Pumping a Septic Tank: What You Should Know

Septic systems are installed in about 1 in 4 homes in the U.S., and they are especially prevalent in rural areas that are not served by municipal sewer service. Rather than pumping waste through sewer mains to a central sewage treatment facility, a septic system pumps solid and liquid waste from the house out into a drain field and underground septic tank.

How to Care for Your Septic System

Septic system maintenance is not complicated, and it does not need to be expensive. Upkeep comes down to four key elements:

For more about septic system maintenance, see answers to frequent questions on caring for septic systems.

Inspect and Pump Frequently

The average household septic system should be inspected at least every three years by a septic service professional. Household septic tanks are typically pumped every three to five years. Alternative systems with electrical float switches, pumps, or mechanical components should be inspected more often, generally once a year. A service contract is important since alternative systems have mechanized parts.

These are the major factors that influence how often to pump your septic system:

• Household size
• Total wastewater generated
• Volume of solids in wastewater
• Septic tank size

Here is what you need to know for a service provider

When you call a septic service provider, he or she will inspect for leaks and examine the scum and sludge layers in your septic tank.

Your septic tank includes a T-shaped outlet which prevents sludge and scum from leaving the tank and traveling into the drainfield area. Your tank should be pumped if the bottom of the scum layer is within six inches of the bottom of the outlet, if the top of the sludge layer is within 12 inches of the outlet, or if more than 25% of the liquid depth is sludge and scum.

To keep track of when to pump out your tank, write down the sludge and scum levels found by the septic professional.

The service provider should note repairs completed and the tank condition in your system’s service report. If other repairs are recommended, hire a repair person soon.

Use Water Efficiently

The average indoor water use in a typical single-family home can be as much as 70 gallons per individual, per day. Just a single leaky or running toilet can add as much as 200 gallons of water per day.

All the water a household sends down its pipes ends up in its septic system. The more water a household conserves, the less water enters the septic system. Efficient water use improves the operation of a septic system and reduces the risk of malfunctions.

EPA’s WaterSense program has many simple ways to save water and water-efficient products.

• High-efficiency toilets. Toilet use accounts for 25 to 30 percent of household water use. Many older homes have toilets with 3.5- to 5-gallon reservoirs, while newer, high-efficiency toilets use 1.6 gallons of water or less per flush. Replacing existing toilets with high-efficiency models is an easy way to reduce the amount of household water entering your septic system.
• Faucet aerators and high-efficiency showerheads. Faucet aerators, high-efficiency showerheads, and shower flow restrictors help reduce water use and the volume of water entering your septic system.
• Washing machines. Washing small loads of laundry on your washing machine’s large-load cycle wastes water and energy. By selecting the proper load size, you will reduce water waste. If you are unable to select a load size, run only full loads of laundry. Try to spread washing machine use throughout the week. Doing all household laundry in one day might seem like a time-saver but it can harm your septic system. It will not allow your septic tank enough time to treat waste and could flood your drainfield. Clothes washers that bear the ENERGY STAR label use 35 percent less energy and 50 percent less water than standard models. Other Energy Star appliances provide significant energy and water savings.

Properly Dispose of Waste

Whether you flush it down the toilet, grind it in the garbage disposal, or pour it down the sink, shower, or bath, everything that goes down your drain ends up in your septic system. What goes down the drain affects how well your septic system works.

Toilets aren’t trash cans!

Your septic system is not a trash can. An easy rule of thumb is not to flush anything besides human waste and toilet paper. Never flush:

• Cooking grease or oil
• Non-flushable wipes, such as baby wipes or other wet wipes
• Photographic solutions
• Feminine hygiene products
• Condoms
• Dental floss
• Diapers
• Cigarette butts
• Coffee grounds
• Cat litter
• Paper towels
• Pharmaceuticals
• Household chemicals like gasoline, oil, pesticides, antifreeze, and paint or paint thinners

Think at the sink!

Your septic system contains a collection of living organisms that digest and treat household waste. Pouring toxins down your drain can kill these organisms and harm your septic system. Whether you are at the kitchen sink, bathtub, or utility sink:

• Avoid chemical drain openers for a clogged drain. Instead, use boiling water or a drain snake.
• Never pour cooking oil or grease down the drain.
• Never pour oil-based paints, solvents, or large volumes of toxic cleaners down the drain. Even latex paint waste should be minimized.
• Eliminate or limit the use of a garbage disposal. This will significantly reduce the amount of fats, grease, and solids that enter your septic tank and could clog the drainfield.

