Pressure distribution systems are allowed on any site that is suitable for a conventional private sewage-disposal system. There must be at least 6 inches from the original grade to the top of the distribution piping. What is the required minimum depth from original grade? You will have to check your local code requirements. The data should be available to you, probably in tabular form. In general, the depth ranges from 49 to 53 inches.

The estimated daily wastewater flow and the design loading rate based on the perk rate for a site are used to determine the required size of the absorption area. Once again, data in your local code requirements will help you to define a proper size. Normally, you will need an absorption area that equals the wastewater flow divided by the design loading rate that is provided in your local code. The design load factor depends on the perk rate. For example, my local code says that a perk rate of 10 to less than 30 minutes will give me a load factor of 0.8. Since local jurisdictions adopt a code and have the right to alter it, so you must check your current codes to ensure that you remain in compliance.

A rule-of-thumb for computing wastewater flow is to consider that a residence will use 150 gallons per bedroom per day. You can find more data of this type in your local codebook.