A survey of 27 slow sand filtration plants in the United States indicated that most of these plants are currently serving communities of fewer than 10 000 persons, are more than 50 years old, and are effective and inexpensive to operate. A slow sand filtration research facility in Logan, Utah, was compared with the operating plants to determine if locally available, unsieved sand achieved similar results. The 75‐m3/d research facility performed well in removing turbidity, coliform bacteria, and particles of a size representative of Giardia cysts.