Septic systems are an effective way to handle household wastewater in areas without access to public sewer systems. For homeowners with limited space or looking to install a septic system on a budget, the size and cost of a traditional septic system can be prohibitive. This leads many homeowners to wonder – what is the smallest septic system I can buy?
In this article, we’ll discuss what features to look for in compact and affordable septic systems for small homes or properties. We’ll review some of the smallest pre-made septic tanks and systems on the market today and provide an overview of how much a basic small septic system could cost.
Page Contents
- 1 What is a Septic System?
- 2 What Are the Smallest Septic Tanks Available?
- 3 How Does Tank Size Affect System Performance?
- 4 Added Costs of Undersized Tanks
- 5 Cost to Install a Small Septic System
- 6 Save Money With a DIY Septic Installation
- 7 Can I Install My Own Septic Tank?
- 8 Is It Cheaper to Build My Own Septic Tank?
- 9 Key Considerations When Buying the Smallest Septic Tank
- 10 Conclusion
What is a Septic System?
First, let’s briefly go over what exactly a septic system is and how it works. A septic system is an onsite wastewater treatment system that uses a combination of a septic tank and a drainage field, also called a leach field or soil absorption field, to process and dispose of household wastewater.
The septic tank is a buried, water-tight container usually made of concrete, fiberglass, or polyethylene. All wastewater from your home flows into the septic tank where heavy solids settle out as sludge, while grease and lighter solids float to the top as scum. An outlet pipe at the other end of the tank allows the clarified wastewater to exit the tank and flow to the drainage field. Baffles or tees are used to prevent the sludge and scum from leaving the tank and traveling into the drainage lines.
| Septic System Component | Function |
|---|---|
| Septic Tank | Primary treatment – settles out and separates solids from liquid, retains scum and sludge |
| Outlet Baffle | Prevents floating scum from exiting the tank and clogging drainfield |
| Drainage Field | Secondary treatment – allows wastewater to infiltrate into the soil, which acts as a natural filter to remove harmful bacteria, viruses, and nutrients |
The wastewater exiting the tank is then distributed through a series of perforated pipes buried in trenches within the soil drainage field. As the clarified effluent seeps out of the pipes into the soil, additional treatment occurs as microorganisms and filtration within the soil help remove harmful bacteria and pathogens.
What Are the Smallest Septic Tanks Available?
Now that we’ve reviewed the basic components and function of a septic system, what size septic tank would work best for a smaller home or property?
Minimum Septic Tank Size Regulations
Most states and counties regulate the minimum size requirements for new septic system installations. The rules vary by location, but most recommend a minimum septic tank size of 1000 gallons. Some rural counties allow smaller tanks around 750-900 gallons for systems serving just a single-family home with 2-3 bedrooms and only one or two occupants.
It’s important to research your local regulations and acquire necessary permits before purchasing and installing a septic tank that’s smaller than 1000 gallons. Using an undersized tank can lead to system failures, backups, and costly repairs down the road.
Common Small Septic Tank Sizes
While 1000+ gallons is the recommended minimum, there are some smaller septic tanks available for tight sites. Here are some of the more common small septic tank sizes:
– 750 gallons – The smallest size permitted in some rural areas for 1-2 bedroom homes. Not ideal for full-time residences.
– 900 gallons – A marginally acceptable size for 1-3 bedrooms in rural low-use installations.
– 1000 gallons – The minimum legal size for new installations in most areas and suitable for 1-3 bedrooms.
– 1250 gallons – A better size for 2-4 bedroom homes, allows for some growth in number of occupants.
– 1500 gallons – The recommended size for 3-5 bedroom homes, optimal balance of capacity and cost.
What’s the Smallest Septic Tank I Can Buy?
Based on typical residential installation requirements and regulations, the smallest septic tank size that can reasonably serve a permanent home is 750-900 gallons. Again, these ultra-compact sizes are only approved in some rural counties for older homes or limited occupancy. They generally don’t meet standards for new construction.
The Polylok PL1000 is an example of one of the smallest commercially available septic tanks, with a capacity of 1000 gallons. This rotationally molded polyethylene septic tank measures just 92” long x 72” wide x 72” tall.
The lightweight polyethylene construction reduces installation costs, as this 1000-gallon tank weighs only 600 pounds when empty. This compact design can help homeowners on tight lots or difficult sites install a septic system that meets the minimum capacity rules for their area.
How Does Tank Size Affect System Performance?
Why are larger septic tanks typically required? How could an undersized tank affect your septic system’s function?
Insufficient Capacity
The septic tank needs to provide adequate volume and retention time for solids separation. Using too small of a tank means wastewater moves through faster, decreasing separation efficiency. More sludge and solids end up flowing out of the tank and can clog the drainage field, leading to backups or sewage surfacing on your lawn.
Reduced Anaerobic Digestion
Larger tanks promote better anaerobic digestion, which helps reduce sludge volume. In smaller tanks, sludge isn’t retained long enough for proper digestion and buildup occurs much faster. This means more frequent and costly pumping is required to remove sludge before it can overflow the tank.
Limited Emergency Storage
Smaller tanks also have less reserve capacity for temporary surges in wastewater flow. If the drainage field becomes saturated for any reason, there is an increased risk of the tank overflowing with a smaller system.
Fewer Access Points
Due to their compact size, some smaller tanks allow for only a single access point, instead of the ideal two inspection and pump ports. This can make at-home inspections, pumping, and repairs more challenging.
Added Costs of Undersized Tanks
While a smaller septic tank may seem like a money saver up front, the added costs down the road make it a false economy in the long run:
– More frequent pumping to remove excess sludge, every 1-2 years instead of 3-5. This can cost $200-$500 each time.
