⭐ Upgrade to Pro - £19
Unlock all lessons and mock exams to pass Level 2 + Level 3 theory exams.
Upgrade nowNon-Mechanical Backflow Prevention (Air Gaps)
Read through the material below, then test your understanding.
Module Lessons
Cold Water
Incoming Mains: Communication vs. Supply Pipes
Installation Depths and Building Entry
Direct Cold Water Systems
Indirect Cold Water Systems
Siting and Installing Storage Cisterns
Float-Operated Valves and Overflows
Principles of Backflow
Terminal Fittings and Taps
Non-Mechanical Backflow Prevention (Air Gaps)
Water Treatment and Distribution
Mechanical Backflow Prevention Valves
Commissioning: Testing and Flushing
Lesson Overview
Non-mechanical backflow prevention relies on physical air gaps between wholesome water outlets and contaminated water levels to prevent back siphonage and backflow without using moving parts.
Learning Objectives
Identify the key types of non-mechanical air gaps and their fluid category ratings.
Calculate and apply the correct tap gap distances for domestic appliances and kitchen sinks.
Explain the operational and installation requirements of specialised non-mechanical devices including pipe interrupters.
Unlock the full lesson & knowledge check
Get lifetime access to every Level 2 & 3 lesson, 3500+ total questions, and timed City & Guilds mock exams.
Get Pro Access (£19)Already have Pro? Sign in
Interactive City & Guilds Level 2 and Level 3 plumbing lessons, flashcards and mock exams, built for UK students and professionals.
© 2026 PlumbingIQ. All rights reserved.