System Site Plans: Calculating Costs for an Installation Job Bid

It’s important to consider many aspects of system construction while developing a bid

System Site Plans: Calculating Costs for an Installation Job Bid

Interested in Systems/ATUs?

Get Systems/ATUs articles, news and videos right in your inbox! Sign up now.

Systems/ATUs + Get Alerts

After a thorough evaluation of the system, the next step in the planning process is developing a bid for the installation.

Keep in mind that you do not have to bid on every plan that you review. An installer should not bid a project if he or she does not feel comfortable with the design, owner or designer. During the review process an installer may identify factors or details related to the system that may make the system not desirable to bid. Installing the system exactly according to plan does not eliminate the installer from liability if the system has problems after construction. Several aspects of the system construction will need to be calculated to determine the cost of system installation. 

Material takeoff  

To determine the overall cost of the components and materials associated with the system, a material takeoff is developed. A material takeoff or bill of materials is simply a list of all necessary items that are needed for a job. The quantity of materials needed varies from job to job. The bill of materials generally becomes more accurate as the installer gains experience.

Some installers choose to only include the "big ticket" items in the bill of materials as they have a stock of pipes, glue, prep materials, screws and nails that can be allocated to a job depending on its size. Big-ticket items may include the septic tank, innovative and alternative components of the system treatment train (including control panels and accessories), and any chambers, stone, media, fill and cut requirements used in the soil treatment area. Installers that have a yard available for storage have the advantage of purchasing greater quantities of pipe, media or other items at a discounted bulk price and using them as needed. Other installers spend more time on the material takeoff process to estimate more accurately what the material list will be. There are several stand-alone and plug-in computer programs that may help the installer list the materials and formulate a bid for a job. 

Media (sand, crushed stone, gravel, etc.), fill (soil, loam, gravel, etc.) and cut requirements need to be calculated for the installer to quantify them in the bill of materials. Cost for transportation needs to be added to the costs of the materials for the bid offering. Cut volumes and soil that may be replaced by media or components need to be transported out of the construction site; those costs are also important and need to be included in the bid. 

Once the material takeoff is finished, the installer can identify where to purchase the items, if the items are available as prescribed in the design plans, and restock miscellaneous items if needed. Once a cost is added to the material takeoff list, the installer has a good estimate of the materials cost for a job. It is common practice for installers to add a markup to the material takeoff to cover installation costs and sometimes to cover all aspects of the installation business. This markup can be as much as 100% or more of the material takeoff in some cases when covering for all aspects of the installation. This, however, is a personal business decision. Other installers choose to calculate the actual installation costs depending on the size of the crew, equipment needed, estimated time at the site, transportation and delivery of materials and equipment, indirect costs, etc. 


Personnel and machinery time are components that greatly influence a bid. Experienced personnel are not easy to find or to keep, but experienced personnel usually require much less supervision and keep the job moving forward even during a setback or unforeseen event. The installer must weigh experience and costs when choosing a crew; the less that is spent on labor, typically the more supervision the job entails. Personnel costs can be directly included in the estimated time required to build and install an onsite wastewater treatment system. 

Site restoration

Restoration costs for improvements identified during the interview should be included in the bid. The installer can plan to do the restoration if qualified or can subcontract the work. When a subcontractor is used, the installer may mark up the costs somewhat to cover liability and coordination time. Subcontractors should understand the system installed and the importance of protecting it from damage during restoration work. 

Special equipment

The installer may need to rent or acquire special equipment in areas with high groundwater tables or steep slopes or if construction is planned during the wet season. Special equipment may include tracked equipment that can better deal with steep slopes or pumps to dewater an excavation. The installer may also need special equipment to clear land, cut trees and remove stumps. Special equipment may also include those that the installer does not use on a regular basis such as concrete mixers, asphalt layers or larger sized compactors that are needed for restoration of existing improvements. In addition, the safety plan for the specific site may require special safety equipment. Special equipment costs need to be considered in the bid. Required machinery should be included in the bid. The total time the machines spend on the site directly impacts the amount of money that machine is allocated in the bid. Acquisition costs, fuel costs, transportation, service and repair time, and replacement costs need to be included. 


Subcontractor costs are an important component of the bidding process. Electricians are typically needed, especially for innovative and alternative technologies. A good relationship with any subcontractor is desirable to avoid conflicts during scheduling or miscommunication problems that can add additional expenses to a project. Knowing the subcontractor will give the installer a good idea of how much a job can cost. Costs of all work by subcontractors need to be included in the bid. As stated above, the installer may choose to mark up these costs to cover liability on the job. 

Regulatory issues

Regulatory issues can increase costs on an installation job. Some states may require all onsite wastewater treatment systems to be approved by a central agency. However, at the county or town level there may be additional requirements such as larger tank requirements or more stringent setback requirements that may increase the costs of an installation. The installer needs to be aware of special requirements for the area where the installation is going to occur and analyze any impacts on the installation and costs for that site. 

Site-specific items

Other site-specific items that are not regulatory driven may include special homeowner requests, homeowners' association rules, or special scheduling efforts that may increase the costs or time spent on the job. During construction, depending on the site, dewatering may become an issue. Also, boulders that need to be hauled off the site or even ledge blasting and removal are other items that are specific to the site. 

Another site-specific item can be working with a new designer or a problematic designer. Sometimes personality problems put a strain on the installation and can delay construction. This should be considered when putting together the bid. Insurance costs either in general or specific to the project must also be factored in. 

With these key items quantified, the other item to consider is profit. Installation companies should all be in the business of not just covering costs but also making a good living and saving for retirement. How and when to include this in your final bid amount can vary but is as important as all the other calculations.

About the author
Sara Heger, Ph.D., is a researcher and educator in the Onsite Sewage Treatment Program in the Water Resources Center at the University of Minnesota, where she also earned her degrees in agricultural and biosystems engineering and water resource science. She presents at many local and national training events regarding the design, installation and management of septic systems and related research. Heger is the President of the National Onsite Wastewater Recycling Association and she serves on the NSF International Committee on Wastewater Treatment Systems. Ask Heger questions about septic system design, installation, maintenance and operation by sending an email to

This article is part of a series on site planning:


Comments on this site are submitted by users and are not endorsed by nor do they reflect the views or opinions of COLE Publishing, Inc. Comments are moderated before being posted.