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Sanitary and Rainwater Drainage Design: BS EN 12056

Upcoming Courses 
Key Areas  
Course Content
Learning Outcomes
Who Should Attend
Course Timings
Course Fees
In-House Training

A full overview and agenda, need to know information, and booking instructions can be found on the individual upcoming course pages. Click on a course below to view. 

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- Introductions
  • History of drainage design and standardisation

  • BS EN12056 Gravity drainage systems inside buildings – structure, concepts and terminology. EN 12056 – 1 (General and performance requirements)

  • Stack pressure profile, stack flow cross-section, offsets

  • The different Systems, square and swept entries, filling degrees, capacities

  • Alternative approaches to drainage eg Sovent, Vacuum, rifling

  • Discharge units and other design systems

Session 2 EN 12056-2 Sanitary pipework, layout and calculation
  • Calculation examples for a bathroom and kitchen

  • Calculations for a house, a flat, a block of flats etc

  • Selection of pipe size and ventilation options

Session 3 EN 12056-3 Roof drainage, layout and calculation
  • Rainfall in the UK, climate change

  • Stormwater and flooding issues

  • Hierarchy of disposal, SuDS, driveways

  • Limitations of EN 12056-3, balconies, syphonic systems, drainage chains, French drains

  • Gutters, parapets, overflows and off-sets

  • Simple calculations for ‘normal’ rainfall on a house

  • Calculations on 100 year storms and other ‘infrequent’ events.

  • Combined and separate drainage systems

Session 4 - The other parts of EN 12056 and legislation 
  • Problems with rainwater systems in real buildings

  • EN 12056 – 4 (Wastewater lifting plants. Layout and calculation),

  • EN 12056 -5 (Installation and testing, instructions for operation, maintenance and use)

  • UK Building Regulations and other relevant legislation

  • Quiz and questions

Learning Outcomes

  • Realise the scope of sanitary pipework and rainwater European Standards
  • Understand the history of above ground drainage standards
  • Understand the relationships between Standards, European Technical Approvals and English Building Regulations
  • Know the content and scope of all Parts of BS EN 12056
  • Understand air and water flow in stacks and branches - including filling degrees and Discharge Units
  • Understand the water flow in gutters and downpipes
  • Understand the calculations needed for pipe sizing and gutter sizing under various loads and situations  
  • Have an overview of sustainable drainage systems (SuDS) and Integrated Water Management (IWM)
  • Be able to identify drainage issues by observation
  • Have an insight into future drainage developments

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 will be at 09.30
Start Time: 10.00
Latest Finish: 5.00

Course Fees 

  • Members Rate: £336 (£280 ex VAT)
  • Standard Rate: £372 (£310 ex VAT)

In-house training at your site

Training multiple staff at once provides the opportunity for your organisation to have a training package crafted to your specific needs. In-house training can help your organisation overcome challenges and fill the skills gaps in your workforce. Courses run on a minimum number of six staff*.

For an In-house quote please email the following information to

  1. Name of course
  2. Approximate number of staff
  3. Your site address  

*Minimum numbers for In-house courses outside of the UK may vary

To contact the CIBSE Training Team with a query please

Email: or call: +44 (0)20 8772 3660