Twenty-nine groundwater samples, collected from Wadi Nu'man wells, were analyzed for natural radioactivity to check for compliance with the national guideline values. Gross α and gross β screening, in addition to radon ( 222 Rn) measurements, were performed for all samples. Samples of gross activity levels exceeding the national guideline values set out for drinking water were subjected to further investigation for radium and uranium isotopes using liquid scintillation counting and α-spectrometry, respectively. The results showed that the anomalous source was natural uranium. The water contains high concentrations of 222 Rn and considerable levels of natural uranium. The 222 Rn concentration ranged from 10-100 Bq/L with an average value of about 40 Bq/L. The uranium concentration, in samples of gross activity levels exceeding the national guideline value, ranged from 9 to 55 μg/L. The levels of 226 Ra and 228 Ra were below the detection limit of the counting system in all samples. The variation in the 222 Rn and uranium concentrations was found to be linked with the local lithology. The higher values were recorded in the wells of Nu'man complex aquifer, where the predominating mineral is foliated monzonite. Recommendations and advices for water management to reduce radiation exposure to users are presented.

Socioeconomic and climatological data of the major cities of the western region of Saudi Arabia have been used to develop several models to estimate the residential water usage for different kinds of houses. The developed models correlate the residential water usages with temperature, income, family size, price of water, and availability of a garden within the house. The study shows that the residential water uses in houses supplied by a public pipe network are 1.4–2 times greater than the residential water uses in houses supplied by tankers. It also shows that the price elasticities are very similar to those estimated in the United States. Income elasticities, on the other hand, are lower than those typically found in more industrialized countries.

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