You’ve *got issues* with your plumbing drain lines. Things like gurgling drains, slow draining fixtures or full backups. Sometimes these problems can have their roots in an underlying foundation problem. Sometimes it’s just an under-slab plumbing issue with other causes.
Either way, you might want to understand how these issues happen and see if these problems are a good candidate to solve with under-slab tunneling.

At Anchor Foundation Repair, we repair homes all the time that also have drain line issues that need work. We can tell you about drain line problems that are related to foundation settlement as well as drain line trouble that can be handled with tunneling. We provide both foundation repair and tunneling services on many homes in the Brazos Valley area.
This article will describe drain line issues and what they might *look like* in your home. Then we will review two options for reaching and repairing those drain line problems.
3 Drain Line Problems To Address with Under-Slab Tunneling
Drain line issues are something to deal with sooner rather than later. Water leaking under your home through drain lines can end up being a source of foundation settlement or problems. So it’s best to handle drain line leaks as soon as you know you have one.
Here are three kinds of common symptoms you might see in your home that point to potential drain line drama:
- Slow draining tub, sink, or shower that return after a plumber comes out
- Recurring backups with tubs, sinks, or showers
- Gurgling sound coming from fixtures while draining
Your slab foundation and the plumbing underneath are closely related because the systems are intertwined. When one system is failing, it can compromise the other system as well.
Drain Line Symptoms That Could Be Fixed with Tunneling

There are two different types of plumbing lines: lines or pipes that bring clean water into your home and lines or pipes that take used water away from your home. Drain lines take used water from your sinks, tubs and showers, toilets, and washing machines and carry it away.
You want your drain lines working properly, right? If *stuff* doesn’t get carried away to the sewer system, where do you think it goes?
We will only talk about drain line issues in this article. These problems are more commonly tied to possible foundation problems and are good candidates for handling with under-slab tunneling.
1. Slow Draining Problems That Return

The symptoms you might see in your home include a toilet that doesn’t flush strongly, your shower fills up and drains slowly, your dishwasher tries to drain and fills up your sink for a while instead.
The plumber comes out and uses a “roto-rooter” or some other type of drain line cleaning system to clear out the drain lines and make them flow properly and all is well for a while.
Then it happens again, and the plumber comes out again and uses the “roto-rooter”.
Did the problem get solved this time? Not really, because then it keeps happening over and over for some reason.
Under-Slab Causes of Slow Drain Issues
Sometimes drain lines are compromised, broken, or disintegrating underneath your foundation. When the line has a break in it that is letting some water out into the soil beneath your home, trees seek out this water and *fertilizer* source.
Trees can continually intrude upon your drain lines clogging the flow. The tree roots get “roto-rooted” away, all is well for a while, but then they grow back and do it again.
So the invading roots are a problem, but the real problem is that the drain lines are leaking and creating a recurring water source for them. Well, how did that happen?
Foundation Settlement Underlying Cause
When a foundation shifts, breaks, or sags, it can pull the drain lines with it creating a break in the line. The break causes a leak, the leak causes a tree to intrude over and over again and sometimes very quickly into the drain line.

Deteriorating Cast-Iron Drain Lines Underlying Cause
Now, sometimes drain lines are just old and begin to deteriorate all by themselves without the help of a sinking foundation because they are made out of cast iron. Cast-iron drain lines were commonly used in homes built in the early 1970s and before and are now beginning to fail due to rust and degradation.
2. Recurring Backed Up Drain Lines (May Worsen With Rain)
The symptoms you might see in your home are the same as above. A toilet doesn’t flush strongly, your shower fills up and drains slowly, your dishwasher tries to drain and fills up your sink for a while instead.
Another unique symptom you might see is only having a backup problem when it rains. Or even worse, your toilet doesn’t drain away but backs up pushing water onto the floor between your toilet and floor or even into the tub. #notcool
The plumber comes out and tries to use a “roto-rooter” to clear out the drain lines and make them flow properly but it doesn’t work. The “roto-rooter” will only go so far and then it gets stuck or pulls out mud. The presence of mud in the drain lines indicates that the lines are trashed and have been leaking for a while.
Under-Slab Causes of Symptoms that Worsen With Rain

