The federal government is poised to invest as much as $492 million to get Pure Water, the city of San Diego’s effort to turn sewage into drinking water, off the ground. Today, the U.S. Environmental Protection Agency is expected to announce that San Diego is one of a dozen applicants chosen to participate in a low-interest loan program under the Infrastructure Finance and Innovation Act. The invitation, which comes after initial vetting by the EPA, doesn’t guarantee funding but signals a very high likelihood of acceptance. Invited applicants from past years routinely obtained the funding amounts they sought.