What Is a Septic Inspection? Everything Homeowners Need to Know

If you’re planning to sell your home, you might be wondering if a septic inspection is necessary. Fortunately, this isn’t uncharted territory. More than 1 in 5 homes in the U.S. rely on septic systems, and in places like New Hampshire and Maine, over half of all homes are connected to one. Homes with septic systems are bought and sold every day. The key is knowing how to prepare — and that starts with understanding the inspection process. This Redfin guide covers the ins and outs here. 

What is a septic inspection?

A septic inspection is a professional evaluation of your home’s septic system to ensure it’s functioning properly and meets local health and safety standards. During the inspection, a licensed inspector will assess key components like the septic tank, distribution box, and drain field. They’ll look for signs of damage, leaks, blockages, or system failure. The inspector may also pump the tank to check sludge levels and confirm that wastewater is flowing and filtering correctly. This inspection is often required or strongly recommended during a home sale, especially in areas where septic systems are common.

What is a septic system? 

A septic system is a type of wastewater treatment and disposal system that is often used in areas where public sewage systems are not available. Typically, these are areas that are rural or on the outskirts of suburban and urban areas. 

There are many different types of septic systems, depending on factors such as what part of the country you live in, your soil type, how close the house is to specific bodies of water, the slope of your property, and how big your lot is, just to name a few. 

Typically septic systems consist of a watertight tank where raw wastewater from your home (think toilets, showers, and sinks) begins its journey to disposal. These large tanks are buried underground and can be accessed by covers, which are called risers. 

Why is a septic system inspection important?

A septic system inspection is important because it ensures the system is functioning properly and won’t create costly problems for buyers or sellers during a home sale. Undiscovered issues like leaks, blockages, or a failing drain field can lead to major repairs, lower property value, or even delay the closing process. Many buyers — and some lenders — require a clean inspection report before moving forward. By identifying and addressing issues early, sellers can avoid last-minute surprises and show that the home has been well-maintained.

Types of septic inspections

There are several types of septic inspections, each offering a different level of detail depending on the situation and local requirements. Here’s a breakdown of the most common types:

1. Routine septic inspection

A routine inspection is typically done as part of ongoing maintenance. It includes a visual check of the system’s condition, a review of maintenance records, and an evaluation of key components like the septic tank, distribution box, and leach field. 

The inspector will also check for signs of trouble, such as standing water, soggy soil, or system alarms not working. These inspections help ensure the system is operating properly and catch early issues before they become costly.

2. Point-of-sale septic inspection

This inspection is required or strongly recommended when selling a home with a septic system. It’s more thorough and time-intensive than a routine check. The inspector will locate, uncover, and pump the tank, examine its condition, and perform a flow or dye test to verify that wastewater moves efficiently from the home through the system. This inspection helps confirm that the septic system complies with local health regulations and is functioning correctly — an essential step for a smooth real estate transaction.

3. Level 3 or engineering septic inspection

A Level 3 inspection combines visual, open, and pumped inspections with additional assessments like soil percolation tests and site engineering reviews. This type is typically required in complex cases, such as new construction, system redesign, or when major septic issues are suspected.

What septic inspectors look for during an inspection

During a septic inspection, professionals evaluate several critical factors to determine if the system is functioning safely and efficiently. One of the first things they’ll assess is the age of the system and the date it was last pumped. This helps them estimate how full the tank may be — septic tanks typically need pumping every two years.

Inspectors will also ask how many people currently live in the home. The number of occupants affects how much wastewater the system must handle and whether the tank is appropriately sized. A larger household may require a larger tank to prevent overloading.

To check sludge levels, the inspector may conduct a sewer scope or similar test. If sludge accounts for more than one-third of the tank’s volume, the tank will need to be pumped. They’ll also examine the risers — the lids at ground level — to ensure they’re intact and secure. Cracked or loose lids can allow groundwater into the system or let wastewater leak out.

Another important step is checking the tank’s water tightness. It’s crucial that groundwater isn’t seeping in and that wastewater isn’t escaping into the surrounding soil. Finally, the inspector will examine the drain field to make sure there are no trees, wells, or streams nearby, as roots and water sources can damage the system’s lateral lines.

