What can I do if I believe I have a leak, but I cannot find a single drop of water?

This is a question home and business owners ask us every week. Maybe your water bill doubled this month, your boiler keeps losing pressure, or there is a persistent “rotten egg” sewer odor lingering in your basement. When traditional visual inspections fail, tearing up drywall or jackhammering a concrete slab is an expensive and destructive way to guess where the problem lies.

For property owners along the Wasatch Front, shifting soils and extreme freeze-thaw cycles make hidden plumbing failures incredibly common. To pinpoint these invisible issues without destroying your property, leak detection specialists rely on several advanced diagnostic methods. This article showcases two solutions: Plumbing Smoke Testing and Tracer Gas Leak Detection.

Here is how these non-destructive technologies work and which one is right for your home.

What is a Plumbing Smoke Test?

A plumbing smoke test is a diagnostic method used to locate leaks in unpressurized plumbing systems, specifically the Drain, Waste, and Vent (DWV) lines.

If water is leaking out of a drainpipe, or if hazardous sewer gases (like methane and hydrogen sulfide) are seeping into your living space, smoke testing provides an exact visual marker of the failure point.

How Smoke Testing Works

• System Isolation: Technicians temporarily cap off a section of the sewer or vent line so the vapor cannot escape down the main city sewer.
• Vapor Injection: A high-capacity blower pumps a safe, non-toxic, and odorless artificial vapor (smoke) into the plumbing system under slight pressure.
• The Reveal: Because the vapor follows the path of least resistance, it is forced out of any cracks, loose PVC fittings, or broken seals. Wherever the smoke billows out in the house, that is the exact location of the leak.

Common Issues Found with Smoke Testing:

• Dry P-Traps: Evaporated water seals in seldom-used guest bathrooms or basement floor drains.
• Broken Vent Pipes: PVC venting stacks hidden behind drywall that have cracked due to house settling.
• Failed Toilet Seals: Degraded wax rings allowing sewer gas to escape from the base of the toilet.
• Rodent Intrusions: Identifying entry points where rodents have chewed through drainage lines.

What is Tracer Gas Leak Detection?

You cannot pump lightweight smoke into a high-pressure water supply line to find a leak. For hidden leaks in lines carrying potable water, professionals use tracer gas.

Tracer gas leak detection is a non-invasive method used to find microscopic pinhole leaks in pressurized water supply lines, underground mains, and hydronic heating systems.

How Tracer Gas Testing Works

• System Draining: The leaking water supply line is shut off and drained of existing water.
• Gas Pressurization: A safe blend of non-toxic rising gases is pumped into the empty water line to pressurize the system.
• Sensor Detection: The small particles of the gases easily escape through microscopic pinhole leaks in the pipe and rises straight up through dirt, gravel, concrete slabs, and flooring.
• The Reveal: Technicians run highly sensitive “sniffer” devices over the floor or ground. The sensor detects the exact concentration peak of the escaping gas, pinpointing the leak’s location with extreme accuracy.

Common Issues Found with Tracer Gas:

• Under-Slab Leaks: Hot or cold water lines that have corroded beneath concrete basement floors due to hard water scale and soil friction.
• Underground Water Mains: Main lines running from the city meter to the house that are losing water into the surrounding soil.
• Radiant Floor Heating: Hydronic boiler systems losing pressure beneath finished flooring where acoustic listening devices cannot hear the leak.

Smoke vs. Tracer Gas: Which Do You Need?

To help determine which diagnostic tool your property requires, use this quick-reference guide based on the symptoms you are experiencing: