An Overview: Why So Many Different Types of Systems?

Aerobic. Conventional. Low Pressure Dose. Evapotranspiration... Why so many?


These are just to name a few! And really, you can't compare the different types - its like comparing apples v. oranges. Different purposes, different needs. In fact, there are so many different types of septic systems that it will make your head spin. And if it is making your head spin, you can almost guarantee others won't know the ins and outs of the system they have, what type of system they need, or even what their options are.

No Two Systems are Alike


Seems obvious, right? Wrong. Most people assume that a septic system is just a BIG TANK IN THE GROUND WITH A PIPE STICKING OUT OF IT. Easy, right? Wrong. Each system is unique to the property and a lot goes into the design and development of the right system for your property, and it is important to realize that no systems will be identical.

Overview of (Just a Few!) System Types


  • Aerobic:Uses oxygen to increase natural bacteria activity in order to treat the wastewater. Many newer systems use this technology. NOTE: All Aerobic systems have an alarm.
  • Conventional (Trench or Bed): Consists of a tank and drainfield; this is the type of system you will typically see in older homes that have been on septic for many years, but sometimes these designs are applicable for newer builds.
  • Low Pressure Dose (LPD): Designed to treat your wastewater like a conventional system, but uses a pump to distribute treated water several times a day. This system is often confused with the aerobic systems because it too has a control panel and alarm.
  • Evapotranspiration (ET): Designed with the anticipation that all wastewater reaching the designed beds will evaporate. Most ET designs include two drain beds with a valve that alternates wastewater to one bed for a period of time before it alternates to the other bed.

Aerobic Systems

What is an Aerobic System?

What is an Aerobic System?

Wait... if my septic system is an aerobic system, does this mean it likes to work out?

Shocking, but the answer is no. But like an aerobic workout, an Aerobic Treatment Unit (ATU) uses oxygen to produce results. In the case of an ATU, oxygen is used to increase the production of natural bacteria to treat the wastewater that comes into the system. By injecting oxygen, good bacteria is put into hyper-speed, making the breakdown and processing of waste much more efficient, expediting the process of treatment.

Think about it like this: this is generally the same process that is used in a municipal setting, just on a much smaller, residential scale. Basically, you have to be able to treat the wastewater so it can effectively be re-purposed in a clean and safe manner.

How To Tell If You Have An Aerobic System

  • Does This System/Property Have A Maintenance Provider? If the answer is yes, then you probably have an aerobic system. All installed aerobic systems are required by law to have a maintenance provider, either a company or a certified homeowner. This typically consists of three visits per year to ensure the biological components of the system are working smoothly and are a health hazard to the general public.
  • Does The System Have A Control Panel? If the answer is yes, chances are the system in question is an aerobic system. Now this isn't a guarantee, as there are other types that have control panels; however this could be an easy to identify sign pointing you in the right direction.
  • Still Not Sure if You Have an Aerobic System? No problem! Give us a call. We'll be happy to do a quick and easy analysis letting us know if you have an aerobic system.

Conventional Septic Tank / Drain Field System

A Conventional System

A Conventional System

What is that?

Most everyone has heard of a Conventional Septic System, especially living in Texas. However, not many people know what it actually means. As you can guess, these are the more traditional types of systems, and are typically the most commonly used technology designed to treat wastewater.

Basically, a conventional, gravity flow system relies on just that. Gravity. It's divided up into multiple tanks or compartments, and then is re-distributed in a safe manner. Simple, right? Well, not really. You would actually be amazed at the level of science, engineering and biology that goes into the development of every system, even the conventional ones.

PROS of a Conventional System

  • Soil, or nature, provide most of the treatment. Nothing is better or healthier than using nature's natural processes. This system embraces the natural biology of soil and utilizes science in order to kill excess bacteria and pathogens, before redistributing.
  • Typically, conventional systems are the most affordable. Because of its design and how the system works, Conventional systems are typically the most inexpensive to install and to operate.
  • Conventional systems afford reliability. A conventional system, if properly installed and designed, is one of the most environmentally safe and reliable systems on the market. Nearly everyone in the industry would agree that conventional systems are one of the best options in onsite disposal.

