PART H · Drainage and waste disposal
Part H building regulations explained
Part H deals with drainage and waste disposal. It covers more than connecting a toilet to a pipe. A suitable design needs to carry wastewater and rainwater away safely, protect drains and allow access for maintenance.
What does Part H cover
The six requirements address foul water drainage, wastewater treatment and cesspools, rainwater drainage, building over sewers, separate drainage systems and solid waste storage.
Different projects engage different requirements. A rural house without a mains connection needs a different drainage assessment from an extension beside a public sewer.
Why should drainage be surveyed early
Existing drawings may not show the actual pipe routes or ownership. Establish where drains run, their condition and where they discharge before foundations and room layouts are finalised.
An extension can affect a drain even where no new toilet is proposed. It may build over a pipe, alter access or change the loads around it.
What should the design explain
Identify pipe routes, gradients, connections, ventilation where relevant and accessible maintenance points. Rainwater disposal should have a justified destination rather than an assumed connection to the nearest pipe.
For example, moving a kitchen to the opposite side of a house can make the waste route a design constraint, not merely a plumbing detail.
Does building control cover every permission
Building regulations approval does not replace any separate agreement required from a sewerage undertaker or settle rights over neighbouring land. Check those matters before construction.
What should be recorded
Keep the drainage layout, survey information, any undertaker agreement and relevant inspection or testing records. Mark maintenance access accurately in the final layout.
Do not conceal inspection points behind fixed cupboards or inaccessible finishes without an agreed solution. The system should remain maintainable after the building is occupied.