Install Septic Tank System Cost

How much does it cost to build a septic tank system?

Though many homeowners are tempted to find ways of saving money and doing a lot of large-scale projects on a DIY basis, the installation of a septic tank system must be undertaken by a professional contractor. Why? It involves the removal of biodegradable or organic wastes to a place that is secure and suitable for the natural breakdown process to occur. Should this system have any flaws or failures the financial costs of repair or remediation could be catastrophic.

For the purpose of this discussion we will consider the costs and materials associated with the building of a traditional, single-family home, septic tank system using the gravity design. According to the "standard or conventional gravity system for a three bedroom house on a level site in good soil can vary greatly depending on where you live but it should be roughly between $1,500 to $4,000..."

All systems are composed of two fundamental fixtures - the tank and the "leachfield" or the drain field. These will require several basic components in order to function properly, but they also must be designed to work with the number of bedrooms in the home, the layout of the site, and the texture of the soil that will hold the system.

Cost breakdown

The standard system will include:

  • Tank - can be made of concrete, fiberglass or polyethylene and come in a range of sizes. Most homeowners will opt for the larger, 1,250 gallon tanks because they tend to run only $100 more in price than a 1,000 gallon unit. The most common choice of material is concrete and these will cost around $500 to $800 depending upon size and installer;
  • Drain gravel - the amount of gravel required will vary by the soil type of the site and the overall landscape, the average costs for a single ton of clean drain gravel is going to be between $9 and $12;
  • Vaults - these are also made from different materials, but most modern homeowners opt for the plastic varieties. These, according to will come at a cost of $85 per four foot section (installed);
  • Piping - this will vary according to the size and design of the system; and
  • Labor and design - a qualified engineer and septic contractor will be needed in order to get the necessary health and sanitary permits, appropriate excavation at the site, and permission/approval from local building or planning agencies. There are also soil tests that must be done before any septic is officially approved for use. Costs can vary dramatically on all of these items, depending upon the complexity of the system or the site. Generally, however, the permitting process should not exceed $1,000 in fees, design and installation should not range far beyond the $1,500 to $4,000 indicated at the opening of this discussion, and inspections by local authorities should come at no additional costs (with the exception of fees for soil testing).

Additional considerations and costs

Like all major home projects, the installation (or replacement) of a septic system should follow a pattern of seeking several bids from qualified professionals. The National Onsite Wastewater Recycling Association is a good resource for identifying experienced and licensed professionals in any area, but a call to the local sanitation office can also provide a few contacts for the project too. It is important to require references and proof of adequate insurance for a project such as this, and the work and materials should also have some sort of guarantee or warranty as well. Often an installer can even provide some sort of maintenance agreement that will see the system pumped every one to three years, and inspected annually.

Typical costs

$4,000 - $14,000
Medium: $4,000 - $14,000
High: $25,000

Cost to build a septic tank system varies greatly by region (and even by zipcode). Get free estimates from septic tank specialists in your city.