CONS of a Conventional System

  • The types of soils that a conventional system can be installed in are VERY SPECIFIC. This means if your property has clay soil, shallow soils, or different types of soils that can become too saturated or if waste can reach the water table before being adequately treated (in gravel soils or fractured rock), a conventional system isn't for you.
  • Your system has to fit the size of your house. If you don't have a system that is big enough to support the number of bedrooms and baths you have, you can run into serious issues. This is also important if you add on to an existing structure. Your drain field must be of adequate size for your home. In some cases, there is just not enough area to support a conventional system.

Low Pressure Dose System

A Low Pressure Dose System

A Low Pressure Dose System

What is that ?

Most everyone has heard of Conventional Systems & Aerobic Systems, especially living in Texas. But have you ever heard of a Low-Pressure Dose (LPD) system?

A Low-Pressure Dose system is one that is confusing for a lot of people but is a really useful system that has a lot of versatility.

Basically, what a LPD system does, is act as a kind of hybrid between a conventional and an aerobic system. It is designed to treat your wastewater like a conventional but uses a pump to distribute wastewater several times a day, in a systematic manner, similar to an aerobic system.

Sounds simple, right? Well, that's because it is actually pretty straightforward.

PROS of an LPD System

  • ¬†LPD's have an alarm system. Now why is this a pro? Well, its simple. It lets you know if something isn't quite right & needs to be addressed. Think of a pump alarm like a check engine light - you may not know what it means, but you at least know you need to keep an eye on it and get it checked.
  • An LPD system can be installed on a variety of property types. An LPD system can be used in clay soils and relatively shallow soils. Why does this matter? Well, it allows for versatility of where this type of system can be installed. This type of system can even be designed and installed to work on sloping sites.
  • LPD systems afford reliability. Of the nonstandard drain fields, it is GENERALLY the least expensive to install and operate. Now this isn't always the case, but it is always a pro if you can save some money.

CONS of an LPD System

  • LPD's have an alarm system. Woah, woah. Now didn't we list this as a pro? Yes. But the fact that an LPD system has an alarm means it can easily get confused with an aerobic system, and if you have a service representative who, well, doesn't know what they are doing, this can cause a wrinkle in the maintenance of the system (Hence why it is ALWAYS important to ensure you get a RELIABLE & KNOWLEDGEABLE maintenance provider... not just the cheapest!).
  • There are still regulations as to where it can be installed. LPD Systems cannot be installed in soils that become too saturated during wet periods of the year or in areas where the soil is too shallow.
  • LPD systems require electrical and mechanical parts that need electricity. This means that where you have your system installed has to have electricity to not only operate it, but also requires a knowledgeable maintenance provider when a component breaks.

Evapotranspiration System

Wait... Is that really even a thing?

Wait... Is that really even a thing?

I don't think its even a word.

Shockingly, yes. Evapotranspiration (also known as an ET system) is an ACTUAL thing, and one that is actually very important to the world of wastewater. It may not seem like a real thing, but we promise - it is... So instead of it being a word with too many letters, what is it exactly?

Well, an evapotranspiration bed treats wastewater by using the loss of water from the soil (evaporation) and the loss of water from the plants growing there (transpiration). Simple? It kind of is, actually, even though the name won't make you think it is. And the whole point of an ET bed is to give the homeowner an alternate way of dealing with the filtered wastewater.

There is a lot that goes into the design of an ET system (frequency of rain, type of soil, space available on the property to build, etc.). But that isn't really something you need to worry about; those are the types of things that a qualified wastewater company can design and figure out for your home. The main thing to know is ET beds still use a standard septic system to treat the water, they only differ on HOW the wastewater is taken care of after it's treated.

One of the great things about the ET system is that it can be used in clay soil. And since we are in Central Texas, an area with abundant clay soils, an ET system could be an alternate option to an aerobic system. When you're dealing with heavy clay soils, this system can be adapted to a wide-variety of property types. However, there is a catch. If you have an ET system, you must maintain your system by pumping and manually alternating the flow of waste to fields periodically via a manual valve.

How does the water get treated? Well it is designed to treat your wastewater like a conventional system but it just uses a unique, natural way of dealing with the sanitized wastewater. As well, like a conventional system, the ET system does not require a maintenance contract.