To stay on top of maintenance and avoid costly repairs, always keep records of your septic inspections and pumping history.

How often should you get a septic inspection?

Taking care of your septic system isn’t complicated or difficult. The best way to ensure your system is in peak operating condition is to have it inspected at least every three to four years by a septic professional, and yes, you should have your septic system inspected when you decide it’s time to sell. 

By having your septic system inspected frequently, you will be knowledgeable of any problems the system may have, or better yet, catch and correct any issues before they become a problem.

5 signs of septic tank problems and when you’ll need a septic inspection 

Here are some common signs that your septic tank isn’t functioning properly:

1. There is wastewater backing up into your home through your sinks and toilets.
2. You hear gurgling sounds coming from the plumbing in the house or you observe tubs and sinks draining slower than usual.
3. There are damp areas or water standing near the tank or in the drain field.
4. In dry weather, you have bright green grass growing over the top of the tank or drain field.
5. You smell a sewage odor around the area of the septic tank or out in the drain field. 

A septic system that has failed is dangerous to the health of humans and animals alike. Owners need to be aware of the signs of potential septic system failure and respond quickly by contacting a septic system professional to perform an inspection to determine the nature and severity of the problem.

5 reasons why a septic system might not work properly

Once your septic system has been designed and installed properly and is in the correct location, it’s up to you to maintain the system. Some reasons why a system might not function properly could be due to:

1. Putting items other than toilet tissue and human waste down the drain. Make sure to dispose of everything other than toilet tissue and waste in the trash.
2. Allowing vehicle traffic (or livestock) on top of the tank and lines. Know where your system is located, including the drain field, and keep traffic and livestock from damaging the components and/or compacting the soil surrounding the system.
3. Pouring chemicals down the drain to open a clog. Instead, always try a snake or hot water. If that doesn’t work, contact a septic system professional.
4. Pouring cooking grease or oils down the drain. Instead, allow them to cool and harden, and then throw them in the trash.
5. Making frequent use of the garbage disposal. Instead, compost what you can and throw the remaining kitchen waste in the garbage.

Septic inspection FAQs

1. How much do septic inspections cost?

The cost to have a septic inspection is determined by the size of the tank and how extensive the inspection is. Typically, a basic inspection ranges from $350 to $650, depending on where you live. Keep in mind that to inspect the tank, it must first be pumped, which is typically included in the price above. 

2. How long does a septic tank inspection take?

A septic tank inspection can take anywhere from a little under one hour up to three hours, depending on how elaborate your system is, and whether any problems are found. This includes the pre-pumping inspection, pumping, and the inspection that is completed once the tank has been pumped.   

4. How do you prepare for a septic inspection?

Gather any records of past inspections and pumpings to share with the inspector. Don’t pump the tank before the visit—doing so can hide signs of system issues.

5. If the septic system requires repairs, who pays for it, the buyer or the seller?

Septic system repairs are typically the seller’s responsibility, but like other inspection-related issues, they’re negotiable. The seller may choose to complete the repairs, offer a credit at closing, or leave it to the buyer, depending on market conditions. To avoid surprises, sellers can get a septic pre-certification before listing the home. This helps identify and address any issues in advance, making the home more appealing to buyers.

6. How long do septic systems last?

Septic systems typically last 20 to 30 years with proper maintenance. However, poor upkeep—like skipping inspections, overloading the system, or damaging it with vehicles or tree roots—can significantly shorten their lifespan. Regular care is key to maximizing longevity.   

7. Is it hard to sell a house with a septic system?

Concerned about selling your house with a septic system? Don’t be. Remember, homes with septic systems make up about 20 percent of all homes in the United States right now. So, unless your system is at the end of its lifespan, or has never been maintained and is failing, you should have no concerns about selling your house. 

8. Can I sell my house with a failed septic system?

It depends on where you live—some states prohibit selling a home with a failed septic system. In areas where it’s allowed, you’ll likely need to lower your asking price and provide repair estimates. If the buyer is using a mortgage, their lender may require proof the system has been fixed before closing. Always check with your real estate agent for local requirements.

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