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When sizing conventional and alternative on-site sewage disposal systems for single-family dwellings, please note the following information from Snohomish Health District's policy:
To determine the total daily flow for single-family homes with:
To review the entire Interpretation of Bedroom and Daily Flow Determination Policy (PDF)
Application rates shall be determined according to soil texture type as outlined in WAC 246-272A and the Environmental Protection Agency manual.
The Minimum Land Area Requirement (WAC 246-272A) requires that minimum gross land area exists for a unit volume of sewage (450 gallons per day). Therefore, an on-site sewage disposal system application to create a new lot shall designate an area for at least a three-bedroom single-family dwelling. Note: This regulation has been in effect since July 1984.
Potential bedrooms are considered bedrooms regardless of the placement of closets, windows, and doors, or the width or location within the structure. Rooms that are considered potential bedrooms include, but are not limited to:
The Snohomish Health District typically does not count rooms such as living and dining rooms, storage areas, closets, and utility rooms as potential bedrooms.