Sewer Cleanout Cap Popped Off?

Homeowners are usually concerned about keeping their sewer systems in good working order, including keeping an eye out for unusual events. One of the most concerning things that might happen to your sewage line is to have the sewer cleanout cap popped off unexpectedly.

A loose cap or obstructions in your sewer line system might cause a popped-off cleanout cap. This can lead to spills outside your home and significant septic system damage. You’ll be better off if you fix the piping system as soon as possible. 

Although it may be a minor issue, a sewer cleanout cap popped off can indicate severe problems that will only worsen if not fixed. This article will help you understand what might happen if you don’t handle the issue, as well as offer possible solutions to the problem.

What is a sewer cleanout plug?


A sewer cleanout plug is a detachable cap that allows you or licensed plumber access to it [1]. If it’s missing or broken, though, there are a few things that can go wrong with your sewer system:

  • Rainwater can get inside and cause rust and corrosion;
  • Dirt and debris can cause blockages.
  • It is also possible for little animals to get stuck within and clog the sewer line;
  • Reduces the lifespan of your sewer system

Without a sewer cleanout cap, hazardous and non-toxic gases such as methane and hydrogen sulfide can escape the sewer system and enter your home, causing a foul odor.

A plumber uses a sewer line camera to inspect the condition of your drain in an effort to address any existing problem [2].

The sewer line camera can cost anywhere from $250 to $1,175. And depending on the approach used, cleaning the sewer line to remove the accumulated dirt can cost anything from $100 to $600.

So naturally, completing the work before releasing wastewater into the sewer system will save you both time and money.

How do you remove a sewer cleanout cap? 



You will need to remove the sewer cleanout plug if you wish to clean the drain pipes. Some sewage cleanout caps are simple to remove, while others are more difficult. It’s typical for certain plugs to rust and get stuck to the threads over time, making replacement almost impossible. This happens more frequently with cast-iron fittings, although it can also happen with plastic ones. But you will need to know the sewer cleanout location before you remove it.

If your sewer cleanout plug is stuck, consider the options below for unscrewing it:

  • Elbow grease: Sometimes, all that’s needed is a little bit of grease to smoothen the thread and get the cap to come off. But be cautious. You better leave it if unscrewing it feels like you are using too much force.
  • Heat: Using heat to loosen up any rigid material has always been beneficial. To loosen the threads on cast-iron fittings, use a propane flame. If you have a plastic fitting, avoid using a torch and instead use a hairdryer. And always be careful in handling the flame to avoid burning yourself.
  • Penetrating catalyst lubricant: If the threads on the plug are locked together due to corrosion, you can use a penetrating catalyst lubricant to free them. Because the lubricant is an explosive chemical, it should not be used carelessly or where other cheaper options exist.
  • Hammer: You should be able to detach the sewer cleanout cap with a few taps with a framing hammer or sledgehammer.
  • Wrench: If you place a wrench on the plug’s nut and crank it counterclockwise, you may be able to loosen it up enough to remove the cap.

In case none of these approaches successfully removes the sewer cap, consider cutting out the fitting and replacing it. In case you lack the skill to cut it yourself, get a sewer line servicing expert to do it for you. It’s worth mentioning that the threads on the existing plug won’t hold a new one if the sewer pipe cap has jammed. So to get the threads to seal correctly, you may need to apply a rubber coupling.

A sewer cleanout cap popped off may be caused by two factors.

First, most people leave their cleanout caps loose. When a sewer cleanout plug is loose, pressure may build up in the system and cause it to pop off. Even strong winds might cause it to pop off. For this reason, it is advisable to tighten the plug to prevent it from popping off and going missing.

Secondly, the sewer cleanout cap popped of can occur as a result of the sewer drain getting clogged. The pressure that accumulates in the drainpipe as it fills up with the effluent flowing backward might cause the plug to pop off. Sewage spills might even occur within or outside your house in many circumstances. This can also happen if any tree growing near the sewer pipes pushes its root through the sewer lines and causes damage.

Should you leave the sewer cleanout plug loose?

