PART 8 — SEWAGE SYSTEMSUpdated for the 2024 Ontario Building Code
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8.7.5.3.Construction Requirements
(1) Sentences 8.7.4.2.(1), (2) and (4) to (11) apply to the construction of a filter bed.
(2) The lines of distribution pipes or leaching chambers shall be evenly spaced over the surface of the filter medium to
which the sanitary sewage is applied, with the outer most distribution pipe or leaching chamber not more than 600 mm
from the perimeter of that area with a maximum spacing between the centre lines of the distribution pipes or leaching
chambers in accordance with Table 8.7.5.3.
(3) The filter medium shall have a minimum depth of 750 mm below the stone layer or bottom of the leaching
chambers and shall be clean sand comprised of particles ranging in size between the limits of,
(a) an effective size of 0.25 mm with a uniformity coefficient not less than 3.5,
(b) an effective size of 2.5 mm with a uniformity coefficient not greater than 1.5, and
(c) having a uniformity coefficient not greater than 4.5.
Table 8.7.5.3.
Maximum Spacing Between Centre Lines of Distribution Pipes or Leaching Chambers
Forming Part of Sentence 8.7.5.3.(2)
Distribution Method Maximum Spacing Between Centre Lines, mm
Distribution pipes 1 200
Type I leaching chambers 900
Type II leaching chambers 1 000
(4) The filter medium shall be unsaturated for its entire depth.
(5) Where there is more than one filter bed in a leaching bed, the filter beds shall be separated by at least 5 m between
the distribution pipes or leaching chambers of the filter beds.
(6) The base of the filter medium shall extend to a thickness of at least 250 mm over an area meeting the requirements
of the following formula:
A = QT/850
where,
A = the area of contact in square metres between the base of the filter medium and the underlying soil,
Q = the total daily design sanitary sewage flow in litres, and
T = the lesser of 50 and the percolation time of the underlying soil.
(See Note A-8.7.5.3.(6) and (7))
(7) The stone layer or bottom of the leaching chambers shall be not less than 900 mm above the high ground water
table, rock or soil with a percolation time of more than 50 min. (See Note A-8.7.5.3.(6) and (7))
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
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Code text is reproduced for reference from the Ontario Building Code (O. Reg. 163/24, 2024 Building Code Compendium). This page is provided for general information and is not an official copy. Always verify requirements against the official Ontario Building Code and confirm with your local building department.