Maintain Your Drainfield

Your drainfield—a component of your septic system that removes contaminants from the liquid that emerges from your septic tank—is an important part of your septic system. Here are a few things you should do to maintain it:

• Parking: Do not park or drive on your drainfield.
• Planting: Plant trees the appropriate distance from your drainfield to keep roots from growing into your septic system. A septic service professional can advise you of the proper distance, depending on your septic tank and landscape.
• Placing: Keep roof drains, sump pumps, and other rainwater drainage systems away from your drainfield area. Excess water slows down or stops the wastewater treatment process.

Frequent Questions on Caring for Septic Systems

• Should I be careful of what I pour down the drain?
  • Yes. Many materials that might be poured down the drain do not easily decompose. This can be harmful to the healthy bacteria that grow in your septic tank and drainfield to help break down organic matter. Do not pour grease (such as fats, butter, wax, cheese, heavy cream), liquid wastes (such as pesticides, drain cleaners, household chemicals, paints, paint thinners), oils or coffee grounds down the drain. If you have a garbage disposal, limit its use because food waste can add an unnecessary amount of solid material to your septic tank. Harmful chemicals put down your drain can also be discharged into the groundwater and can impact drinking water supplies and the environment. EPA’s Quick Tip Video explains which items to put or not put down the drain, “Think at the Sink!”
  • Yes. Using an in-sink garbage disposal unit can impact how often you need to pump your septic tank. Food waste usually is slowly digested by the healthy bacteria in your septic tank and can accumulate as scum and sludge. If a large amount of water enters the septic tank or the tank fills up with solids, it can push the solids into the drainfield, causing the pipes to clog and increasing the thickness of the biomat (a bacteria layer that forms on the bottom and sides of the drainfield trenches). If you must use a garbage disposal unit, your tank will need to be pumped more frequently.
  • Only flush human waste and toilet paper down the toilet.
  • Never flush these items down the toilet because they could clog your septic system and cause a failure:
    • Cooking grease or oil
    • Non-flushable wipes, such as baby wipes or other wet wipes
    • Photographic solutions
    • Feminine hygiene products
    • Condoms
    • Dental floss
    • Diapers
    • Cigarette butts
    • Coffee grounds
    • Cat litter
    • Paper towels
    • Pharmaceuticals
    • Household chemicals like gasoline, oil, pesticides, antifreeze, and paint or paint thinners
    • Yes. Most drainfields (such as rock and pipe, chamber system, etc.) are constructed in open lawn areas and are not designed to handle vehicles or heavy equipment driving on them. The weight of vehicles and heavy equipment compacts the soil, which can damage pipes. Impermeable materials, such as concrete and asphalt, should not be laid on top of a drainfield because they reduce evaporation and the supply of oxygen to the soil. Oxygen is critical to the healthy bacteria in your septic system and the proper breakdown of sewage by soil microorganisms.
    • Do not build any structures in or on your drainfield area without checking with a local designer or permitting authority. It is not recommended to plant trees, shrubs, or vegetable gardens on the drainfield. Tree and shrub roots can ensnarl and damage drainfield pipes. Vegetables can potentially be exposed to sewage effluent and unsafe to consume. Native grasses and ground covers are the most appropriate planting over your drainfield. See EPA’s Proper Landscaping On and Around Your Septic System factsheet or WaterSense’s What to Plant for more information.
    • EPA’s Quick Tip Video explains how to safeguard your drainfield, “Shield Your Field!”
    • Septic Systems Home
    • About Septic Systems
    • Care and Maintenance
      • How to Care for Your Septic System
      • Why Maintain Your Septic System
      • Resolving Septic System Malfunctions
      • Septic System Impacts on Water Sources

      Pumping a Septic Tank: What You Should Know

      Aaron Stickley is a licensed plumber with 15 years of experience in commercial, new residential plumbing, and residential service and repair. He started his own residential service and repair plumbing business. Aaron’s articles about plumbing on The Spruce span four years.

      

      Richard Epstein is a licensed master plumber with over 40 years experience in residential and commercial plumbing. He specializes in estimating as well as design and engineering for plumbing systems, and he works for one of New York’s largest union plumbing construction companies.

      Septic systems are installed in about 1 in 4 homes in the U.S., and they are especially prevalent in rural areas that are not served by municipal sewer service. Rather than pumping waste through sewer mains to a central sewage treatment facility, a septic system pumps solid and liquid waste from the house out into a drain field and underground septic tank.

      

      How Septic System Works

      In a traditional septic system, all water and wastes carried by that water flows down the home’s drain system and through one main sewer pipe to the septic tank. The flow of wastewater may be a matter of simple gravity, or it may be enhanced with an electric pump. The septic tank holds the waste material long enough for the solids to settle to the bottom as oil, grease, and liquids — the scum later — float to the top. When the tank reaches capacity, the liquids lying on top of the scum later flow onward into a series of porous pipes to a drain field prepared with gravel and other aggregates that helps disperse the liquid waste. The liquids slowly filter down through the soil as bacterial action breaks down the pathogens. By the time the liquid waste filters down to groundwater supplies, it is virtually sterile.

