septic seepage pit

3 Types of Septic Seepage Pits You Really Need to Know About!

If you’re considering a septic tank, you’ll want to know all about seepage pits. You’re also going to need to choose between 3 types of septic seepage pits. That’s exactly what we’re going to show you!

What is a Seepage Pit?

A seepage pit is nothing more than a lined hole in the ground that collects water and allows it to be dispersed and absorbed slowly into the surrounding soil. The hole can be lined with stone, brick, wood, or concrete.

A septic seepage pit disposes of “clean” waste (water that is free of solids or germ-laden material). These pits can be connected to showers, lavatories, bathtubs, clothes washers, and other fixtures that discharge uncontaminated wastewater. They should not be used for toilets, kitchen sinks, or dishwashers.

Seepage pits are called by various names: cesspit, soak pit, latrine pit, dry well, and septic seep pit. But whatever you call it, it’s an important part of a wastewater drainage system for those who are truly off-the-grid or simply have no access to municipal drainage systems.

seepage pit diagram
This diagram shows the general construction of a seepage pit, as well as the inspection pipe, the outflows pipe from the septic tank, and the outlet to other pits if needed.

PRO TIP: Because of concern for the safety of water supplies, seepage pits are prohibited in many areas. So, before you decide on using one, check with your local health or building department. Also, digging the hole is a chore. Keep it shallow if possible, since the sides of a deep pit can collapse and bury the digger.

3 Kinds of Seepage Pits

1. Cylinder of Unmortared Blocks

This type of seepage pit is widely used and relatively easy to construct.

It consists of hollow-core masonry blocks. The core facilitates the passage of water out of the pit. However, solid blocks, or even ordinary bricks, can be used instead, provided that ample space is left between them for the water to seep into the ground.

The cover, made of precast concrete, is best installed professionally since it may weigh up to 500 pounds. The inspection hole in the concrete cover is optional. Most seepage pits never require examination.

seepage pit illustration - cylinder of unmortared blocks
Example of a seepage pit: a cylinder of unmortared blocks

2. Stone-filled Dry Well

A stone-filled dry well is the simplest of all seepage pits. It is a hole completely filled with irregularly sized and shaped rocks.

This is useful for absorbing small amounts of clean water such as the runoff from an outdoor shower or a swimming pool. But its absorption rate is limited. So, for example, it’s not sufficient to accept a large amount of water discharged by a clothes washer.

seepage pit illustration - stone filled dry well
Example of a seepage pit: a stone-filled dry well

3. Drum of Precast Concrete Rings

Pit liners like this one are sold as interlocking rings in diameter of 4 to 8 feet. Tapered openings allow water to flow out of the pit but help keep mud and gravel from seeping in.

The rings, about 3 feet high and 3 to 4 inches thick, weigh over a half-ton. So, it should be installed professionally unless you have the manpower and equipment to assist.

seepage pit illustration - drum of precast concrete rings
Example of a seepage pit: a drum of precast concrete rings

Tips for Seepage Pit Builders

Once you’re certain that regulations in your area permit the use of these pits, you are ready to begin. No matter what type you build, there are some rules of thumb to bear in mind.

  1. A seepage pit should be at least 100 feet from the nearest water well, 20 feet from any building, and 10 feet from the lot line. The space between the house and pit should be unobstructed.
  2. It should be at least 2 feet above ground water and 5 feet above any impermeable bedrock. You can get valuable clues to the nature of the soil in your area by studying the strata of nearby road cuts, stream embankments, and building excavations. Perhaps a more reliable source of information is the soil maps of farm areas published by the U.S. Department of Agriculture.
  3. The best soil for drainage is sandy; it falls into clods that crumble easily. Soil that is dense, hard, dry, dull gray, or mottled is usually nonabsorbent. Inspect the soil condition in your own yard by turning up shovelfulls at several locations. When you find a site that seems suitable, dig a test hole and experiment.
  4. It is best to build on a side of a slope running down from the house. This allows gravity to help with drainage. Do bot build a hollow where rain forms puddles.
  5. The average clothes washer — the appliances most commonly associated with a seepage pit — discharges 44 gallons of water per load. Design the pit for a capacity of 200 gallons to allow for several loads per washday and to guard against overflow during heavy rains and winter freezes. Those are times when absorption is reduced.

Final Thoughts

Building a septic seepage pit is no easy task. It takes research, exploration of your soil, and lots of muscle for the heavy manual labor involved. But if you enjoy the idea of living off the grid in the most natural way possible, a septic seepage pit is the perfect project for your lifestyle.

Call 1-Tom-Plumber

Don’t hesitate to contact us here or call us at 1-Tom-Plumber (1-866-758-6237) if you need help with off-the-grid plumbing projects.

1-Tom-Plumber’s certified team of plumbers and drain technicians respond immediately to any emergency plumbing, drain cleaning, or water damage problem. We also handle the excavation of underground water lines and sewer main lines. Our immediate-response team is available every day and night of the year, even on holidays.

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