Top 5 Plumbing Mistakes Builders Make (And How to Fix Them)

Plumbing installed correctly lasts decades. Installed incorrectly, it causes water damage, mould and costly repairs.

1. Wrong Pipe Grade

Using drainage-grade PVC for pressure supply is a common error. Use Class E or Class C pipes for mains pressure.

2. Inadequate Fall on Drainage

Drainage pipes need a minimum 1:40 gradient. Too flat and waste won't clear; too steep and solids block.

3. Not Pressure Testing Before Plastering

Test at 1.5× working pressure before closing walls. A leak found after plastering costs ten times more to fix.

4. Skipping Isolation Valves

Every appliance needs an isolation valve so you can service it without shutting off the whole building.

5. No Access Panels

Concealed pipes must have access panels at every joint — a maintenance and regulatory requirement.