Plumbing problems account for 33% of all home inspection defects—making them one of the most common and costly issues inspectors encounter. From hidden leaks that cause thousands in water damage to aging water heaters ready to fail, knowing what to look for separates a thorough inspection from a missed opportunity. This guide covers the essential plumbing inspection checklist every inspector needs, plus the top problems to document in 2026.
Complete Plumbing Inspection Checklist by Area
A systematic room-by-room approach ensures nothing gets missed. Here's what professional inspectors check in each area of the home.
Kitchen Plumbing
- Sink faucet for leaks, drips, and water pressure
- Under-sink pipes, joints, and supply lines
- Drain flow speed and P-trap condition
- Garbage disposal operation and connections
- Dishwasher supply and drain lines
- Refrigerator water line (if applicable)
- Shut-off valves for proper operation
Bathroom Plumbing
- Toilet flush strength, fill time, and base seal
- Tank components for rust and operation
- Sink faucets and aerators for flow issues
- Shower/tub faucets, diverters, and drains
- Caulking around fixtures and tile
- Signs of moisture damage on floors/walls
- Exhaust fan operation and venting
Laundry Room
- Washing machine hoses for cracks/bulges
- Hot and cold shut-off valves
- Drain line and standpipe connections
- Floor drain presence and condition
- Signs of past water damage or leaks
- Utility sink faucet and drain
Water Supply & Main
- Main shut-off valve location and operation
- Water meter reading with fixtures off (leak test)
- Supply pipe material and condition
- Water pressure testing (40-80 PSI ideal)
- Pressure regulator condition if present
- Backflow preventer installation
Outdoor & Exterior
- Hose bibs for leaks and freeze damage
- Sprinkler system heads and connections
- Pool/spa equipment (if applicable)
- Exterior cleanouts location and access
- Drainage grading away from foundation
- Sump pump operation and discharge
Water Heater Inspection Checklist
Water heaters require special attention—they're responsible for significant damage when they fail. A burst water heater costs an average of $4,400 in damage, and units in attics can cause even more extensive harm.
Age & Condition
- Check manufacture date (6-12 year lifespan typical)
- Document serial number and capacity
- Look for rust, corrosion, or scale buildup
- Check for moisture or water stains at base
Safety Components
- T&P relief valve present and not leaking
- Discharge pipe extends 6" from floor
- Drain pan installed (especially upper levels)
- Proper ventilation and draft hood connection
Performance Signs
- Consistent hot water supply
- No unusual noises (popping, gurgling)
- Water temperature reaches setting
- No discoloration or odor in hot water
Gas Units Only
- Blue flame (yellow/red = service needed)
- No scorch marks at base (back drafting)
- Sediment trap on gas line
- Flex gas pipe max 36" with shut-off valve
Top 6 Plumbing Problems Inspectors Find
These are the most frequently documented plumbing defects—knowing what to look for helps you catch issues others might miss.
Active Leaks & Water Damage
Check under sinks, around toilets, and near water heaters for drips, stains, or moisture. Even small leaks cause mold and structural damage over time.
Repair: $150 - $3,000Low Water Pressure
Test multiple fixtures simultaneously. Low pressure indicates clogged pipes, failing pressure regulators, or supply line restrictions.
Repair: $100 - $500Slow or Clogged Drains
Time how long sinks and tubs take to drain. Slow drains signal buildup, improper venting, or main line issues requiring camera inspection.
Repair: $100 - $600Corroded or Outdated Pipes
Galvanized steel, polybutylene, and lead pipes are red flags. Look for green/white corrosion on copper and rust on steel connections.
Repipe: $2,000 - $15,000Toilet Issues
Weak flush, continuous running, rocking base, or moisture around bolts indicate worn components or failed wax seals causing subfloor damage.
Repair: $50 - $400Water Heater Deficiencies
Age over 10 years, rust/corrosion, missing T&P valve, improper venting, or sediment noise all warrant documentation and recommendations.
Replace: $880 - $1,800Pipe Material Reference Guide
Different pipe materials have different lifespans and concerns. Quick identification helps assess overall plumbing system condition.
Expert Plumbing Inspection Tips
The Water Meter Test
Turn off all water fixtures, then check if the meter is still moving. Any movement indicates a hidden leak somewhere in the system—document and recommend further investigation.
Check Insurance Red Flags
Some insurers won't cover homes with polybutylene, galvanized, or lead pipes. Note these materials prominently so buyers can address coverage before closing.
Document Everything
Photograph data plates, pipe materials, visible defects, and water heater conditions. Thorough documentation protects you and provides clients with a valuable reference.
Plumbing Inspection Checklist FAQ
What should a plumbing inspection include?
A comprehensive plumbing inspection covers all fixtures (sinks, toilets, tubs, showers), water supply lines, drain systems, water heater condition, shut-off valves, water pressure testing, and visible pipe materials. Professional inspections may also include sewer camera inspection for an additional fee.
How much does a plumbing inspection cost?
Visual plumbing inspections typically cost $100-$200 as part of a general home inspection. Standalone plumbing inspections range from $150-$500 depending on home size. Sewer camera inspections add $250-$500 but provide valuable insight into drain line condition.
How often should plumbing be inspected?
Professional plumbing inspections are recommended every 1-2 years for preventive maintenance. Water heaters should be inspected every 6-12 months. Homes older than 25 years or with known plumbing issues may benefit from more frequent inspections.
What are signs of hidden plumbing problems?
Warning signs include unexplained increases in water bills, musty odors, water stains on ceilings or walls, slow drains throughout the house, fluctuating water pressure, discolored water, and sounds of running water when fixtures are off.
Should I recommend a sewer camera inspection?
Yes, especially for homes over 20 years old, properties with large trees near sewer lines, or when slow drains suggest main line issues. Camera inspections reveal cracks, root intrusion, and blockages that visual inspection cannot detect.
Conclusion
A thorough plumbing inspection protects buyers from costly surprises and builds your reputation as a detail-oriented professional. By following this checklist—from room-by-room fixture checks to water heater safety assessments—you'll catch the issues that matter most. Remember: plumbing defects found in 33% of inspections represent both a responsibility and an opportunity to deliver exceptional value to your clients.
Inspect Plumbing Systems Like a Pro
HomeInspecto helps you document leaks, pipe conditions, and water heater issues with photo-based reporting that impresses clients and protects your business.
