Drainage & Sanitation revision notes
Trap seals, branch pipework and stack ventilation, and keeping the system free of contamination.
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C&G Unit 207: Trap Seals, Waste Stacks & Soil Ventilation
Drainage terms glossary
Plain definitions of the above-ground drainage terms a Level 2 learner keeps meeting.
Foul drainage principles: traps and stacks
How traps, branch pipes, the soil stack and ventilation work together to carry foul water away and block smells.
Sanitary waste pipe sizes and length limits under Approved Document H
Maximum lengths and gradients for 32 mm, 40 mm, and 100 mm unvented waste branch runs.
Single-stack drainage and the trap seal
What the trap seal does, and what keeps it or breaks it on a single stack.
The single-stack system and stack ventilation
How a single-stack above-ground drainage system works and why the stack is ventilated.
Trap seal and branch pipe checklist
Things to check so a sanitary appliance drains properly and keeps its water seal against smells.
Traps and stack ventilation
Why every sanitary appliance has a trap and why stacks are ventilated.
Working out drain fall from a gradient (worked example)
Converting a gradient such as 1:40 over a pipe length into the actual vertical fall in millimetres.
Calculations: pipe fall & gradient
C&G Unit 207: Sanitary Appliances & Drainage Access
Read drainage questions from the appliance to the drain
Trace the waste route and identify where the trap seal is protected. Distinguish a blockage, poor fall and a ventilation problem instead of treating every drainage symptom as the same fault. Draw the arrangement before choosing an answer.
For calculation practice, use the drainage fall calculator to convert a stated gradient such as 1 in 40 into a fall over the given distance. Selecting the required gradient is a separate design decision. The plumbing hub connects this topic to the rest of your Level 2 revision.
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