The construction costs of recently completed projects provide a reliable guide to the costs of similar projects in the future. Thus engineers involved in estimating the cost of a proposed ocean outfall seek information on the costs of installed outfalls. This paper provides this information for 36 outfalls on the West Coast of the U.S., three in Hawaii, and one in Puerto Rico. In addition, final cost estimates are given for seven more outfalls in California and Australia. The dimensions, characteristics, cost, and date of each outfall are presented in tables. Relationships are derived between the unit construction cost in dollars per metre of length and the inside diameter of the outfall. These relationships may be used to make an approximate estimate of the cost of constructing an ocean outfall.