mounds for septic systems in Bellevure, King County, WA

A mound septic system in Bellevue, WA, has many advantages. It is easy to use and treats wastewater well. However, there’s still more than meets the eye. This blog will cover what a mound septic is. It will also explain its usability and the disadvantages it might pose for your property.

An overview of mound septic systems

A mound septic system is a drain field that sits above a natural soil surface in an engineered mound

This engineered mound conceals a network of small-diameter pipes. Septic tank effluent is pumped into the network in controlled doses. This ensures uniform distribution throughout the bed. The pumped effluent then leaves the pipes under low pressure. It drips downward through small diameter holes in the gravel and sand. 

mounds for septic systems in Bellevure, King County, WA

Image Source:

When are they used?

A mound septic is an alternative septic system. It is used when a property has shallow soil depth, high groundwater, or shallow bedrock. Or if a property has limited access to multi-stage wastewater treatment systems. 

What are their disadvantages?

Before installing a mound septic system in Bellevue, WA, learn about its disadvantages for you and your property.

Impact on landscaping

Mounds are not a thing of beauty. Well, they do look gnarly and gigantic. 

A typical mound size is 34 ft by 93 ft, and its shapes vary with design. These alternative septic systems are measured according to the amount of waste they treat. Typically, septic designers calculate this based on the number of bedrooms in the home. So, the more rooms in your property, the larger your mound is.

However, you can avoid looking at gnarly sights daily. You can always opt to landscape your mound. There are many ways to creatively and stealthily “cover” the mound. You can hire a professional landscaper or venture on a DIY landscape project. 

Space requirements 

As mentioned in the section above, septic mounds need enormous space for installation. Mound septic systems are long and narrow and have plenty of contours. Depending on soil and site conditions, the mound can be as long as 200 feet for a 3-bedroom house. A mound system adds up to 30 feet in length per bedroom for larger properties.

The larger the house and the more bedrooms there are in a property, the larger the space required to install your septic mound. 

Higher installation costs

The cost of installing a mound system is higher than that of conventional systems. The system is used in areas with high bedrock or water tables. As a result, it will need extra construction materials, septic tank components, and professional fees for installers.

You also have to consider the pre-installation expenses, such as soil tests and PERC tests. You’ll also need licensed engineers or septic system designers to design your system. You’ll need to get your requirements approved by the Health Department in King County.

Maintenance and repair challenges

The main challenge when it comes to mound systems is their stability. If the mound is installed incorrectly or not stabilized by the installers, soil erosion follows. If erosion in the soil occurs, it will expose and compromise the drain field

If this happens, it becomes a domino chain of health hazards. The system cannot drain. This can cause back-ups in your home and environmental hazards. For example, possible groundwater contamination is caused by wastewater pooling in the ground. 

Aside from the health hazard risk, erosion can burn a hole through your wallet. Repairing a compromised or failed mound septic system can cost thousands of dollars.

Hence, proactive maintenance is greatly encouraged. Property owners should proactively do routine maintenance. This includes pumping the tank, cleaning or replacing the filter, regularly inspecting the pump, and installing a high water alarm. This ensures all flows into the mound system.

Fresh N Clean Septic is your professional go-to for septic services in Bellevue, WA

We prioritize your mound’s optimal performance. Our septic professionals are accurate and eco-friendly. We guarantee top-notch service to preserve functionality, stability, and performance at its best peak.  

Energy consumption for pumping

Many people may ask if a septic pump uses much electricity. The short answer is no. A few people believe that septic pumps use electricity – this is not the case. A typical septic pump uses about 10 kWh of power per month, less than other devices in your home. However, the wattage of the pump can differ based on the specific model and manufacturer.

The challenge with an electric pump is during power outages. Pumps need at least 48 to 72 hours to sustain operations. To avoid mishaps with your septic pump, you can install a small solar generator. It maintains and powers your pump during power outages.


Septic mound systems keep waste water away from the water table. Installing a mound septic system in Bellevue, WA, can better protect the water table than other septic tank measures. 

However, these septic systems are great if your property has a shallow soil depth, high groundwater, or a shallow bedrock area. 

Find a licensed engineer or septic systems designer to ensure that a septic mound is the best system for your property. 

Frequently asked questions

How will property owners know if they need a mound septic system?

A licensed engineer or a certified septic designer is the sole authority in determining which type of septic system suits your property.

Do mound systems have to be pumped?

Yes, mound systems must regularly pump waste out of the septic tank.

How often should we pump a mound system?

Pumping a mound system would depend on the age of your system and frequency of usage, but a standard practice encourages homeowners to have their mound systems pumped yearly. 

Leave a Reply