Case Study: Sewage Backup — North American Monsoon Surcharge, South Jordan

Event date: August 2023 | Property: 1990s-era two-story with finished basement, near 1300 West, South Jordan | Event type: Category 3 sewage backup from North American Monsoon sewer main hydraulic surcharge | Duration: Active backflow for approximately 40 minutes during the storm event; standing water contact approximately 3 hours before homeowner discovered event | Insurance carrier: Bear River Mutual HO-3 with sewer backup endorsement | Approved amount: $14,200 | Deductible: $1,000

What Happened

In August 2023, a North American Monsoon convective storm delivered approximately 1.4 inches of precipitation to southwest Salt Lake County in under 90 minutes — a rainfall intensity sufficient to overwhelm the hydraulic capacity of South Jordan’s municipal sewer collection mains in the lower-elevation western corridor near 1300 West. When the sewer main pressure exceeded the elevation of the lowest connected below-grade fixtures in homes along this corridor, sewage backflowed through those fixtures and into the finished living spaces below.

The dual-fixture simultaneous backflow pattern — the basement floor drain and the basement bathroom toilet backflowing at the same moment — confirmed sewer main hydraulic surcharge rather than a localized lateral blockage. A localized blockage would have affected one fixture, not both simultaneously. The homeowner had been watching the storm from her second-floor window, had not been in the basement, and discovered the event approximately three hours after it began when she went downstairs to check. Approximately 4 inches of Category 3 sewage-contaminated water covered 220 square feet of the finished basement family room floor. Hydrogen sulfide was detectable from the staircase landing before entry.

What We Did

Before any personnel entered the affected space: hydrogen sulfide assessment with a calibrated monitor at the staircase landing. The H₂S reading was 8 parts per million — below the OSHA permissible ceiling of 20 ppm but sufficient to require respiratory protection given the duration of potential exposure during the work scope. Full PPE deployed at the containment boundary: powered air-purifying respirators with P100 and organic vapor cartridges, double-gloved nitrile, sealed Tyvek coveralls. HEPA air scrubbers established in negative air pressure mode at the staircase entry before any equipment entered the affected space. Containment barrier at the staircase landing to prevent cross-contamination of the unaffected upper levels.

Carpet, pad, and the lower 10 inches of drywall on three perimeter walls were removed within the containment zone and double-bagged for regulated waste disposal. Three passes of EPA-registered broad-spectrum disinfectant at required concentration and minimum 15-minute dwell time were applied to the concrete floor and all exposed framing and masonry surfaces. Structural drying equipment ran for six days. All 22 monitoring points confirmed dry standard on day six.

During the post-extraction FLIR thermal imaging scan conducted as drying equipment was being placed, we identified a separate pre-existing cold zone on the northeast basement wall — chronic Lake Bonneville clay cold joint seepage moisture at 19% to 23% framing moisture at four additional points, unrelated to the sewage event and present before the event. This was documented separately for the homeowner with specific readings and a professional recommendation for interior drain tile assessment before the following spring. It was not included in the Bear River Mutual claim scope.

Insurance Outcome

Bear River Mutual HO-3 with a sewer backup endorsement covered the event. Total approved: $14,200. Deductible: $1,000. The sewer backup endorsement is a specific add-on rider that many homeowners do not know they need until an event makes them realize their base HO-3 policy does not cover sewage backup. The base HO-3 policy covers sudden and accidental water damage from internal supply line failures. It does not typically cover sewage backup or overflow from a drain, sewer, or septic system without the endorsement. If this homeowner had not had the sewer backup endorsement, the $14,200 project would have been entirely out-of-pocket.

The Retired Teacher

She had lived in the house for 22 years. She had raised three children in that basement family room, held a book club there every other Wednesday for a decade, and refinished the flooring herself in 2015 after the last child left for college. She stood in the driveway while we worked and mentioned none of this to us — but she told us at the project close walkthrough two weeks later, standing in the rebuilt basement with new luxury vinyl plank flooring in a pattern she had always preferred but never gotten around to choosing. She said it looked better than it did before the backup. We told her the pre-existing seepage on the northeast wall was going to require attention before the next spring. She scheduled the waterproofing contractor the following week. That was the right outcome.

Frequently Asked Questions

Does standard homeowners insurance cover sewage backup?

A standard HO-3 policy typically does not cover sewage backup without a specific endorsement — sometimes called a sewer backup rider or a water backup and sump overflow endorsement. This endorsement is usually inexpensive relative to the coverage it provides. A sewage backup event without the endorsement is typically entirely out-of-pocket. If you are not sure whether your policy includes it, check your declarations page now — not after an event.

What is the dual-fixture simultaneous backflow pattern?

When sewer main hydraulic surcharge occurs, the main pressure rises above the elevation of the lowest connected fixtures. Both the basement floor drain and the basement toilet backflow simultaneously. This simultaneous dual-fixture pattern distinguishes sewer main surcharge from a localized lateral blockage — a localized blockage affects one fixture or one section of the lateral, not all below-grade fixtures at the same moment.

Is it safe to stay in the home during sewage cleanup?

If the affected area is isolated to a basement with containment established and HEPA air scrubbers in negative air pressure mode, the upper levels may be occupiable. For larger Category 3 events or events where the affected area cannot be effectively contained, temporary relocation is advisable. We assess specific conditions on arrival and provide a specific recommendation.

What causes North American Monsoon sewer surcharge in South Jordan?

The North American Monsoon pattern from July through September delivers Gulf of California moisture flow to the Salt Lake Valley in the form of intense convective precipitation — 1 to 2 inches in under 90 minutes during significant events. This precipitation volume enters the storm water and sanitary sewer systems faster than the collection mains can convey it, causing hydraulic surcharge that reverses flow through the lowest connected fixtures in affected homes. Properties in the lower-elevation corridors of South Jordan, west of Bangerter Highway, are at higher risk during significant events.

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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