How to Check If Septic Tank is Full

Last Updated On June 11, 2024

Updated on April 25, 2023



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How to Check If Septic Tank is Full

Do you suspect your septic tank might be full? Your septic tank system offers an efficient wastewater solution that also contributes to a self-sufficient lifestyle.

However, septic tanks require regular maintenance just like anything else.

Material, scum, and solid waste accumulate inside the tank over time, and can exceed recommended levels. Once the septic tank becomes full, you will need to hire a professional to pump the septic tank. Sorry, this isn’t a DIY task!

In this PlumbingNav guide, we will cover:

  • How to check if a septic tank is full
  • What to know about full septic tanks
  • How to properly maintain and avoid full septic tanks

What's In This Guide?

      How to Check if a Septic Tank is Full?

      You can inspect your septic tank at one of the access points in your yard. Many installations have something known as septic tank risers. The risers are pipes that extrude up from the ground from the septic tank and look like manhole covers. See this post for how to find your septic tank lid.

      Risers have covers that are easy to remove with a few screws. When you remove it, you can then access a cement cover to get a good view of the contents inside. 

      There will always be some material in the septic tank. The tank collects the contents of all of the toilets, drains, and plumbing appliances in your home, such as your washing machine and dishwasher. 

      did you know how do you know if septic tank is full

      How do you actually measure septic tank waste?

      The obvious issue to initially check is that waste levels don’t exceed the outlet pipe. When you open the septic tank lid and look into your riser, the material inside should not be above the outlet pipe which allows water waste to flow into the drain field. This would signal the need for immediate attention.

      The other not-so-obvious things to check involve measuring the scum and solids. Here is what that means…

      Take note of the level of “scum” level on the top of the water which consists of grease, fats, and other items that fail to break down with bacteria. (See more here about how a septic tank works.) 

      Then, you’ll also want to measure the amount of solid waste called “sludge” toward the bottom of the tank as well. This can be challenging, as visibility is of course limited. Some homeowners find it easier to use a tool specially designed for this task. (See below.)

      Add these two levels together, and confirm that the combined total isn’t more than ~30% of the tank’s volume. If it is larger than this, your septic tank is “full.”

      What tool should you use to check septic tank levels?

      There are some homemade options out there, but the best and most reliable tool to check if your septic tank is full is called a “sludge judge.” You can buy one on Amazon that also comes with a case to cleanly store it while not in use. Wear gloves!

      Here is a video of how to use the “sludge judge” tool linked above:

      Click here to check the price of the “Sludge Judge” product shown in this video.

      Here is a video showing you how to check if your septic tank is full, and also how to make some DIY tools:

      You may notice signs of a full septic tank before you perform a septic tank inspection yourself, including:

      If you notice these problems around your home, the septic tank requires septic pumping.

      What to Know About Full Septic Tanks 

      A residential septic system treats waste coming from your home, including toilets, sinks, and appliances such as washing machines and dishwashers. Septic systems replace standard waste management throughout the city limits. Homeowners save money, but they must take on the responsibility of maintenance.

      What is meant by “waste” levels in a septic tank?

      The waste in a septic tank separates into three levels:

      • Top level – scum (oils, fats, grease, and foreign items)
      • Middle layer – liquid waste (effluent)
      • Bottom layer – solid waste (sludge)

      Effluent wastewater escapes the tank through an outlet pipe into a drain field. The waste mixes into the soil, acting as a natural fertilizer. Natural enzymes and bacteria dissolve the solid waste. 

      The top scum layer must be removed from time to time by a professional septic tank company or plumber if it exceeds recommended layers. 

      The sludge layer is last to dissolve and accumulates in the tank if there is too much volume entering the tank, or if bacteria levels have been disturbed to slow decomposition.

      Common culprits might be extended family members staying in a home rated for fewer occupants, or chemical cleaning agents such as bleach poured down the drain that works against the natural septic process.

      Homeowners cannot perform septic tank pumping themselves. Septic plumbing services must be completed by a professional. 

      You can prevent your septic tank from becoming too full and often prolong the need for pumping by using a septic tank treatment. Treatments add helpful bacteria and enzymes into your septic tank to ensure the material dissolves properly. 

      You should use a septic treatment as directed as part of your regular septic tank maintenance in between cleanings. You will not need to clean the tank as often, saving you money and ensuring proper operation of the septic tank. (All things equal, of course.)

      You should also avoid certain types of toilet paper, and use a product that breaks down easily. While less common, some households are opting to use a bidet. This eliminates the TP issue altogether.

      How to Locate Septic System to Check a Full Tank

      In order to check your own septic tank, you should learn the location of your septic tank risers. 

      The septic tank risers in your yard protrude up from the ground, so they should be relatively easy to find. If your system does not use risers, look on the land survey or check with the county. These records are often publicly accessible and will be nice to place in your file cabinet. 

      This is also a great way to identify the placement of your drain field. It’s important to keep both vehicles and property improvements a safe distance away. 

      What to know about calling a septic company to check if the tank is full

      According to the EPA, septic systems should be checked every 1-3 years and pumped every 3-5 years. 

      While professionals must perform the pumping, you can inspect the system yourself. The average cost to pump a septic tank is between $350 – $400, depending on the location and the size of the tank.

      How to Properly Maintain & Avoid Full Septic Tanks

      As scum is the most difficult problem, you should make a point not to pour fat, grease, and oil down your drain. Instead, pour the contents into containers and throw them away in the garbage when they become full. 

      You should also be careful of what you put down the garbage disposal, for the sake of your drains and septic tank. Fibrous vegetables, shells, peels, and coffee grounds should not go down the garbage disposal!

      Furthermore, you should use a septic tank treatment regularly. A septic tank treatment works similarly to a drain cleaner. However, it does not attack clogs. 

      Most septic tank treatments derive from enzymes similar to natural drain cleaners or probiotics. These either dissolve organic material or balance the bacteria levels in the tank to promote the natural decomposition of the organic material.

      Why You Shouldn’t Ignore A Full Septic Tank

      If you ignore a full septic tank, you leave yourself vulnerable to an unpleasant and potentially hazardous septic tank problem. If nothing else, it will only create a much more expensive problem down the road.

      You don’t want to experience a sewage backup, possibly not covered by insurance if you ignored it. 

      Some of the other things that may occur as a result of a full septic tank include:

      Final Thoughts on How to Check Septic Tank Levels

      There are a lot of advantages to having a septic tank. However, to make the most of the private setup, you need to prevent the tank from filling up past safe limits. It’s both a handy and cost-saving investment to inspect the septic tank to ensure it’s not full. Be prepared to schedule septic tank pumping every 3 – 5 years, even if you take good care of your septic system.

      FAQ’s on Full Septic Tanks

      How do I know when my septic tank is full?

      You can visually inspect the contents of your septic tank by opening one of the septic tank riser covers in your yard. Look inside to verify the material isn’t higher than the outlet pipe. It’s best to use a sludge judge to measure both scum and sludge levels, ensuring they are not more than 30% of your total tank volume. 

      What are the signs of a full septic tank?

      You may also find signs of a septic tank being too full without going outside to inspect the tank. You may need your septic tank emptied if you notice a pool of water developing in your yard, a foul odor, a slow drain, or toilets not flushing right.

      How often should a septic tank be emptied?

      According to the Environmental Protection Agency, your septic tank requires plumbing every 3 – 5 years. You should inspect the septic tank every 1 – 3 years.

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      We write about “all things plumbing,” helping you navigate common questions, repairs, and the best plumbing products on the market.

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