      Meanwhile, the solids in the tank break down under the affect of anaerobic bacteria, creating a sludgy material that collects in the bottom of the tank. If the bacterial action is effective, these solid wastes are greatly reduced in volume as they break down.

      

      Anatomy of a Septic Tank

      The septic tank water-tight container made of concrete, fiberglass, or polyethylene buried in the ground in an area near the house. It includes an inlet pipe where all waste from the home’s sewer pipe enters the tank and an outlet pipe that allows liquids to flow onward to the drain field. The top of the tank is buried slightly under the surface of the soil, invisible except for one or two inspection tubes and a manhole cover that is used to pump the sludge from the tank when it becomes necessary.

      When to Have Your Septic Tank Pumped

      The EPA recommends that a septic tank should be inspected every two to three years, with mechanical pumping typically required every three to five years to empty the tank. Systems that are undersized or that see very heavy use may require pumping annually. Some systems have electrical float switches, pumps, or mechanical components, and these need to be inspected more often, typically once each year.

      Pumping is the process of removing sludge from the bottom of the septic tank, and this needs to be done before the sludge builds up to a level where it blocks the outlet pipe through which liquids flow into the drain field. The frequency with which this needs to be done depends on several factors:

      • Size of household: Larger households, predictably, generate more waste, and thus fill up the septic tank faster.
      • How much wastewater is generated: The sheer volume of wastewater flowing into the septic tank can affect how fast the septic tank fills up.
      • The volume of solids in the wastewater: Households with many toilets, or who make frequent use of garbage disposals, tend to fill up the septic tank quicker.
      • Septic tank size: Larger tanks can hold more solid sludge, and thus will need less frequent pumping.

      There are ways to help estimate about when you should have your tank pumped. As an example: an average four-bedroom house may have a 1,200 to 1,500 gallon tank and with a family of four, you should expect to have the tank pumped every 3 to 5 years with typical use.

      How a Septic Tank Is Pumped

      If you have a septic service professional who inspects your septic tank regularly, they will tell you when it is time to pump out the sludge from the tank. Generally, this is when the floating scum layer that lies between the sludge and the floating water is within about 6 inches of the outlet pipe leading to the drain field.

      The septic service arrives with a large tanker truck with vacuum equipment, and technicians insert a large hose into the septic tank through the manhole after the cover is removed. As the truck’s equipment sucks out the contents of the septic tank, a technician usually stirs the contents of the tank with a muckrake to break up the solids and mix them with the liquid material to make pumping more efficient. Costs for pumping a septic tank range from $200 to $500 depending on the region in which you live and the size of the septic tank.

      Tips for Maintaining Septic System

      There are several proactive measures you can take to ensure that your septic system operates efficiently and to reduce the frequency with which pumping is necessary:

      • Reduce water usage. Using high-efficiency, water-saving plumbing toilets and faucets can greatly decrease the amount of water that goes into the septic system. Repairing leaks and drips is another way to reduce the overuse of water that can cause the septic tank to fill faster.
      • Reduce solid wastes: Monitoring the solid waste that enters the septic system is another way to keep it working properly. Trash that is either washed or flushed down the drain can overburden the septic system. Don’t flush anything other than toilet paper down the toilet, and avoid using a garbage disposer that puts organic food wastes into the septic system. Throwing things in the trash takes only a little effort, but it will make a big difference in the management of the septic system.
      • Direct rainwater away from the drain field. Downspouts and landscape grading that funnel water onto the septic system’s drain field can interfere with its ability to disperse water from the septic system.
      • Don’t drain hot tubs into the drain system. This can put undue stress on the septic system; instead, drain water from hot tubs or swimming pools into the yard, away from the drain field.
      • Avoid putting chemicals down the drain. Chemicals can interfere with the bacterial action that breaks down solid wastes, so avoid flushing them down the drain. This also includes various commercial septic tank additives, which generally do more harm than good. Unless a trusted professional has prescribed such an additive, don’t use any septic tank chemicals.

      The Spruce uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

      1. US EPA, OW. “How to Care for Your Septic System.” Overviews and Factsheets, June 16, 2015. https://www.epa.gov/septic/how-care-your-septic-system.
      2. US EPA, OW. “How Your Septic System Works.” Overviews and Factsheets, June 16, 2015. https://www.epa.gov/septic/how-your-septic-system-works.