A survey of the orientations of domestic solar water heaters in Malaysia showed a wide range of variations. These collectors are installed on the roof, the slope being the same as the slope of the roof, with the result that the common slopes found are between 30 degrees and 40 degrees. Also, the collectors' azimuth angles are the same as the azimuth angles of the roofs. These are facing in every direction: north, south, east, west, northeast, northwest, etc. A computer program is developed to study the effect of orientation of the collector on the annual energy received. It is observed that most collectors in Malaysia are incorrectly installed and they are receiving 10-35% less radiation than a properly installed collector, while in some extreme cases, they are receiving as little as 50%.