Septic Tank Distribution Box Problems: Causes and Solutions

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Septic tank distribution boxes play a crucial role in the wastewater management system. They are responsible for distributing the treated effluent from the septic tank to the drain field or leach field. However, septic tank distribution boxes are susceptible to various problems, which can cause system failures and result in costly repairs. In this article, we will discuss some common septic tank distribution box problems and their causes, along with some solutions.

Signs Of A Septic Tank Distribution Box Problems

  • Foul odors emanating from the septic system.
  • Puddles of wastewater on the ground near the distribution box.
  • Lush vegetation growing over the distribution box.
  • Slow-draining sinks, showers, and toilets.

Septic Tank Distribution Box Problems: Causes

Some of the most common causes of septic tank distribution box problems are:

1. Leaks caused by freezing and corrosion

A poorly insulated septic tank is susceptible to freezing during the winter months. When the temperature drops, the water in the septic tank can freeze and expand, causing cracks in the pipes, concrete walls and floors of the distribution box. As a result, wastewater can leak out of the box and contaminate the surrounding soil.

In addition to freezing, corrosion is another common cause of leaks in the septic distribution box. Hydrogen sulfide gas, produced during the anaerobic digestion of waste in the septic tank, reacts with low levels of oxygen in the septic tank to form sulfuric acid (H2SO4). Over time, this acid can corrode the concrete walls and floors of the distribution box, resulting in leaks.

Solutions to septic distribution box leaks

  • Insulate the septic tank to prevent freezing.
  • Installing a septic tank air vent can also prevent septic distribution box leaks. It ensures proper ventilation, reducing the buildup of hydrogen sulfide gas. Keep the vent free of debris and clogs for optimal performance.
  • Install an aerobic treatment unit to reduce the production of hydrogen sulfide gas.
  • Repair or replace the distribution box if it is corroded or damaged.
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2. Clogs caused by unbiodegradable waste

Another common septic distribution box problem is clogging, which is caused by the accumulation of unbiodegradable waste in the system. Items such as flushable wipes, feminine pads, tampon and cotton swabs can clog the distribution box and cause backups in the septic system. Additionally, clogged filters can prevent the treated effluent from flowing into the drain field, resulting in system failures.

Solutions to septic distribution box clogs

  • Avoid flushing non-biodegradable items down the toilet
  • Regularly pump the septic tank to remove accumulated waste
  • Install a lint filter to trap lint and other small particles before they reach the distribution box
  • Install a distribution box with larger compartments to prevent clogging

3. Trees Roots Intrusion

Root intrusion is a common problem that can occur in septic tank distribution boxes. Roots from nearby trees and shrubs can grow into the distribution box through small cracks or openings, causing blockages or other damage. Once roots have penetrated the distribution box, they can continue to grow and expand, eventually causing more severe damage to the septic system.

Root intrusion is more likely to occur when trees and shrubs are planted too close to the septic system. As the roots grow, they can wrap around the pipes and distribution box, causing them to crack or become dislodged. In addition to causing blockages, root intrusion can also lead to leaks, which can contaminate the surrounding soil and water sources.

One solution to prevent root intrusion in septic tank distribution boxes is to plant shallow-rooted plants around the septic system. Shallow-rooted plants have roots that grow close to the surface and are less likely to penetrate the distribution box or septic pipes. Examples of shallow-rooted plants include annual flowers, grasses, and groundcovers. These plants also add aesthetic value to the landscape.

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4. Poorly Installed Septic Distribution Box

Another common problem is a poorly installed septic distribution box. The box should be level to ensure even effluent distribution and mustn’t be tilted or slanted. If the distribution box is tilted, effluent can flow unevenly, causing some areas of the drain field to become oversaturated while others remain dry. This uneven distribution of effluent can cause the system to fail prematurely.

5. Not Regulating Septic Distribution Box Outlet Holes

Another common problem is not regulating the septic distribution box outlet holes to control effluent flow in accordance with the amount of organic waste your household produces. This can cause too much effluent to enter the drain field, which can overwhelm the soil’s ability to absorb the liquid. When the soil becomes oversaturated, wastewater can back up into the house or the yard, leading to a smelly mess.

6. Age

Like any other component of a septic system, the distribution box can wear out over time. If it is old and has not been properly maintained, it can develop cracks, leaks, and other problems.

Septic Tank Distribution Box Problems: FAQs

Here are some frequently asked questions about septic tank distribution box problems:

The distribution box (D box) in a septic system should be installed at a minimum distance of 5 feet from the septic tank. It should also be placed at least 8 feet away from the drain field to ensure proper wastewater distribution. Proper placement of the D box is important for the optimal functioning of the entire septic system.

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Septic tank distribution boxes can be made from either plastic or concrete. However, concrete distribution boxes are much sturdier and more durable than their plastic counterparts. Concrete boxes can withstand the weight of soil and heavy machinery, as well as the corrosive effects of wastewater over time. While plastic boxes may be more affordable, they may not last as long or provide the same level of protection as concrete distribution boxes.

The cost of replacing a septic tank distribution box can vary depending on several factors, such as the size of the box, the type of material used, and the extent of the damage. On average, homeowners can expect to pay anywhere from $1000 to $3000 for a new distribution box, including the cost of labor and materials. It is important to hire a licensed and experienced professional for the replacement to ensure that the new distribution box is properly installed and functioning effectively. Regular maintenance and inspections can help prevent the need for costly repairs or replacements in the future.

If your septic distribution box is full of water, it is a sign that your drain field is likely full and unable to receive any more effluent. This can cause backups and other issues in your septic system. In order to resolve the problem, you will need to have your septic tank pumped out.


Septic tank distribution box problems can cause serious issues in the septic system. Freezing and corrosion can result in leaks, while clogs can cause backups and system failures. It is essential to recognize the signs of these problems and take action to prevent them. Regular maintenance, proper waste disposal, and professional inspections can help ensure the smooth operation of your septic system.