Water Pipes Under Slab: What You Need to Know

Water pipes under slab can be a mystery to many homeowners. The pipes are typically made of copper, PEX, or PVC, and are designed to withstand the weight of the slab and surrounding soil.

These pipes are usually 1-2 inches in diameter and are laid out in a grid pattern under the slab. The pipes are connected to each other using fittings such as couplings and elbows.

The pipes are usually buried 6-12 inches deep under the slab, but can be as deep as 18 inches in some cases. This depth helps to protect the pipes from freezing temperatures and physical damage.

The pipes are often covered with a layer of insulation to prevent heat loss and protect the pipes from damage.

Water pipes under slab are typically made of durable materials such as PVC, PEX, or copper, which can withstand the weight and pressure of the slab and surrounding soil.

These pipes are usually installed in a way that allows for easy access and maintenance, with connections to water meters, shutoff valves, and other essential components.

Water pipes under slab can be prone to leaks and damage from soil settlement, freezing temperatures, and corrosive substances.

Leaks in water pipes under slab can go undetected for a long time, causing significant water damage and mold growth before they're discovered.

In some cases, water pipes under slab may be exposed to high water pressure, which can lead to pipe bursts and costly repairs.

Regular inspections and maintenance can help identify potential issues with water pipes under slab before they become major problems.

Aging pipes can lead to small pinhole leaks, especially if they're near or at the end of their useful lives. This is a common problem, and it's essential to address it before it causes significant damage.

High water pressure, above 80psi, can also cause damage to your plumbing pipes, resulting in under slab leaks. I've seen this happen in homes with older plumbing systems.

Aging pipes are not the only issue, corrosion is another significant factor. Acidic water can cause the premature corrosion of metal plumbing pipes, including copper. This can lead to leaks and other problems.

Here are some common causes of problems with water pipes under slab:

Soil Expansion/Contraction is a major culprit in slab leaks. It's caused by the ground conditions changing from dry to wet, which makes the soil swell and shrink.

This type of soil shift is common in Texas, where the soil composition is largely cracking clay, sandy soil, and other types prone to vertical or lateral shifting. As the soil moves, it can damage water pipes.

The movement of the soil under the foundation can potentially damage water pipes. It's a chain reaction that may go unnoticed for some time, but can cause significant damage to your home.

Here are some key facts about soil expansion/contraction:

Improper construction or materials used during the building process can lead to slab leaks. Damaged pipes, such as those that are bent, dented, or kinked, are prone to bursting under varying water pressure and the abrasive property of the surrounding ground.

Cast iron and galvanized pipes, commonly found in older homes, are also a contributing factor to slab leaks. They are prone to rust and clogging as they age, making them more susceptible to leaks.

The choice of plumbing materials can make a big difference. Newer homes often use plastic pipes like PVC, CPVC, or PEX, which are corrosion resistant and easy to work with.

Abrasion and Outside Pressures can cause slab leaks over time. Friction from rubbing against nearby pipes, concrete, soil, and other materials can weaken pipes and lead to leaks.

Growing tree roots can also cause damage to pipes, especially if they're made of materials like PVC or CPVC. These roots can wrap around pipes, restricting water flow and causing pressure to build up.

Earthquakes can put immense pressure on pipes, causing them to crack and leak. It's not just the initial quake that can cause damage, but also the aftershocks that can continue to stress pipes.

Soil erosion can also lead to slab leaks. As the soil around your home shifts and settles, it can put pressure on your pipes, causing them to crack and leak.

A table showing the common causes of slab leaks due to abrasion and outside pressures:

A slab leak can be a nightmare to deal with, but knowing the warning signs can help you catch it early. Sudden spikes in your water bill are a common sign of a slab leak.

You may also hear the sound of running water when all taps and faucets are turned off, or notice moisture or mildew under carpeting. Another clue is a moving water meter dial when pipes aren't in use.

Here are some common signs of a slab leak:

If you notice one or more of these signs, don't hesitate to call a professional for help.

If you notice water damage or discoloration on your ceiling, it could be a sign that your plumbing pipes under the slab are leaking. This is often caused by the weight of the home crushing the pipes.

Look for cracks in the concrete slab, as these can be a sign that the pipes beneath are damaged. The slab foundation is designed to protect the pipes from physical damage, but if it's compromised, the pipes can be at risk.

Foul smells and strange odors coming from the sewer or water lines could indicate a problem with the pipes under the slab. This is because the slab foundation helps to keep foul smells from entering the home.

If you notice that your water bills are higher than usual, it could be a sign that there's a leak in the pipes under the slab. Gravity flow pushes all waste to the street sewer system, so if there's a leak, it can cause an increase in water consumption.

A sudden drop in water pressure could also be a sign of a problem with the pipes under the slab. This is because the pipes are installed at a gradual angle, and if there's a blockage or leak, it can disrupt the flow of water.

If you suspect a slab leak in your home, there are several warning signs to look out for. A sudden spike in your water bill is a common indicator, as a slab leak can cause a significant increase in water usage.

A sound of running water under your floors, even when all faucets are tightly shut, is another clear sign of a slab leak. This is because the leak is causing water to flow continuously, even when no water is being used.

Water spots on your floor are another physical sign of a slab leak. These spots can appear as small stains or discolorations on the surface of your flooring.

You may also notice gaps between your flooring and wall, or it may be hard to open doors or windows due to the pressure from the leak.

A slab leak can also cause your flooring to become soft, warped, or uneven, leading to a range of problems.

Here are some common signs of a slab leak:

If you notice any of these signs, it's essential to call a professional plumber or pipe lining technician immediately to have the leak detected and repaired.