Holding Tank vs Septic Tank: Which One To Pick?

Whether you are curious about the septic systems terminology or installing an adequate tank for your household, learning about a holding and a septic tank is good. So first, let us know the key characteristics of both and compare the holding tank vs the septic tank.

Holding Tank: Definition

holding tank in the ground

The phrase pretty much speaks for itself. A holding tank sewer system is a system that holds wastewater you make. That is the only purpose it has. Everything you flush down the drain will end up there. It will also stay there. So, the holding tank doesn’t have a way of dealing with the waste it receives. So, this is a temporary solution. When the holding tank gets full, you need to empty it.

Septic Tank: Definition

On the other hand, the septic tank is designed to hold wastewater, but it also has a leach field. So when wastewater enters the tank, some liquid parts drain into the drain field, making room for more waste. But the septic tank also has to be emptied every once in a while.

Now you know the main difference. Let us compare other characteristics to make you a holding tank vs. septic tank master.

Septic Tank Sewer System: Typical Usage

A septic system is a treatment structure buried underground, which uses a combination of nature and proven technology to treat wastewater from household plumbing produced by bathrooms, kitchen drains, and laundry. [1]

Thus, it is designed to function on its own. Normally it has two main parts: a septic tank and a leach field.

A septic tank is an underground chamber of concrete, plastic, fiberglass, or steel. Its capacity can vary from 750-gallons up to 3500-gallons. You can determine the size depending on the number of people using it and the number of bedrooms in the household.

The septic system works like this: the liquid waste from your house flows into a septic tank. It separates into three layers: solids, water, and grease. Solid waste gradually becomes sludge, while bacteria firstly break down liquid waste. Then, liquids exit the tank and go into a leach field through pipes.

A leach field (also known as a drain field) acts as a filter for contaminators in wastewater through the soil. Finally, soil treats wastewater and percolates it back into the ground.

Septic systems are often used in rural areas that are not connected to the sewerage system. You can also find it in campgrounds and picnic areas. It is believed that more than 21 million households in the United States use septic systems instead of the public sewer! [2]

Holding tank vs septic tank does not function this way. So let us find out better what its characteristics are.

Holding Tank Sewer System: Typical Usage

A holding tank is usually one big container that stores sewage from your restroom. It is often made out of plastic, but you can find the ones from fiberglass or steel. It doesn’t have any pipes or drains, so the contaminators are stored directly in it. Therefore, holding tanks need to be emptied when full.

Why and when you need to install one depends on the occasion. Holding tanks can be used in rural areas instead of septic tanks, but that is not practical. They are made of durable material, so they won’t leak (if you empty them properly). But who wants to pump out sewage every 6 to 8 weeks?

Holding tanks are mainly used for portable restrooms and vehicles like trucks, boats, trains, and spacecraft. Another thing you need to know: you can choose between different capacities. For example, if you want to attach a holding tank to vehicles, you will need less than portable restrooms or trailers. And also, larger holding tanks can have more than one access port, so if you need one, you can attach it to a couple of restrooms.

When choosing the right fit for you, it would also be good to consider factors like the daily outflow of sewage and how often you will clean it.

The Frequency of Emptying: Holding vs Septic Tank


How often you pump your tank out will vary for holding and septic tanks. But the principle is the same: you need to count the size of the tank, the number of people using them, the condition it was in before you started using it, etc.

Another very important thing you should keep in mind is what you put down the drains. It is not the same if you use a holding or septic tank as garbage disposal. Although throwing garbage in the tank is not recommended, maybe it is the only way it works for you. However, that means you will need to pump it out more often.

So, is there some average frequency of emptying both holding and septic tanks?

Some estimations show that a regularly used holding tank (average size) will need to be pumped out monthly. On the other side, if you have a really small holding tank for an RV or a boat, it may need to be pumped more often. As we said earlier, holding tanks are not designed for large households or long-term use.

Another great thing about holding tanks is that they usually have an alarm installed. This way, you won’t have to deal with the calculations – the alarm will alert you when the tank is full.

As for the septic tank, the same rule of pumping out applies: observe your habits and the size of your tank. Nonetheless, it is most common to empty it every 3 to 5 years.

What Option is Better? Holding Vs Septic Tank

It depends on what your needs are.

We recommend going with the septic system if we speak about a household. Here is why: even though the holding tank seems to cost less, that applies only to installing it. It is logical: you only have to install one container without any outlets. However, holding tanks is one of the most expensive maintenance systems. Of course, you will have to keep in mind what goes down your drains. Again, you will have to think about pumping out it regularly, and you will most likely pay a lot of money for that.

Then, of course, if you have a boat, RV, or a small cabin in the woods, it is perfectly fine to go with the holding tank. It will last for decades as long as you keep it nice and clean. Another common usage of holding tanks is when you have a portable restroom trailers company.

You get the idea: if you plan on using it on an everyday basis – choose the septic system, and if you are on the go, a holding tank is the right solution for you.

People Also Ask:


Can You Convert a Holding Tank to a Septic Tank?

If you already have a holding tank in your household, it is logical to think about switching to a septic system. A septic system is more effective, cheaper, and generally easier to maintain in the long run.

To do this, first, you need to check what license and certification you need. For example, some states require installer certification and installation permits. Maybe you will also need a professional exam. So, when you find out all the information, you can apply and wait for the permit approvals.

At the same time, you can calculate the expenses you will have during the process. Think about specific needs of your household: how many bedrooms you have, how many occupants, and how often you do your laundry. Everything counts. It will be easier to plan the septic system that fits your needs when you enumerate your expectations.

How Much Does It Cost to Pump a Holding Tank?

The price depends on the size of your tank and the service you hire. In general, the cost can vary from $100 to $500. So, it is better to have a septic tank instead of a holding tank in your household. You will need to pay to pump out more often with a holding tank, and the maintenance expenses will be higher.

On the other hand, the average price of emptying a septic tank is about $375. However, since you will probably pump out every three years, this is not a huge expense.

Why My Holding Tank Smells Bad?

Having a holding tank can have a yucky downside. If you don’t maintain it properly, it can lead to a bad odor and a potential risk of germs. To avoid a bad smell, you can take some steps to prevent it:

  • Put enough water in your tank. This way, you will ensure that waste is properly mixed with water since the dry waste is more likely to stink.
  • Avoid using a lot of toilet paper, especially the thick ones. Toilet paper can clog the pipes, and having clogs can lead to a bad odor.
  • Hire a professional service to pump out your tank regularly. By this, we mean not only to pump it out but to clean it thoroughly.
  • You can always add some holding tank treatments, for example, Thetford AquaBio Holding Tank Treatment.