Sometimes drain lines are misaligned or have become completely separated underneath your foundation. In the case of the problem only happening when it rains, rainwater saturates the ground where the separation is and more water cannot drain out of your home because the area is already full of water.
It’s like the ground is a sponge that is full of water and can’t take on any more, so the water doesn’t drain or backs up into your house. So the separated drain lines are a problem and need to be put back together. Well, how did that happen?
Foundation Settlement As Underlying Cause of Symptoms That Worsen With Rain
A shifted or broken foundation can pull the drain lines with it creating a misalignment or complete separation of the line. The misalignment or separation causes your drain lines to drain slowly or back up into the home.
You would definitely want your drain lines put back together and sealed so that used water can flow freely away from your home and all stay inside the pipes where it belongs.
If a problem like this goes on for a long time, you can find yourself with not only a plumbing problem but also a potential developing foundation problem. The tree roots will start coming as well to the water source and causing problems on top of problems.
3. Draining Fixtures That Gurgle

The symptoms you might see in your home are similar to above. Only this time, there is also a gurgling noise when things finally drain away.
Slow, gurgling drains mean that there is a water flow problem and also an airflow or venting problem.
Normally, plumbing drains are vented up through the ceiling of a home with vent pipes that come out through the roof. The air helps the liquid in the drain to flow, it’s a physics thing.
Think of a beverage dispenser with a push button at the bottom to fill your glass, either at a party or on the sidelines of an athletic event. Those dispensers have to have an air outlet at the top to help the liquid flow and the liquid doesn’t flow well when there is no air helping the situation.
When air from somewhere else besides the vent pipe gets into the drain line, like from a break in the line, the drain might gurgle due to the air coming up from below rather than coming down from above. Well, how did that happen?
Erosion, Air Pockets, or Proximity to Venting as Underlying Cause of Gurgling Drains
So you probably have a separated drain line causing the slow draining part. But then the gurgling is caused by air that could be coming from voids or air pockets underneath your foundation.
The leaking water can cause erosion and the soil has moved away creating space that didn’t use to be there. The separation or break could also simply be near the existing plumbing air vents and is taking on excess air during draining.
Ways To Reach Your Plumbing Issues For Repair

Sudden or extremely inconvenient plumbing problems are the #1 reason a plumbing concern moves quickly from a “might do sometime” to a “need to do right away” kind of thing. You want draining water *and stuff* to go where it’s supposed to go and not go where it’s not supposed to go.
Plumbers need to be able to reach the break, misalignment, or separation point in the line to put it back together and repair it right. This can be done in a couple of ways.
Breaking Through the Foundation from Above
Breaking through the foundation from above is messy and intrusive to your home. Jackhammers, dirt, concrete debris and dust, and workers, all inside your home making a pretty big mess. Not that it can’t be done this way, but just know that it might result in some major disruption inside your home, unfortunately.
Tunneling Under the Foundation to Access from Below
All three of the drain line problems described in this article are good candidates for under-slab tunneling. The major advantage to tunneling under the home to access plumbing repair locations is that disruption to your home is minimal and repairs are all done underneath and outside.

The cost of under-slab tunneling can range from $100 to $600 per foot. The longer the tunnel needs to be, the more it costs. Homeowners find tunneling to be worth the cost so that they can stay in their homes during the entire repair process. We’ve got more detailed tunneling cost information too.
Home residents can pretty much live normally while the tunnel is being dug, the repairs are being made, and then the tunnel is filled back in. No dirt or debris piles in your house. No plumbers going in and out, making a mess you have to clean up later. This is a huge benefit for homeowners.
What is the Under-Slab Tunneling Process?
You don’t just start randomly digging a tunnel under your home all willy-nilly. There’s careful planning involved and a basic process to follow.

At Anchor Foundation Repair, we have dug and filled thousands of tunnels in Bryan, College Station, and surrounding Brazos Valley communities like Brenham and Navasota. We’ve got under-slab tunneling down to a science . . . or an art . . . or maybe both.
Whether you consider it an art or science, we’ve got a 5 step process for under-slab tunneling. Check it out in this article next, “How Does Under-Slab Tunneling Work? Basic 5 Step Process.”