Case Study: Burst Pipe — Dielectric Union Failure at Galvanized-to-Copper Transition, West Jordan

Event date: Winter 2023 | Property: Pre-1975 ranch, near 3200 West and 7800 South, West Jordan, UT | Event type: Dielectric union failure at galvanized-to-copper transition joint in kitchen wall cavity | Duration: Approximately 14 hours during a workday | Insurance carrier: HO-3 | Approved amount: $5,840 | Deductible: $1,000

What Happened

In the winter of 2023, a West Jordan homeowner returned from work to find a soft spot in the kitchen vinyl flooring in front of the sink and a subtle discoloration at the baseboard along the exterior kitchen wall. The dishwasher appeared dry. The sink connections under the cabinet appeared dry. A slow drip was audible inside the wall — not from the drain, not from the visible supply connections, but from somewhere inside the wall cavity behind the cabinet run. He turned off the water supply at the main and called us.

This property near 3200 West had been partially replumbed during a 1988 kitchen remodel — the original galvanized steel supply plumbing in the kitchen wall had been replaced from the shutoff valves under the sink forward to the fixtures, but the galvanized main in the wall had been retained and connected to the new copper stub-outs via dielectric union fittings. A dielectric union is intended to interrupt electrolytic corrosion between dissimilar metals at a galvanized-to-copper transition — but the union also creates a flow restriction point where calcium carbonate scale from the JVWCD’s 7-to-10-grain-per-gallon supply concentrates, and the union body itself is subject to electrolytic corrosion at the internal metal contact surfaces over time. At 35 years of service on the JVWCD supply, this dielectric union had reached the internal failure threshold. The fracture at the union body had been running for approximately 14 hours by the time the homeowner discovered the event.

What We Found

FLIR thermal imaging of the kitchen exterior wall: cold zone extending 11 linear feet along the wall between 14 and 38 inches above the subfloor — the characteristic horizontal band at framing height produced by a supply line weeping inside the wall cavity. The soft spot in the vinyl flooring corresponded to the cold zone’s lowest thermal point, where water had migrated downward along the wall framing and pooled under the flooring at the cabinet base. Calibrated penetrating moisture meter readings at eight points: wall framing at 23% to 31%, plaster substrate adjacent to the dielectric union location at 27% to 34%, kitchen subfloor OSB at 18% to 24%. Investigation cut at the highest thermal reading: dielectric union fracture confirmed at the galvanized-to-copper transition joint, 20 inches above the subfloor.

This property near the Jordan River corridor — approximately 6 blocks west of the Jordan River Parkway Trail in West Jordan’s pre-1980 lower-elevation corridor — had an ambient basement relative humidity of 61% at the floor level when we took psychrometric readings before deploying equipment. The Jordan River floodplain groundwater table beneath this neighborhood elevates the chronic ambient vapor load in enclosed assemblies throughout the year, particularly in winter when precipitation is highest. The dehumidification for this project had to be sized to address both the acute event wet materials and the Jordan River corridor chronic ambient contribution.

What We Did

A licensed plumber replaced the failed dielectric union and the adjacent galvanized section — extending the copper transition from the existing stub-out back to the galvanized main at the next unaffected fitting — before any drying began. The investigation cut was extended along the full FLIR thermal boundary (11 linear feet) to expose the wet framing and plaster substrate across the complete moisture extent. Antimicrobial treatment of all exposed framing surfaces. Industrial low-grain refrigerant dehumidifier sized to the combined acute event vapor load and Jordan River corridor ambient contribution. Daily penetrating meter readings at all eight points. All eight points confirmed dry standard — framing at 12%–16%, plaster substrate within 4 percentage points of unaffected reference — on day seven. The Jordan River corridor ambient required two additional days of dehumidification beyond what the acute event materials alone would have needed; the ambient stabilized within the ANSI/IICRC S500 target range for two consecutive readings on day seven. HO-3 covered the event. Total approved: $5,840. Deductible: $1,000.

What Made This Project Different From a Standard Supply Line Event

Most supply line events in our service area involve a fitting fracture at a clearly defined location that produces extractable standing water at a floor level. This event produced no standing water. The water was entirely absorbed into the wall assembly — plaster substrate, wood lath, and dimensional framing — across 11 linear feet of kitchen wall. There was nothing to extract. The scope was wall opening, framing assessment, source repair, and structural drying of the opened assembly. The homeowner who calls a plumber first and has the supply line repaired before calling a restoration contractor will lose the moisture scope evidence when the plaster is patched — and will inherit a mold colonization event in the enclosed wall 6 to 8 weeks later. The thermal map is the scope. The thermal map has to be established before the source repair closes the wall.

Frequently Asked Questions

What is a dielectric union and why is it a failure risk?

A dielectric union interrupts electrical continuity between galvanized steel and copper at a transition joint to slow electrolytic corrosion. Over time, two mechanisms degrade it: calcium carbonate scale concentrates at the internal flow restriction, and electrolytic corrosion proceeds within the union body at the metal contact surfaces. At 30 to 40 years on the JVWCD’s hard water supply, these mechanisms typically produce union body failure.

Why does the Jordan River corridor affect dehumidification?

The Jordan River floodplain west of approximately 4000 West in West Jordan sits above a groundwater table elevated by year-round Jordan River base flow and Lake Bonneville smectite clay soil retention. This chronic ambient elevation means dehumidification must address both the acute event vapor load and the Jordan River ambient contribution — otherwise the drying curve stalls when acute event materials approach dry standard and the ambient becomes the dominant load.

Should I call the plumber or restoration company first?

Call the restoration company first, or both simultaneously. If the plumber repairs and patches the wall before we establish the moisture scope with FLIR and penetrating meter readings, the moisture evidence is sealed under new plaster. The insurance scope reflects what was documented before the repair — not what was inferred afterward.

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True Day Water Damage Restoration | 11268 S 2865 W, South Jordan, UT 84095 | (385) 247-9359 | Utah Contractor License: #960332-3505 | IICRC Firm ID: #927354-5258