3.2. Estimation of water and energy demand
To estimate the water demand for limited domestic use purposes, the energy demand for a water
treatment system, size of the water treatment system, and the availability of solar energy under limited
conditions, the following methodology was used. The minimum water demand per person for limited
domestic use can be considered as 25 liter/person/day [10]. The average household size of Pathumthani
province is 4 persons for non-municipal areas [11]. Using equation (1) the minimum water demand for
the suitable area was derived.