A lagoon septic system is made up of two components: the septic tank and a lagoon.
Effluent undergoes primary treatment in the septic tank after which it is sent to a lagoon where wind, sunlight, and temperature finish the treatment process.
The lagoon is a small pond that is typically 3 feet deep.
Lagoon septic systems are usually installed in regions that have poor soils that would support conventional systems.
However, the pond needs to be a good distance from the house and that means this system only works on properties that have enough space.
Lagoon Septic System Installation Cost
Lagoon systems are relatively inexpensive alternate systems, especially in rural settings where land is cheap.
Installing a lagoon septic system is way cheaper than installing a drip system.
A lagoon septic system can cost anything from $2,500 to $15,000.
However, the cost can go higher if the system is not for a residential property (e.g. a campground) as that will call for a larger system.
| Lowest price | $2,500 |
| Average price | $8,000 |
| Highest price | $15,000 |
Lagoon Septic System Cost By Size
Just like a conventional septic system, a lagoon system’s size is informed by the number of users.
As you may imagine, larger systems will cost more to install because they need more materials, components, as well as labor.
The table below gives a breakdown of the different lagoon system sizes based on house occupancy.
| Number of bedrooms | Septic tank capacity | Lagoon size in square feet |
| 1-2 | 1000 gallons | 900 |
| 3 | 1000 gallons | 1,320 |
| 4 | 1250 gallon | 1,760 |
| 5 | 1500 gallons | 2,200 |
A 1000-gallon septic tank costs around $1200 to install while a 1500-gallon tank costs around $1800 to install.
The size of the septic tank coupled with the size of the lagoon pond will make the price fluctuate proportionally.
For instance, a small lagoon pond may cost around $2,000 while a larger one may be thrice as much.
Other Factors That Affect Lagoon Septic System Cost
1. Permits
A lagoon construction permit may be required by the local authority.
The cost of this permit differs depending on your location but they go for around $400.
If you are doing some repairs or reinstalling an existing system, a permit for current system evaluation may be required and that will cost around $50.
2. Fencing Requirement
A fence may also be required by law in some regions for added safety for both humans and animals.
The fence around the lagoon should be at least 4 feet high.
The fencing cost will vary depending on the material used but on average, fencing costs anything from $8 – $46 per linear foot.
3. Site Preparation
Site preparation may be required if the property is on uneven terrain or if the soil is not suitable for a lagoon septic system.
This can add additional costs to the installation.
The type of soil on the property can also affect the cost of a lagoon septic system.
Soil that is too sandy or too dense can make it more difficult to install the system, which can add to the overall cost.
4. Maintenance Costs
Like all other septic systems, ongoing maintenance is a must to ensure the system works well without failing or polluting the environment.
The exact maintenance costs will vary depending on your location but here are some of the common costs:
- Permit renewals: Some regions will require an annual permit renewal although this requirement is mostly for larger non-residential systems. A residential permit will go for under $500 while commercial ones go for as much as $3,000.
- Discharge Testing: Discharge testing will need to be done annually. This is important to avoid pollution of the groundwater. The discharge testing will cost around $75 add or take a few.
- Electricity: The system may use a pump and that means you will incur a monthly electric charge. The exact amount will vary based on usage and applicable tariffs.
- Pumping: Like any other septic system, you need to pump the septic tank regularly. You may want to inspect the tank annually to ensure it is working properly and to determine the sludge and scum levels. Pumping the tank costs anything from $200 – $600 and you should do it every 2-3 years.
Related: Can You Put Goldfish In The Septic Lagoon?
How Does The Cost Of A Lagoon Septic System Compare To Other Types Of Septic Systems?
The most notable difference between a lagoon septic system and other types of septic systems is the use of a lagoon for secondary treatment.
In a conventional system, the effluent goes from the septic tank and into the leach field where it undergoes the final treatment as it percolates through the soil.
However, effluent in a lagoon system leaves the tank and is directed to the lagoon for further treatment.
As such, lagoon systems are ideal for sites that have poor soil conditions that wouldn’t treat effluent sufficiently in the drain field.
Another distinguishing factor is the amount of space required. Lagoon septic systems can only be installed on properties that have sufficient space.
Each region has different guidelines but as a rule of thumb, the minimum size of property that would support a lagoon system is three acres.
This may be one of the reasons why it is not a popular system for large cities.
Generally, a lagoon septic system is an advanced system and as such, it is costlier than a conventional system.
For starters, a conventional system will cost $2,000 – $7,000 while a lagoon will cost at least $2,500 and can go upwards of $15,000.
However, even though lagoon systems are more expensive than conventional ones, they are arguably the cheapest alternative systems to install.
The table below gives a clearer picture of how lagoon systems compare in cost to other systems.
| Type of system | Average Cost |
| Conventional | $4,500 |
| Lagoon | $8,000 |
| Chambered | $8,500 |
| Sand Filter | $12,500 |
| Evapotranspiration | $12,500 |
| Drip | $13,000 |
| Mound | $15,000 |
FAQs
I. How long does a lagoon septic system typically last before it needs to be replaced?
As long as the lagoon septic system is designed, installed, and maintained properly, it should last for at least 30 years.
Messing up in any of these three areas will significantly reduce the longevity of the system.
II. Can a lagoon septic system be installed on any type of property, or are there specific requirements?
The most important requirement is the size of the property. For instance, a lagoon septic system for a one-bedroom can only be installed if the house seats on a property that is at least 5800 square feet.
In addition, the soil must be suitable for a lagoon septic system and the system must be designed to handle the expected volume of wastewater.
III. Are there any environmental regulations I need to follow when installing a lagoon septic system?
Yes, the lagoon septic system must adhere to construction and permitting standards as defined by your local authority.
Depending on the location, you may need to obtain permits and undergo inspections from local health departments or environmental agencies.
It is important to consult with local authorities and hire a licensed professional to ensure that your lagoon septic system is installed properly and meets all regulatory requirements.
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