Some folks might opt to leave the cap loose in an endeavor to avoid sewer cleanout cap leaking and backflow reaching their house. This way, they hope to direct the overflow into the yard rather than allowing it to flow into the house.

In some jurisdictions, it is against the existing building code to leave the sewer cleanout plug loose. However, this might be more the exception than the rule. Consider checking your local construction regulations to make sure you are on the right side of the law.

 How to Fix Sewer Cleanout Cap Popped off

First of all, all it might take to fix a sewer cleanout cap popped off is to tighten it back in place. If the cap does not stay in place, clean up any obstructions or excess material that may be causing this problem.

Perhaps the reason why the sewer plug keeps popping off is the backflow or clogging of the sewer line. Cleaning the drain, in this case, is the best solution. If you have a snake tool, you can use it to fix the problem by cleaning the drain yourself [4]. However, cleaning out some gutters might not be as simple. If you’ve already snaked your sewer cleanout and still haven’t figured out what’s wrong, you might need to hire professional help to diagnose and fix the problem.

Before taking any further action to clean out the sewer drain, consider turning off the water supply to your home as well as any water appliances you may have. Cleaning out a sewer drain while wastewater is still flowing will make the situation worse. If it comes to replacing your broken sewer pipe cap, keep these helpful guidelines in mind to ensure that the job runs smoothly.

  1. Select the correct plug size: The first step in getting a replacement plug is to know what sort of plug you require. So, to begin, measure its length, which can range from one-half to four inches. To precisely check the dimensions of the plug, it is recommended that you use a measuring tape.
  2. Determine the type of material to use: You may determine what kind of material the sewer cap is composed of based on how much of it remains before purchasing a new one. Most sewer cleanout caps are made from metal, ABS, or PVC. The sewer pipe cap is often composed of the same material as the pipe. As a result, double-check the pipe material to see what you require.
  3. Diagnose the problem as soon as possible. Some might think that there’s no need to rush if the cap has popped off, as long as your sewer lines are still operational. However, if you realize that your cap is no longer protecting your sewer cleanout, you’ll need to gather the essential components and repair them immediately.
  4. Be cautious when removing a broken cap. Removing the cleanout cap can potentially discharge pressure built up in the sewer system if the drains are clogged. This implies that you need to examine the system to determine whether or not there is a blockage and how your cap broke and how the cleanout plug popped off in the first place.

Who should I approach if my sewer cleanout cap popped off?

Getting someone to help you fix your popped-off sewer cap depends on the options available in your locality. In most cases, you will have to foot the bill to repair your sewer system. For this reason, the best course of action is to contact a professional plumbing company and get them to assess the situation. Then, they will advise you on what needs to be done to handle it.

In certain regions, however, homeowners are only responsible for the portion of the sewer system above the ground. If this is the situation in your community, phoning the sewer company might save you some money.

What will it cost to repair your sewer cleanout plug popped off?


The cost of fixing the issue causing the sewer cleanout lid to come out depends on the severity and where you live. A typical job will cost between $175 and $550 to clean a sewer cleanout line. You can expect to spend between $600 and $2000 if your sewer cleanout needs to be replaced due to excessive damage.

The cost of repairing your sewer cleanout is determined by the level of excavation required. Because your sewer system has many underground connections, jobs that require underground access will necessitate excavation. This can result in a substantially higher cost and more time spent on the project.

What will happen if I don’t address this problem?

Although this may appear like a minor issue, it should not be overlooked. Your sink, tub, and toilet may drain slowly due to clogging. If left unattended, the blockage will increase to the point where sewage will be unable to reach the septic tank. Flooding and backups will occur within your home as a result of this.

Of course, the most severe case will be the risk of permanently damaging your sewer system. If this happens, you might be forced to replace the entire system, proving to be a very costly exercise.

Final Thoughts

Hundreds of people are faced with the problem of having their sewer cleanout cap popped off every day. However, not many have an idea how to fix it. Plumbing is usually a dreary, dark, and wet topic that no one wants to think about. For such people, knowing where and how to find help to fix the problem would make all the difference in the world. Hopefully, this blog provides the necessary advice to keep your sewer system working like a charm.