Visual inspection is walking the entire pipe route on a regular schedule and looking for wet spots, patches of unusually green growth, erosion and sinking ground, and in winter for spots where frost has melted above the pipe. Check the tank, valves, air vents, drain points and standpipes on the same walk, and write down what you find so changes show up over time.
Part of Water Distribution
Visual inspection is the cheapest leak detection method there is: a person walking the pipeline, observing the ground and the fittings. It finds the small problems before they become failures.
Leaks Show On The Surface Before They Show At The Tap
Water escaping from a buried pipe finds its way upward or sideways. It softens the ground, feeds plants that grow greener or faster along the line, and can wash out soil so that the surface sags or gullies open. In freezing weather, leaked water that comes from the ground or a warmer source can melt the frost above the line.
What You Need
- The network map, with every valve, vent, drain point and tap marked
- A notebook, and a stick or small spade
- Spare fittings and tools to fix small problems on the spot
- A second person on long or steep routes, for safety
- A schedule: the same route at agreed intervals, after heavy rain, and after any freeze
Method: Walk The Line In Order
Step 1: Start at the source or tank. Check the lid, vent screen, overflow and float valve.
Step 2: Follow the pipe. Look for wet or boggy spots, green patches, erosion, subsidence, exposed pipe, and animal damage.
Step 3: Check each fitting: valve boxes (clear and findable), air vents, drain points, and joints.
Step 4: Check each standpipe: pad intact, drain flowing, tap not dripping, no pooling.
Step 5: Look for cross-connections: anything that links the drinking-water pipe to another source or a waste line.
Step 6: Record what you saw and where. Mark a wet spot on the map.
Step 7: Act: repair small faults now, and send bigger ones to a leak detection test.
Worked Example
If a night test shows 24% loss and a wet patch has appeared 120 m below the tank, close the valves to isolate the section containing the patch and see whether the flow from the tank outlet stops. If it does, the leak is in that section and the patch marks the place to dig.
Common Mistakes
- Walking only the easy parts of the route. Leaks hide where access is hard.
- No record. A change over months is invisible without notes.
- Digging while the line is pressurised. Close the valves first.
- Ignoring small dampness. It is the early warning.
Safety
Slopes, gullies and wet ground
Inspect steep, eroded routes with a partner and good footwear, and never stand in a trench or gully beside an unexplained leak: undermined ground can give way.
What’s Next
- Learn next: Leak Detection — measuring and locating the loss
- Combine with: Winterization — what to look for in freezing weather