Soap Lake is a city in Grant County, Washington, on the shores of Soap Lake. The population was 1,733 at the 2000 census. In 2002, the town announced preliminary plans to construct the world's largest lava lamp as a tourist attraction. Soap Lake apartments for rent comparison page shows most up to date rent information on Soap Lake apartments and houses. Rent information is obtained from multiple rental sources but we cannot guarantee their accuracy.