A Simple Homeowner Guide

If your home isn’t connected to a city sewer, it likely uses a septic system. Septic systems safely treat and dispose of wastewater right on your property. When designed, installed, and maintained properly, they can work reliably for decades. When ignored, they can become one of the most expensive surprises a homeowner faces.

This guide explains what a septic system is, how it works, what parts it has, common problems we see, and how I test it during a home inspection.

Septic systems are used in areas where municipal sewer service isn’t available—most commonly rural properties or homes outside city limits (very common throughout Indiana).

Instead of sending wastewater to a distant treatment plant, a septic system:

• Treats wastewater on site
• Uses gravity, bacteria, and soil filtration
• Returns clean, filtered water back into the ground

Septic systems are approved and regulated by county health departments and are designed specifically for the soil and conditions of the property.

This is a buried, watertight concrete or plastic tank, usually located 10–25 feet from the house.

Inside the tank:

• Wastewater enters from the home
• Solids settle to the bottom (called sludge)
• Grease and light materials float to the top (called scum)
• Clear liquid in the middle flows out to the drain field

Key internal components:

• Inlet baffle – slows incoming waste so it doesn’t stir up the tank
• Outlet baffle – keeps scum and solids from leaving the tank
• Normal water level – should remain steady if the system is working correctly

The tank’s job is separation, not disposal.

After leaving the tank, wastewater flows into a distribution box. This evenly sends water into multiple drain lines so no single area gets overloaded.

This is where treatment finishes.

• Perforated pipes sit in gravel trenches
• Wastewater slowly seeps into surrounding soil
• Soil naturally filters bacteria, nutrients, and contaminants

A healthy drain field:

• Drains evenly
• Stays relatively dry at the surface
• Supports normal grass (not dark, soggy patches)

A typical septic system lifespan is 20–30 years, assuming:

• Regular pumping
• Reasonable water usage
• No damage to the drain field (do not drive over the septic field)

That said, we do see systems locally in Indiana that are 40–50+ years old and still functioning. Those longer-lasting systems usually share a few things in common:

• Conservative water use
• Large drain fields
• Good soils
• Consistent maintenance

On the flip side, systems can fail much earlier if they’re never pumped or are overloaded.

Because replacement costs are significant—often in the $10,000–$20,000 range—understanding the condition of an existing system is extremely important when buying a home.

Septic systems are not sized by house square footage.

They are usually sized based on:

• Number of bedrooms (used as a proxy for daily water use)
• Soil type and percolation rate
• Local health department standards

Typical examples:

• 3-bedroom home → ~1,000–1,250 gallon tank
• Larger homes → larger tanks and drain fields

If a home has added bedrooms or plumbing fixtures without upgrading the system, problems often follow.

In Indiana, we most commonly see:

• Most common
• Tank → distribution box → drain field
• Works best in well-draining soils

• Used when soil doesn’t drain well or water table is high
• Drain field is built above natural grade
• Requires careful water usage

• Uses a pump to evenly distribute wastewater
• Helps protect the drain field
• More components = more maintenance

• Uses oxygen to help break down waste
• Often required in sensitive areas
• Needs electricity and regular service

Septic systems should be on file with the county health department. These records often include:

• Original permit
• Tank size
• Drain field location
• System type
• Soil evaluation

However, records are sometimes:

• Incomplete
• Missing (usually before the 1970's)
• Incorrect
• Never updated after modifications

Knowing where the system is located is critical for:

• Maintenance
• Additions
• Driveways, decks, or pools
• Avoiding costly damage

Many systems fail simply because they were never maintained. Tanks typically need pumping every 2–3 years, depending on usage.

Without a riser, access lids are buried. This leads to:

• Skipped maintenance
• Difficult inspections
• Higher service costs

Often caused by:

• Full tank
• Blocked outlet baffle
• Failing drain field

Signs include:

• Standing water
• Soggy soil
• Dark green grass
• Odors

Drain field replacement is one of the most expensive septic repairs, often reaching five figures.

A septic inspection is about reducing uncertainty, not predicting the future.

Here’s what I typically do:

• Review available health department records
• Look for visual surface clues
• Probe the yard to locate the septic tank
• Use a sewer camera when necessary to confirm layout

• Open the tank when accessible
• Measure scum and sludge levels
• Check inlet and outlet baffles
• Confirm proper operating water level

• Introduce a minimum of 300 gallons of water 
• Use food-safe dye to help trace flow through the system
• Observe how the tank and drain field respond

• Walk the entire drain field area after testing
• Look for surfacing water, odors, or stressed areas
• Note abnormal vegetation patterns

I focus on explaining:

• What is functioning normally
• What needs maintenance
• What needs further evaluation
• What’s typical for the system’s age

A septic system isn’t something to fear—but it does require understanding and routine care.

A good inspection doesn’t just look for failure—it helps you:

• Understand how your system works
• Plan maintenance instead of reacting to emergencies
• Make informed decisions about a major investment

When properly cared for, septic systems can serve a home reliably for decades—even generations in some Indiana properties.

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