COMAR 26.04.02.05. Design and Construction of Conventional On-Site Sewage Disposal Systems

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Code of Maryland Regulations › Title 26 DEPARTMENT OF THE ENVIRONMENT › Subtitle 04 REGULATION OF WATER SUPPLY, SEWAGE DISPOSAL, SOLID WASTE, AND RECYCLABLE MATERIALS › Chapter 02 Sewage Disposal and Certain Water Systems for Homes and Other Establishments in the Counties of Maryland Where a Public Sewage System Is Not Available › COMAR 26.04.02.05

This text was captured on Aug 14, 2026. It is a snapshot, not a live feed, so check the official code before relying on it.

Text

A. Sewage from bathrooms, kitchens, laundry fixtures, and other household plumbing, exclusive of the backwash from potable water treatment devices, shall receive adequate treatment from a sewage treatment unit before the effluent is discharged to an approved on-site sewage disposal area.

B. On-site sewage disposal systems and replacement areas location requirements:

(1) The sewage disposal system is at least 100 feet removed from any water well system in unconfined aquifers and 50 feet from any water well system in confined aquifers.

(2) The on-site sewage disposal system is located downgrade from a private water supply. A variance to this requirement may be granted by the Department of the Environment after consideration of hydrogeologic conditions and recommendations of the Approving Authority.

C. The owner of a restaurant or an establishment discharging grease shall install a grease interceptor on each separate kitchen waste drain.

D. Residential Septic Tank Size Criteria. Septic tanks serving a residential use, not requiring a BAT system, shall meet the following criteria and tables. This table provides for use of garbage disposal units, automatic clothes washers, and other household appliances.

Septic Tank Criteria Number of Bedrooms Minimum Septic Tank Capacity Below Outlet 3 or less 1,000 gallon 4 1,250 gallons For each additional bedroom, add 250 gallons

E. Criteria of a Residential Septic Tank.

(1) A residential septic tank shall have a minimum of two compartments or two tanks in series.

(2) A residential septic tank shall be made of materials and constructed in a manner acceptable to the Approving Authority.

(3) A residential septic tank shall be watertight. Manufacturers shall certify that septic tanks are watertight. The Approving Authority may require one of the following tests to determine watertightness.

(a) Vacuum Testing. Seal the empty tank and apply a vacuum to two inches of mercury. The tank is acceptable if 90 percent of the vacuum is held for 2 minutes.

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