20 8772 3637