What Is a Leach Field and How Does It Work?

What Is a Leach Field and How Does It Work?

What is a Leach Field?

Septic drain fields, also known as leach fields or leach drains, are underground wastewater disposal facilities used to remove pollutants and impurities from the liquid that emerges from a septic tank following anaerobic digestion.

A microbial ecosystem catabolizes organic molecules in the liquid. A septic system is made up of a septic drain field, a septic tank, and related pipe.

The drain field is often made up of trenches with perforated pipes and porous material (commonly gravel) topped by a layer of soil to keep animals (and surface runoff) from reaching the wastewater spread inside those trenches.

The primary design issues are both hydraulic for the volume of wastewater that must be disposed of and catabolic for the wastewater’s long-term biological oxygen requirement. A septic reserve area is the land area set aside for the septic drain field (SRA).

Sewage farms, too, dispose of wastewater through a network of ditches and lagoons (often with little or no pre-treatment).

These are more common in dry areas because the surface waterflow enables for irrigation (and fertilization) of agricultural land.

Leach Field Location

Leach fields are usually found in a broad, flat, open part of your yard. They can have many ditches ranging in depth from 18 to 36 inches, width ranging from one to three feet, and length ranging from one to 100 feet.

Each trench is normally six feet apart. Leach fields can endure up to 25 years if properly maintained.

How a Leach Field Works

Your septic system is made up of a septic tank, pipes, and a drain field. This implies that in order to understand how a leach field works, you must first comprehend the entire septic system.

The following is how your septic system and leach field work:

  1. All water drains from your home through a single main drainage line into a septic tank.
  2. A septic tank is a watertight container that is underground and is often composed of concrete, fiberglass, or polyethylene. Its duty is to retain the wastewater long enough for particles to settle to the bottom and form sludge, while oil and grease float to the surface and produce scum. Compartments and a T-shaped outlet keep sludge and scum from exiting the tank and entering the drainfield.
  3. The liquid wastewater (effluent) is then discharged from the tank onto the drainfield.
  4. A drain field is a shallow, covered excavation excavated in unsaturated soil. Pretreated wastewater is released via pipelines onto porous surfaces, allowing the wastewater to filter through the soil. As it percolates through the soil, wastewater is accepted, treated, and dispersed, eventually discharging to groundwater. If the drainfield becomes overburdened with liquid, it might flood, allowing sewage to spill to the ground surface or cause backups in toilets and sinks.
  5. Finally, the wastewater percolates into the soil, eliminating dangerous coliform bacteria, viruses, and nutrients naturally. Coliform bacteria are bacteria that live mostly in the intestines of humans and other warm-blooded animals. It’s a sign of human fecal contamination.

How to Tell if Your Leach Field is Failing

A well-maintained leach field is both unseen and silent. There are, however, a few crucial symptoms that your leach field is failing:

  • When switched on, the pipes gurgle.
  • Drains that are slow to drain or plumbing backups
  • Problems with toilet flushing (low pressure, slow flushing, not flushing).
  • Sewage scents emanating from sewers, septic tanks, or leach fields.
  • Over the leach field, there may be standing water or wet, mushy grass.

Do you have a septic system?

You may already be aware that you have a septic system. If you don’t know, here are several tell-tale indicators that you most likely do:

  • Your next-door neighbors have a septic system.
  • You drink from a well.
  • There is no meter on the waterline that enters your home.
  • Your water bill or property tax bill shows a “$0.00 Sewer Amount Charged.”
  • Where can you discover your septic system?
  • Once you’ve confirmed that you have a septic system, you may locate it by doing the following:
  • Contact a septic system provider to assist you in locating it.
  • Look around your yard for lids and manhole covers.
  • Examine your house’s “as built” drawing.

Is it possible to fix a septic drain field?

In a septic drain field, it doesn’t take long to fix a clog. However, there are some things that could go wrong with a leach field, like bacterial mat growth. Preventing costly leach field replacement services is the best way to keep costs down.

Follow these plumbing tips at home to keep your leach field from failing:

Commit to having your septic system checked and diagnosed every year.

Schedule septic tank pumping every three to five years. To find out how often you should be pumping your septic tank, look at the chart on the septic tank pumping page.

