WRAS revision notes
Keeping the supply safe — fluid categories and the backflow protection each one needs.
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- 4topics
Water Supply Regs 1999: Fluid Categories (1 to 5)
Water Supply Regs 1999: Backflow Prevention Devices
Air gaps as backflow protection
Choose the rated air-gap arrangement and preserve its inlet clearance, overflow capacity and separation.
Backflow protection and the five fluid categories
The five fluid categories and why the air gap gives the highest protection.
Backflow: back-pressure versus back-siphonage
The two ways contaminated water can flow the wrong way, and why an air gap is the safest break.
Choosing a backflow device for the fluid category
How the fluid category at an outlet decides which family of backflow protection is suitable.
Fluid categories and backflow protection
The five fluid categories and why backflow protection prevents contamination.
Matching backflow prevention devices to Fluid Categories
Match the fluid risk, possible form of backflow and complete installation to the device rating.
Water Fittings Regs 1999: Materials, Contamination & Stored Water
Water Fittings Regs 1999: Fluid Risk Categories
Practise Water Regulations questions from the hazard outward
Start a fluid-category question by identifying what the water could contact. Then consider the possible backflow route and the protection suitable for that installation. Recognising a valve name is not enough to establish that its arrangement protects the supply.
The Water Regulations guide works through this reasoning. If you are choosing a course, read how WRAS, Water Regulations and G3 differ; product approval and a person’s training are different matters. Cold-water practice helps reinforce the supply and storage principles.
In-depth guides for this module
Longer walkthroughs that sit alongside the revision notes.
Water Regulations revision guide: WRAS, fluid categories and backflow
Separate Water Regulations from WRAS product approval, then work through fluid categories 1–5, backflow risks and notification examples. Protection must suit the downstream hazard and the way backflow could occur.
Water Regulations, WRAS and G3: what plumbing learners should know
Water Regulations protect wholesome water, WRAS is mainly product approval, and G3 is the hot-water safety part learners meet around unvented systems.
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