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nerated by desalination also increases the cost (Al-Sahlawi, 1999).
The cost of water reuse is influenced by various factors such as treatment level, intended reuse options, location of treatment, wastewater collection and transportation. According to Qadir et al (2009), the average cost of recycling water is approximately $1.79 per cubic metre. However, compared to desalination, wastewater reuse has the advantage of cost. Fryer (2010) demonstrates that the relative marginal cost of seawater desalination is higher than water recycling, and amounts to up to $2000 per acre-foot. The water recycling represented a general fluctuation pattern between approximately $300 and $1000 per acre-foot (Fryer, 2010). Even so, water recycling appears cheaper than desalination.
5.2 Social acceptance
While both options can generate safe water, desalination seems to have higher social acceptance. Sloane (2009) investigated the acceptance of desalination and water reuse at Nourieh Palms. As shown in Table 2, in all areas but particularly drinking water, the approval rate for desalination is higher than water reuse. This reflects that more people trust the quality of water which is generated by desalination.

Table 2: Acceptance of desalination and water reuse at Nourieh Palms
Desalination (% approval) Water reuse (% approval)
Irrigation of grounds 89 76
Drinking water 81 38
Cooking water 84 43
Fountains 93 56
Cleaning 93 72
Toilet flushing 98 89
Showers 91 28
Source: Sloane (2009: 128)
For most uses, reclaimed water tends to have lower social acceptance than desalination. There are various reasons why people do not trust reclaimed water. First, most people do not understand the difference between treated and untreated water (McKenzie, 2005). Secondly, they are often concerned about the type of wastewater, treatment levels and the availability of information (Qadir, 2009). There are particular concerns with the wastewater produced by the petroleum industry, brought to the surface when drilling oil. This kind of wastewater is difficult to treat due to the high content of oil (Asatekin and Mayes, 2009). Therefore, though reclaimed water undergoes a very thorough treatment process which makes it entirely safe to drink, the public are reluctant to drink treated sewage. However, it is not impossible that people will accept drinking such treated sewage. For example, Singapore has successfully used reclaimed water, a product named NEWater, to supply drinking water (Tortajada, 2006). This reflects that treated wastewater could become widely accepted through public education.
5.3 Influence on environment
There are some environmental disadvantages of desalination. Since Saudi Arabia is rich in oil and gas, clean energy such as solar energy tends to be used less than fossil energy (Al-Sahlawi, 1999). The overuse of fossil energy may cause serious environmental pollution. For instance, oil might generate large quantities of carbon dioxide, which is the main factor leading to global warming (Al-Aza, 2005). Furthermore, the gas emissions from oil could undermine the ozone layer and cause acid rain (ibid.). In addition to environmental pollution caused by fossil energy, brine discharge is another serious problem. After desalination, the brines generally have a higher concentration of salt, nearly twice that of natural seawater (Tsiourtis