Divert water that comes from a lot of rain or snow away from the leach field.

The leach field should not be used to park cars, build structures, or put heavy things on top of.

To use less water, only do one load of laundry a day.

When possible, use garbage disposals only a few times a week or so (or not at all).

If you want to flush something other than toilet paper and body fluids, you should not.

Drain grease, chemicals (like bleach and ammonia), or paint down the sink, not down the drain.

Typical Leach Field Problems

It is usually the leach field that is the source of most problems with a septic tank.

The soil in the leach field will become clogged if there is a lot of solid waste or water. This will make it hard for the water to flow freely.

These problems usually happen when:

  • You drain chemicals, paint, grease, and other things that are hard to filter.
  • You try to process more wastewater than the system can handle.
  • Damage to your leach field’s top layer has been caused by construction work or by cars.
  • You get a lot of rain or snow, which adds to the amount of water that needs to be filtered.
  • You have pipes that are old, rusty, cracked, or split in places.
  • You don’t pump your septic tank every few months to get rid of sludge, but you should.
  • Your pipes are clogged by plants and tree roots.

Depending on the size and needs of your home, you may need to do this a lot or not at all. Talk to an expert so that you know when you need to get the best results from your tan

Dos and Don’ts around the Leach Field

It’s not a bad idea to share space with a leach field, but there are a few things to keep in mind when you do so. Under the soil, there is a complicated system of pipes with holes in them and layers of gravel soil.

If you look at the ground around drain fields, you’ll see that most of them are flat, open areas that are far away from trees, wells, and other bodies of water.

There are some things you can and can’t do around a drain field. We’ll go over them below.


Play- Make sure your kids play games in areas far away from your septic system.

Water Sports: You can do water sports like swimming or boating over the leach field, but stay far away from the perimeter.

Landscape- Put your garden, furniture, and other decorations over the leach field.

Grass isn’t the best ground cover for a leach field. However, there are other ways to do this. If you don’t like having grass in your yard, look for plants that grow quickly and don’t spread.

They should not need any care, fertilizer, or watering. Sweet woodruff, lamb’s ear, yarrow, and golden sedge are some plants you could use. These look great and meet all of the requirements.


Pools- A swimming pool is a great way to cool off in the summer, but you should never put it over your leach field.

Be Careful with Driveways- Mixing in new concrete or asphalt can damage a leach field. That’s why you should think twice before revamping your driveway.

Heavy Lifting- You should never lift things over a septic field.

Gardens- You should not plant your garden, or allow anyone else to plant their garden over a leach field.

Why not use it to grow crops? In the end, your leach field is the worst place to do this. Gardening tools, fertilizers, and deep roots are all bad for your leach field. Microorganisms can get into food that is grown in a leach field.

Landscaping- If you plant or allow others to plant gardens, you shouldn’t grow trees or landscaping around a leach field.

Sheds and Outbuildings- If you want to build a shed or other outbuilding, don’t place it over the leach field.

Drain Field Maintenance

The septic system is usually the best place to do this work. However, that’s not always the case.

You may need to do some of this work yourself. If you do opt to do it yourself, then you should read our article on drain field maintenance.

If your drainage field doesn’t look very good in your yard, consider hiring a professional to help you out with it.

Leach Lines

After the septic tank, leach lines spread septic waste into the ground. They’re also called leach fields, filter beds, leach beds, and percolation beds, but they’re not the only things they are called.

There will be a lot of leach lines spread out across the field. The effluent will trickle through holes in the pipes and into the soil.

Leach lines are usually made of perforated PVC pipe, which makes it easier for the waste to flow into the soil. They are usually placed at least one foot below the level of the land.

The spacing between each pipe will be about six inches, but not more than three feet apart. The pipes should be spaced about every 12 inches (or less), and there should be at least two layers of pipes.

If you have a drain field that is older than five years, make sure you’ve got your leach lines inspected by a septic tank expert to make sure they’re not leaking or torn.

Advantages of a Leach Field

They are as follows:

  • Can be used to treat both blackwater and greywater at the same time.
  • Can be used in almost all kinds of weather (not when the ground freezes)
  • Has a long life (depending on conditions)
  • If you don’t have any mechanical equipment, you don’t have to do a lot of maintenance.
  • Low capital costs and low operating costs

Disadvantages of a Leach Field

They are as follows:

  • Expert design and construction are needed.
  • Some parts and materials may not be available in your area.
  • It needs a lot of space.
  • May have an effect on the properties of soil and groundwater.
  • To avoid clogs, you need to do the first thing.


