Sand Filter Septic System
A sand filter septic system is an advanced wastewater treatment option that uses a large sand pit to filter effluent before it reaches the drainfield. This system adds an extra layer of protection beyond a standard septic design, helping ensure cleaner, safer wastewater dispersal.
Sand Filter Septic Systems at McNair Septic
A sand filter system is like a pressure distribution system, but it incorporates a large sand pit for filtration between the pump chamber and the drainfield. This system consists of a septic tank, a pump chamber, a sand filter and a drainfield (AKA leech field). The pump chamber can be incorporated into the septic tank, but is more commonly found in its own second tank. The septic tank must be placed accordingly so that it is downhill from the home/building’s plumbing. A biomicrobial process in the septic tank treats the waste before it reaches the pump chamber. Further settling occurs in the pump chamber, ensuring that the pump does not send solid material to the drainfield. The pump chamber contains two floats: an on/off float (lower) and a high-water alarm float (higher). When the effluent in the pump chamber reaches the on/off float, the pump turns on and doses a set amount of effluent to the sand filter. There, a valve box evenly distributes the effluent between pressurized lateral lines in the sand filter. The system must use a pump even if gravity flow can be achieved from the pump chamber to the sand filter.
This is to ensure that the sand filter lines are pressurized and all parts receive the same amount of effluent. Each lateral line has orifices that allow the effluent to reach the sand throughout the entire filter at the same rate. The effluent then filters through the sand where another bio-microbial process treats the effluent. After filtration, the effluent is collected at the bottom of the filter and funneled into a pump chamber. This pump chamber also contains two floats: an on/off float (lower) and a high-water alarm float (higher). When the effluent in the pump chamber reaches the on/off float, the pump turns on and doses a set amount of effluent to the drainfield. The effluent is then dispersed by a distribution box into several lateral lines where it is filtered through the soil. By the time the effluent has filtered through the soil and reached the water table, it is clean.
If the water level in the first pump chamber ever reaches the high-water alarm float, the alarm will go off, indicating that there is something wrong with the system.
If the water level in the second pump chamber (in the sand filter) ever reaches the highwater alarm float, the alarm will go off AND the pump in the first pump chamber will automatically be turned off to prevent the sand filter from over-flowing.
Sand filter systems should have an operation and maintenance inspection done once every year of operation. Concurring reports may need to be turned in to the county.
Septic systems are sized according to the amount of waste they will be treating, usually estimated by the number of bedrooms in the home. For non-residential buildings, water usage usually determines the size.
The most basic sand filters are rectangles, usually 12 feet wide and between 25 and 35 feet long. The most basic drainfields include parallel, 60-foot-long lateral lines that are spaced six to eight feet on center. More intricately designed drainfields may include lateral lines of varying lengths (from 36 to 60 feet) that branch out from the distribution box in multiple directions.
Upon installation, the only parts of the system that will be visible from above ground are 24-inch riser lids above the tanks and sand filter, valve box lids at the sand filter and the drainfield, and observation port lids at the ends of the lateral lines in both the sand filter and the drainfield. Each of these lids will be flush with the final grade and can be walked on, mowed over or disguised to lessen noticeability.
Sand filters and drainfields should be treated as fragile to increase their longevity. Large animals such as cows or horses should not be kept on sand filters or drainfields and vehicles should not be driven over them. Vegetation with intrusive roots should not be planted near them. Finally, a home owner should be mindful of what is going into the system.
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FAQs About Sand Filter Septic Systems
What makes a sand filter system different from other septic systems?
A sand filter system includes a sand pit between the pump chamber and drainfield, which provides an additional bio-microbial treatment step. This makes it more effective than simpler systems when extra filtration is needed.
How does wastewater move through a sand filter system?
Wastewater flows from the septic tank into a pump chamber, where it’s dosed to the sand filter through pressurized lateral lines. After filtering through the sand, the effluent enters a second pump chamber before being sent to the drainfield.
What maintenance does a sand filter system require?
Sand filter systems should have an operation and maintenance inspection once every year. Counties may also require inspection reports to be filed.
How large is a typical sand filter?
Most sand filters are rectangular, about 12 feet wide and 25–35 feet long. Drainfields are typically made up of parallel lateral lines 60 feet long, spaced 6–8 feet apart.
Can sand filter systems be installed on any property?
They’re often used where standard systems aren’t suitable, such as in areas with poor soil or high groundwater. A professional site and soil evaluation is required to determine suitability.
The Process
Planning
All we need is your parcel number or address to begin. We research your property in advance, gather details about your future plans, and may schedule a site visit or call. Any questions are addressed quickly to keep the process moving.
Soils Evaluation
Most projects start with a soil evaluation (perc test), the first step toward system approval. We handle everything—from digging and testing to county applications, fees, and paperwork—while keeping you updated every step of the way.
On-Site Septic System Design
After completing the soil evaluation, we quickly create a detailed, cost-effective septic design, typically within one to two weeks, that includes all calculations, maps, and specifications, while handling every detail of the submittal process for you.
Review and Permitting
Most counties allow up to three weeks to review septic designs and soil evaluations, though some return them sooner. Once approved, we’ll send you a copy and can also forward it to licensed installers so you can receive system bids.
Taking Care of You
We handle everything—even the required county as-built map—so your septic system is approved and recorded. With no complex contracts, we start right away and keep things moving. Consultations are always free, so call us anytime.
Support
We can assist you in finding reputable septic installation and maintenance companies that can service and maintain your new system.
