23. How do I incorporate the transient and non-resident populations?

Transient and non-resident populations are groups of people who do not stay in the city or town all day, every day. This may include commuters, traders, students, tourists, pilgrims, etc. Information on this group is difficult to establish and you need to balance the effort used to make credible estimates with the significance of this group to the SFD as a whole.   As a first step, estimate the percentage of the total population which is transient and non-resident. Data on these populations may be available in census data, and from the tourist ministry or hotel associations.

As a rough guide it is suggested that a transient and non-resident population which makes up less than 5% of the total population can be assumed to make a negligible contribution and can be excluded. Modelling of larger transient/ non-resident populations will require estimates of their patterns of latrine usage and overall sanitation service delivery outcomes.  Remember that they may use institutional toilets in hostels or public places.  Be aware of temporal effects.  For example, if you are including the impact of an annual pilgrimage event, which takes place over two weeks, then the effective contribution of one person from this population would be 2/52 of the contribution made by someone from the permanent population. 

Where transient and non-resident populations make a significant impact at certain times, it may be useful to generate a specific SFD Graphic to examine this effect.