What is a leach field?

A leach field is a special kind of soil to capture solids that settle in the septic tank. It’s also called a “leach bed,” “leach lines,” or “percolation bed.”

It’s a system that drains the water from blackwater and greywater using PVC pipe, gravel, and concrete. Most drain fields are made of lime rock (calcium carbonate) and perforated PVC pipes.

Why should I install a leach field?

You should install a leach field in your drain field if you or your plumber or septic tank contractor find that it’s too difficult to remove black and greywater.

What are the advantages of a leach field?

The advantages of a leach field are as follows:

  • They can be used to treat both blackwater and greywater at the same time.
  • It’s easy to build and easy to maintain.
  • They have low maintenance costs, high efficiency, and fast results.
  • They have a long life (depending on conditions)
  • It can be used in almost all kinds of weather.

What are the disadvantages of a leach field?

There are some disadvantages of a leach field, as follows:

  • It needs a lot of space, so you’ll have to get rid of more land near your septic system.
  • It may have an effect on the properties of soil and groundwater.

Can I use a leach field for my greywater and blackwater?

Yes, but you’ll have to make sure you do it according to the manufacturer’s instructions. It can be used in almost all types of weather, but you can’t use it when the ground freezes.

Which type of leach field should I install?

The drain field is better and more expensive than a leach field, but it is your best option if you don’t have any equipment or if you don’t know how to build one.

Which septic tank will I need?

You’ll need a high-efficiency septic tank if you’re using a leach field for blackwater and a low efficiency one if you’re using it for greywater.

How does the leach fieldwork?

There are several ways to explain this process, which include: The effluent (sewage) is pumped through perforated pipes that are made from PVC. The worms enter the soil. The worms feed on organic matter and return nutrients to the soil.

The water table rises, which provides oxygen to the percolation bed. The water flows through the soil and is filtered. It then travels back up through the pipe. A septic tank prevents solid waste from reaching groundwater and protects drinking water sources by enabling bacteria to break down various household wastes.

How much does a leach field cost?

The cost of a leach field depends on your location and where you live. The price for a leach field can start at about $4,800 and you’ll have to spend an extra $3,000 if you want to cover it with gravel.

What maintenance do I need to do?

You should inspect the system regularly and repair any leaks that are found.

You should also make sure none of the pipes have been crushed. The company who sold you the septic tank may be able to repair this problem, or your plumber can help you out with it.

When should I install a leach field?

Your drain field is almost ready for septic tank installation, but you should install the leach field afterward. You should install it only if your drain field isn’t working well or you find that it’s hard to remove blackwater and greywater from the drainfield.

You should also install a leach field if you have more than 0.3 acre of land and you won’t be using it. You should attach the leach lines at least 6 inches below the surface and then install perforated pipes up to 3 feet apart.

You should also install a septic tank inspection valve at the end of the leach bed. You should keep an eye on your septic tank and make sure it doesn’t clog.

When should I repair a leak?

You should repair any leaks immediately. You shouldn’t ignore them, as they can cause damage to your land, house and other things around it. You should also make sure your septic tank is level to avoid any leaks.

How big of an area is required for a leach field?

A septic tank usually needs 3 to 5 acres of land depending on the county where you live in and the size of your house and family. You need to make sure that the land you use isn’t sensitive to high water tables.

If you install a leach field and you have to pay property taxes, it’s best if you can get a reduction on your taxes or an exemption from the local government or state.

You should check with your local county assessor if this is possible in your area. You may also be able to deduct some of the installation costs for a septic tank from your income tax and save some money on yearly property taxes.

What is the life expectancy of a leach field?

It depends on the manufacturer, but most leach fields have a life span of 20 to 30 years.

How long does it take for a leach field to be ready?

The time will depend on how much concrete you need and how much time you’re willing to spend on it.

It usually takes several days, but in professional installations, it can take up to a week. The company who designed the system should make it easier for you to start your septic tank installation process.

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