How Plumbing Leaks Destroy Foundations
I always thought of plumbing leaks as something that floods your house. Water spraying everywhere, obvious damage, immediate emergency. Underground leaks are way more insidious.
The Slow Erosion
Tom's leak was tiny. Maybe a gallon an hour. Not enough to be dramatic, but running 24/7 for two years? That's over 17,000 gallons of water slowly washing through the soil under his foundation.
Water moving through soil takes soil particles with it. Not a lot at once, but constantly. Day after day, month after month, tiny particles washing away. Eventually you've got channels and voids where there used to be solid support.
The Localized Settlement
What made Tom's situation clear to diagnose was that the settlement was localized. One corner dropping. The rest of the house stable. That pattern screams "something is happening at that corner."
Rain affects the whole foundation more or less equally. General settlement happens more or less everywhere. But a plumbing leak? That's a point source. The damage radiates from where the leak is.
The Hidden Nature
Tom had no idea anything was wrong. The leak was underground. No water in the basement. No wet spots in the yard that he noticed. The soil just quietly absorbed it all while washing away from underneath.
By the time symptoms showed up as cracks and sticking doors, the damage was already done. The foundation had already settled. The soil had already eroded.
How Tom Could Have Caught It Earlier
Looking back, there were signs. Tom just didn't know to look for them.
The Water Bill
The bill went up $47 a month and stayed up. That's not seasonal variation. That's not longer showers. That's a consistent change in usage that should have prompted investigation.
I've learned from Tom. Now I actually look at my water bills month to month. Any unexplained increase that persists for more than one billing cycle, I investigate.
The Meter Test
Tom could have done this himself in 5 minutes. Turn off all water in the house. Every faucet, every toilet, every appliance. Then go look at the water meter. If it's still spinning, water is going somewhere you don't know about.
Tom's meter would have been spinning. He just never checked.
The Green Grass Clue
Tom's wife mentioned later that the grass near that corner was always greener than the rest of the yard. She thought it was because that spot got more sun. It was actually being watered constantly by the leak.
Unusual plant growth near a foundation can indicate water presence. Could be a leak. Could be poor drainage. Either way, worth investigating.
The Soft Spot
After the fact, Tom noticed that the ground near the leak had always been softer than elsewhere. You'd sink in a little more walking over that area. The soil was constantly saturated and not as compacted.
He'd walked over that spot a hundred times mowing the lawn. Never thought about why it felt different.
Types of Plumbing Leaks That Cause Damage
Tom's was a supply line leak, but I've learned there are several types that can mess up foundations.
Supply Line Leaks
Water supply pipes are under pressure. When they leak, water flows constantly. Even a tiny crack produces substantial water over time. Tom's was in the copper line to his hose bib. A joint had failed underground where he couldn't see it.
Supply leaks are pure water, which is somewhat better than sewer leaks. But they're under pressure, so they can move more water.
Sewer Line Leaks
My neighbor across the street had a different problem. His sewer line had cracked from tree root intrusion. Waste water was seeping into the soil around his foundation.
Sewer leaks are lower volume than supply leaks since there's no pressure. But they're nastier. The waste introduces chemicals and organic matter into the soil. Roots grow toward the nutrient source. The leak gets worse over time.
His repair was $4,500 for the sewer line plus some foundation crack injection.
Sprinkler System Leaks
Helen, my other neighbor, had a sprinkler head near her foundation that was leaking at the connection. Every time the sprinklers ran, water was pumping directly into the soil against her foundation wall.
She caught it early, fortunately. Just some efflorescence on the basement wall to show water was getting through. Fixed the sprinkler head for $15 and no foundation damage.
Foundation Penetration Leaks
Where pipes go through the foundation wall, there's supposed to be a seal. Rick's seen plenty of houses where that seal has failed and water runs along the pipe and into the basement during rain. Not technically a plumbing leak, but related.
Tom's Repair Process
Fixing the damage was more complicated than fixing the leak.
Fixing the Leak First
Step one was stopping the water. The plumber dug up the supply line, found the failed joint, and replaced a 4-foot section of pipe. Total: $800 including the digging and reburying.
Until the leak was fixed, there was no point doing foundation work. The soil would just keep eroding.
Assessing the Soil Damage
The foundation contractor probed around the foundation with a metal rod. He found soft, saturated soil in a cone-shaped area radiating from where the leak had been. Some voids where soil had washed away entirely.
The good news: the damage was localized. The rest of the foundation was on solid ground.
The Foundation Repair
Tom ended up with three push piers under the settled corner. They drove steel piers down through the bad soil until they hit something solid, about 15 feet down. Then they attached brackets to the foundation and transferred the load to the piers.
They also did some void filling with polyurethane foam to stabilize the soil in the affected area.
Total foundation work: $11,000. Tom tried not to think about how much cheaper it would have been if he'd noticed the water bill thing two years earlier.
What I Do Differently Now
Tom's experience made me paranoid about hidden leaks. Here's what I've added to my routine.
Water Bill Tracking
I actually look at my water bills now. Not just pay them. I track usage month to month in a spreadsheet. Any jump I can't explain, I investigate. Takes 30 seconds per month.
The Annual Meter Test
Once a year, usually in spring, I do Tom's test. Turn off all the water in the house. Check the meter. Wait 15 minutes. Check again. If it moved, I've got a leak somewhere. So far, nothing. But I check.
Visual Inspection of Lines
I know roughly where my water and sewer lines run. When I'm out in the yard, I pay attention to that area. Looking for soft spots, unusual plant growth, wet areas when it hasn't rained. Just being aware.
Outdoor Faucet Check
Tom's leak was at an outdoor faucet. I now check my outdoor faucets every spring when I reconnect them after winter. Turn them on, watch the ground around where they penetrate the foundation. Any seepage means something's wrong.