Leak Detection in Residences
Leak detection is an important aspect of home inspection. But detection of leaks is really secondary to detection of moisture where it shouldn't be present. The unwanted moisture may be due to a leak, but it could also stem from a different cause such as poor or improper ventilation. And it's possible not only to have moisture where there is no leak but also a (self-contained) leak without accompanying unwanted moisture, such as a worn faucet washer preventing complete valve closure or a failing toilet ball cock. This article discusses how home inspectors approach questions about moisture and leak detection by drawing on plumber secrets and other training.
Leak detection begins with a consideration of the many causes of leaks. Pipe rupture or cracking resulting from corrosion, age, wide temperature swings, or poor installation is the most obvious cause. When this occurs in plumbing fixtures or the traps underneath, detection of the leak is not difficult. When it occurs in the supply line, we can detect the leak indirectly by means of a continuously running meter. But when pipe failure occurs in hidden places such as drainpipe, leak detection (or even awareness) is a much harder problem.
Another big cause of leaks is a problem roof. Because roofs are designed to shed water rather than to form an impervious barrier to it, leaks can develop from age, unusual storm patterns, compromised flashings (especially around penetrations such as skylights and chimneys), or ice dams. Detection of these leaks can be problematic when they go unnoticed for long periods and/or travel along structural members only to appear well removed from the source.
Leak Detection Questions
The home inspection report may indicate a potential leak based on detection of certain evidence. Some evidence is fairly conclusive while other evidence suggests further investigation. If you can hear water running even though all appliances and fixtures are off, or your water bill dramatically increases independent of weather changes, you have probably detected a leak. If your walls or floors are wet, spongy, moist, or discolored or they emit foul odors in the vicinity of drains or sewers, you have detected a moisture problem that may or may not come from a leak. Foundation cracks and/or shifting earth are other signs of water damage that may or may not be leak related.
If the home inspector also conducts a pest inspection, he hunts for potential leaks through detection of more specific evidence of moisture and other conducive conditions for wood-destroying organisms. Detection of stains or mold beneath fixtures, on ceilings below drains, on ceilings below attics, or in attics themselves implies some kind of leak. Detection of standing water beneath fixtures or dripping while water drains suggests a pipe leak.
The home inspector also looks for conducive conditions in the crawl space. Detection of standing water or significant moisture penetration suggests a leak somewhere, perhaps from the storm drain system (or lack thereof). On the other hand, it may indicate a high water table or underground spring.
Detection of a Leak Source
Once leak detection is certain or strongly suspected, attempt to isolate it. Plan for 30-60 minutes of no water usage, including ice makers and water dispensers. Write down the water meter numbers and compare after thirty minutes have elapsed. No difference means the supply plumbing is not leaking. Otherwise, try shutting off bathroom plumbing valves (start with the toilets) and repeat water meter comparisons after 30-minute intervals.
Leak Detection Help
If you feel overwhelmed, schedule a home inspection or other professional for assistance with your leak detection needs.