How do I choose between different pipeline inspection services for a utility with a large, aging distribution network?

Choosing the right pipeline inspection service for a large, aging utility distribution network comes down to matching the inspection method to the assets, risks, and decisions you need to support.

1) Start with the decision you’re trying to make

Different services are useful for different outcomes:

• Leak detection / emergency finding: locate active leaks quickly
• Condition assessment: understand wall loss, cracking, deformation, or coating condition
• Risk ranking: prioritize segments for rehab/replacement
• Regulatory compliance: document asset condition and integrity
• Validation after repairs: confirm the repair was effective

If you don’t define the decision first, it’s easy to buy an inspection that produces data you can’t act on.

2) Match the service to pipe type and constraints

For a distribution network, key factors are:

• Material: cast iron, ductile iron, steel, asbestos cement, PVC/PE
• Diameter
• Pressure vs. gravity
• Age and joint type
• Access points and valves
• Operating continuity requirements
• Flow conditions
• Water quality / product type
• Surface conditions and surrounding environment

Some methods work well in pressurized metallic pipe but poorly in plastic or low-flow systems.

3) Understand the main service categories

Common options include:

Acoustic leak detection

Best for:

• Pressurized water mains
• Suspected active leaks
• Faster screening over large areas

Pros:

• Relatively quick
• Non-destructive
• Good for finding live leaks

Limitations:

• Less useful on plastic pipe
• Performance affected by noise, pressure, and soil conditions
• Doesn’t give detailed structural condition

Inline inspection tools (“smart pigging” / tethered tools)

Best for:

• Metallic pressurized mains with access
• Detailed wall-loss or deformation assessment

Pros:

• High-resolution condition data
• Can identify corrosion, dents, cracks, geometry issues

Limitations:

• Needs suitable pipe geometry and access
• Can be expensive and operationally complex
• Often not practical for many distribution networks, especially small-diameter or highly segmented systems

CCTV / visual inspection

Best for:

• Gravity mains, sewer, vaults, accessible sections, chambers

Pros:

• Direct visual evidence
• Good for identifying defects, infiltration, and obstructions

Limitations:

• Not useful where the pipe cannot be accessed or is not water-clear
• No direct structural thickness measurement

Pressure testing / isolated segment testing

Best for:

• Checking integrity of a known segment
• Verifying repairs or newly installed sections

Pros:

• Simple and widely understood

Limitations:

• Can be disruptive
• Gives limited diagnostic detail
• Not ideal for large networks as a primary assessment tool

Geophysical / remote sensing / advanced analytics

Best for:

• Network-wide screening, prioritization, or corroboration

Pros:

• Can cover large areas
• Useful for identifying hotspots

Limitations:

• Often requires follow-up inspection
• Accuracy varies widely by method and conditions

4) Look at data quality and deliverables

Ask what you will actually receive:

• GIS-ready asset location data
• Defect severity scoring
• Leak coordinates with confidence intervals
• Photos/video
• Wall-loss or anomaly maps
• Recommended action list
• Raw data and processed data ownership
• QA/QC methodology

A good service should not just “find problems”; it should provide usable, auditable outputs that integrate with your asset management system.

5) Evaluate performance on aging networks

For older networks, choose vendors that can demonstrate experience with:

• Mixed materials
• Unknown or incomplete records
• Limited access
• Legacy appurtenances and variable diameters
• Corroded, encrusted, or partially blocked pipes
• Segmented pressure zones

Ask for case studies on assets similar to yours, not generic marketing claims.

6) Compare total cost, not just unit price

Include:

• Mobilization/demobilization
• Traffic control and permitting
• Isolation and shutdown costs
• Customer outage impacts
• Need for excavations or ground-truthing
• Data processing and interpretation
• Follow-up inspection or confirmation work

The cheapest inspection can become the most expensive if it creates lots of ambiguous results.

7) Require validation and references

Before selecting a service, ask for:

• Detection accuracy statistics
• False positive / false negative rates
• Minimum pipe conditions required
• Examples of similar network deployments
• References from utilities with comparable assets
• A pilot project option

A small pilot on representative segments is often the best way to compare services.

8) Consider a layered strategy

For large aging systems, one method usually isn’t enough. A practical approach is:

1. Screen the network to identify high-risk segments
2. Inspect targeted segments in detail
3. Confirm findings with excavation or other ground truth
4. Feed results into the asset risk model
5. Repeat periodically

This is often more effective than trying to inspect everything in the highest-resolution way.

9) Questions to ask each vendor

• What pipe materials, diameters, and operating conditions can you handle?
• What is your minimum detectable defect size?
• How do you handle noise, blockage, or inaccessible sections?
• What are your accuracy and confidence metrics?
• What data formats do you deliver?
• How do you validate findings?
• What portion of the network can be inspected without service interruption?
• What follow-up work is usually required?
• Can you show results from similar utilities?

10) A simple decision rule

• If you need active leak location: start with acoustic/pressure-based leak detection
• If you need structural condition on accessible pressurized metallic mains: consider inline inspection
• If you need visual condition on accessible gravity assets: use CCTV
• If you need broad prioritization: use network screening + targeted verification

If you want, I can help you build a vendor comparison matrix for your specific network by pipe material, diameter, and inspection objective.