### Q-2, r. 22 - Regulation respecting waste water disposal systems for isolated dwellings

10. Septic tank cast on site: A reinforced-concrete septic tank cast on site must conform to the following standards:
(a)  the resistance of the concrete must be at least 20 Mpa at 28 days;
(b)  the mesh wire must be made of steel wire or rods with a minimum sectional area of 10M, spaced at 25 cm centre to centre, horizontal/vertical, grade 300 Mpa;
(b.1)  the septic tank must have the following features as to its dimension:
i.  the inside total height must be 1.5 m;
ii.  the height of the liquid must be 1.2 m;
iii.  the length must be twice the width;
(c)  the thickness of the floor and of the ceiling must be at least 15 cm;
(d)  the thickness of the concrete over the mesh wire of the floor must be at least 5 cm;
(e)  the thickness of the concrete over the mesh wire of the ceiling must be at least 10 cm;
(f)  the thickness of the walls must be at least 20 cm and the mesh wire must be placed at the centre of the walls;
(g)  the inlet pipe must be placed at such a height that its apron is 7.5 cm higher than the apron of the outlet pipe;
(h)  2 baffles, built of a material identical to the tank, must be installed vertically across the complete width of the tank, one in front of the opening of the inlet pipe, the other in front of that of the outlet pipe; however, the latter may be replaced by an effluent filter;
(i)  a partition wall must divide the tank into 2 compartments; its distance from the inlet must be ⅔ of the tank’s length;
(j)  this partition wall must be provided with openings cut across its entire width at a depth of 40 cm below the surface of the liquid and must also be provided with an opening at the bottom 2 cm in width and the height of a concrete block;
(k)  the tank must be equipped with 2 manholes, which have a minimum clearance of 50 cm;
(l)  both manholes must be equipped with lids to prevent run-off water from entering the tank;
(m)  both manholes must be extended to ground surface by means of insulated, watertight ducts equipped with watertight lids;
(n)  the outside of the tank must be covered with a bituminous coating;
(o)  the height of the backfill above the tank must not exceed 90 cm.
R.R.Q., 1981, c. Q-2, r. 8, s. 10; O.C. 786-2000, s. 14.