Common Plumbing Problems for Building Inspectors

Plumbing problems are among the most frequently discovered defects during a building inspection. Whether visible leaks, inadequate drainage, or non-compliant installations, your ability to identify these problems quickly and accurately defines the quality of your professional service.

An effective plumbing inspection goes beyond simple leak detection. It reveals the general condition of systems, anticipates future failures, and protects your clients against costly repairs. Mastering common defects allows you to provide comprehensive reports and strengthen your credibility.

Common Failures in Supply Systems

The water supply system transports potable water under pressure to all points of use in the building. Problems in this system can cause significant damage and affect water quality.

Leaks at connections are probably the most common problem. Carefully check all visible joints, particularly under sinks, at toilets, and near the water heater. Water traces, corrosion, or white mineral deposits often indicate a slow leak that has persisted for a long time.

Abnormal Water Pressure

Excessive water pressure can damage appliances and cause premature leaks. Conversely, too low pressure suggests obstructed piping, partially closed valves, or municipal system failure. Use a pressure gauge to measure static pressure, which should be between 40 and 80 PSI.

Lead or polybutylene plumbing pipes constitute major problems requiring immediate attention in your report. Lead poses health risks, while polybutylene (gray or blue pipes) is prone to premature failures.

Corrosion and Deterioration

Examine the condition of visible pipes in the basement, crawl space, and near the water heater. Corrosion appears as greenish stains on copper, rust on galvanized steel, or discoloration on plastic pipes. Heavily corroded pipes must be reported as requiring short-term replacement.

Connections between different metals create galvanic corrosion. A copper pipe directly connected to a galvanized steel pipe without an appropriate dielectric connector will deteriorate rapidly at the junction.

Common Problems in Drainage Systems

The drainage and venting system evacuates wastewater by gravity and provides necessary ventilation for proper operation. Defects in this system cause odors, backups, and may indicate more serious structural problems.

Slow drains are the most obvious symptom of a drainage problem. If multiple fixtures drain slowly, this suggests a blockage in the main line rather than local obstructions. Test each drain and note the drainage speed.

Inadequate Ventilation

A deficient ventilation system creates gurgling noises in drains, sewer odors, and can siphon water from traps. Verify that each group of fixtures has access to appropriate ventilation. Vents must extend above the roof, never terminate in the attic.

Inadequate slopes of drainage pipes prevent normal flow. The recommended slope is 1/4 inch per foot. Pipe sections that present reverse slopes or flat sections will accumulate debris and eventually clog.

Leaks and Damage

Carefully inspect under sinks and around toilets to detect wastewater leaks. These leaks are particularly problematic because they can cause hidden water damage and mold problems before being detected.

Aging cast iron drainage pipes deteriorate from the inside. Gently tap exposed pipes with a screwdriver: a hollow or dull sound indicates advanced corrosion. ABS or PVC pipes may present cracks, particularly at connections.

Fixtures and Equipment to Monitor

Each plumbing fixture presents its own potential failure points. Your inspection must be systematic to miss nothing.

Water Heater

The water heater requires special attention as its failure can cause significant damage. Check the age of the appliance (the nameplate indicates the manufacturing date), look for signs of rust or corrosion, and test the pressure relief valve.

Water traces at the top of the tank or at the base indicate leaks. Calcium buildup on connections suggests slow leaks. The pressure relief valve must have a discharge pipe terminating near the floor and never directly connected to the drain.

Toilets and Faucets

Toilets that rock on their base indicate a failed wax ring or damaged floor. Check stability by gently pushing on the bowl. Base leaks leave water traces or stains on the floor.

Operate all faucets to check operation. Dripping faucets, controls difficult to turn, or leaks at connections must be documented. Modern single-lever faucets should require no effort to operate.

How to Test Without Exceeding Visual Inspection Scope

Your inspector mandate is limited to a visual and non-invasive inspection. You must not disassemble components, open walls, or perform destructive tests.

To test drains, simply run water for 30 to 60 seconds and observe the flow. Listen for abnormal noises. Check under the sink while water is running to detect active leaks. This is a perfectly acceptable non-invasive test.

Flush toilets and observe tank refilling. The mechanism should stop running completely once the level is reached. A weak flush or very slow refilling indicates potential problems.

Limits of Your Inspection

You cannot and must not inspect plumbing sections hidden in walls or under slabs. If you suspect problems based on visual clues (moisture stains, odors, noises), recommend a specialized inspection by a licensed plumber.

Similarly, do not attempt to assess the internal condition of sewer pipes or septic tank. These systems require specialized equipment. Your role is to identify visible symptoms and recommend further investigations when necessary.

Clearly Document Observed Problems

Photographic documentation is essential for plumbing defects. A photo of an active leak, corroded pipe, or clogged drain is worth a thousand words in your report.

For each identified problem, specify the exact location, nature of the defect, and your recommendation. Avoid vague terms like 'have plumbing checked.' Be specific: 'active leak detected at supply pipe connection under kitchen sink – repair required.'

Defect Classification

Classify your observations according to their urgency. An active leak requires immediate repair. Aging but functional pipes can be reported for future planning. This prioritization helps your clients prioritize repairs.

Plumbing problems often evolve rapidly. A small leak today can cause major damage tomorrow. Your thorough inspection and precise documentation protect your clients' safety and investment while establishing your professionalism.