– Reduced lifespan of the drainage field, requiring replacement sooner due to excess solids clogging the pipes. Drainfield repairs or replacement can cost $5,000 to $30,000.
– Potential property damage, fines, and remediation costs if a failed system leads to wastewater surfacing or contaminating groundwater and wells. This can range from $10,000 to $50,000+.
Spending a little more upfront for an adequately sized septic tank of 1000+ gallons can save major headaches and expenses over the lifetime of your system. Let’s take a look at what an appropriately sized small septic system would typically cost.
Cost to Install a Small Septic System
If money is a concern, what can you expect to spend on a basic small septic system suitable for a 1-3 bedroom home? Here is an overview of typical costs for the main components:
| Component | Cost |
|---|---|
| Septic tank (1000 gal) | $900 – $2,500 installed |
| Outlet baffle/tee | $50 – $150 |
| Drainfield piping | $600 – $2,000 |
| Gravel/materials | $1,000 – $3,000 |
| Excavation & installation | $3,000 – $6,000 |
| Total basic system cost | $5,000 – $15,000+ |
As you can see, a properly sized small septic system for a 1-3 bedroom home can typically be installed for $5,000 to $15,000, with geographic location, local regulations, site conditions, and tank/field size as major cost factors.
Getting multiple quotes from reputable septic installers in your area is highly recommended. Be sure to verify the tank size and all included components and features match your needs and budget.
Save Money With a DIY Septic Installation
If you have experience with plumbing and excavation, it may be possible to save substantially on installation costs by handling a DIY septic tank and field installation. Here are some tips:
– Research local septic codes and acquire permits before starting work – this is essential!
– Rent an excavator for efficient digging of trenches and holes.
– Have a septic tank delivered to your site to avoid heavy lifting.
– Layout PVC piping and use gravel backfill for the drainage field.
– Hire a plumber for final connection of home to septic tank.
By doing portions of the work yourself, you may be able to install a complete septic system for $3,000-$7,000 in savings compared to hiring a full professional install. Only take on what you are comfortable handling safely!
Can I Install My Own Septic Tank?
Installing the buried septic tank component on your own is possible if you have advanced DIY skills and construction experience. Here are some tips:
– Research and follow all local regulations for proper siting and sizing. Get required permits.
– Rent equipment or hire a contractor to excavate the hole at proper depth and dimensions.
– Lower prefabricated septic tank carefully into hole using straps and a tractor or winch system.
– Level tank, anchor in place with approved backfill like sand or gravel. Cover top to proper grade level.
– Add inlet and outlet baffles/tees.
– Install covers to provide access to inlet, outlet, and inspection ports.
– Backfill around tank with care to avoid shifting or damage. Compact fill in layers.
– Extend inlet and outlet piping from home and drainage field using proper connections and slopes.
A precast concrete or polyethylene septic tank will be heavy, often over 1000 lbs, so lifting and moving onsite safely takes planning and the right equipment. Overall, with extensive preparations and precautions, a DIY septic tank installation is possible.
Is It Cheaper to Build My Own Septic Tank?
Some homeowners consider building a homemade septic tank from concrete or even wood to try and trim costs. However, today’s prefabricated fiberglass and plastic septic tanks are generally more affordable and reliable than site-built options.
Prefab tanks are engineered for optimal performance and structural integrity. They are available in smaller incremental sizes to provide the minimum capacity needed, while site-built tanks often end up oversized. Overall, the cost to purchase and install a pre-made rotationally-molded polyethylene or fiberglass septic tank is typically $2,000 to $4,000 less than a custom built concrete tank.
Key Considerations When Buying the Smallest Septic Tank
If you determine a compact septic system is your best option, here are some key considerations when purchasing the smallest septic tank for your property:
Check Local Regulations
Research county or state rules for minimum septic tank size and design requirements. Only consider compact tanks that meet the codes for your area.
Consider System Lifespan
Aim for a tank sized adequately for at least 20-30 years of use before needing repairs. This provides better value long-term.
Allow Room for Expansion
If there’s any chance of expanding your home in the future, invest in a tank sized for potential added capacity needs.
Have Site Evaluated
Soil conditions and space constraints should guide tank and drainage field size needs. An experienced site evaluator can help with planning.
Compare Multiple Quotes
Get 3-5 written bids from licensed septic installers to find the best combination of price, responsiveness, experience, and service.
Verify Construction Quality
Make sure any tank is certified and meets standards for watertightness, sturdy construction, and corrosion resistance. Polyethylene or fiberglass tanks often have an advantage over poured concrete.
Include Risers and Access
Having risers to bring the inlet and outlets up to grade makes inspection and pumping simpler. Access ports on both ends is ideal.
Plan for Ongoing Upkeep
Account for $250+ in annual maintenance costs for inspection and pumping of even a small 1,000 gallon tank. Proper care is crucial for longevity.
With careful planning and an adequately sized compact system, a small septic tank and field can be a smart, eco-friendly, cost-effective wastewater solution for modest rural homes and properties. Follow regulations, consider long-term performance, get professional site input, and thoroughly research products and installers. A timesaving DIY install is also an option for the ambitious do-it-yourselfer able to put in the hard work. With the right compact septic system in place, you can enjoy the benefits of an efficient, affordable wastewater treatment system for years to come.
Conclusion
In summary, while 1000 gallons is the recommended minimum tank size, smaller septic tanks from 750-900 gallons may be an option for some rural homes looking to install compact, inexpensive systems. However, the tradeoff for undersized tanks is more frequent and costly maintenance and a shorter system lifespan. With a properly sited and sized tank, even a basic home septic system for 1-3 bedrooms can be installed for $5,000-$15,000. Following all codes and getting input from experts is advised to ensure your small septic system meets wastewater treatment needs reliably for the long haul. Careful planning and maintenance will keep your system operating effectively.