Footrests are required to lift the users' feet off the slab in case it is already fouled and also to position the users so that they are less likely to dirty the slab or the edge of the squat hole. The positions and sizes of footrests must be determined to suit the needs of the people in each area. Fig. 7.24 indicates a typical layout. Different people in different societies with different-sized bodies and varying flexibility of tendons may excrete between their feet or behind their ankles. Their feet may be parallel or angled. It is therefore advisable to check with young and old, and with male and female in a community before assuming a particular layout. McClelland & Ward (1976) reported that in one sample of 140 people, the distance from heel to anus in a squatting adult varied from 0 to 0.25 m with a mean of 0.13 m for men and 0.10 m for women.
Fig. 7.24. Possible footrest positions
Excreta enter a pit either by falling through a squat hole or by passing through a water seal. Details of seals are given later. Squat holes have to be large enough to limit fouling of the edges but not so large that children are frightened of using the latrine. The hole can either be rectangular, elliptical, pear-shaped or circular with a straight extension as in a keyhole (Fig. 7.25). The maximum width should be 180 mm and the length at least 350 mm. In a concrete slab, the edge of the former used to make the hole should be angled to ease its withdrawal after casting.
Fig. 7.25. Squat hole shapes and former (Different shapes for squat holes)
Fig. 7.25. Squat hole shapes and former (Plan)
Fig. 7.25. Squat hole shapes and former (Elevation)