THROUGH MAY 1

There’s been good news and bad news about water lately. The bad news you know. The good news is that cryptosporidium is not some new, fatal sexually transmitted disease. (Boil your partner!) Now comes National Geographic with its blockbuster “Water” issue (November 1993) and accompanying exhibit, from which we learn, in an interactive, multimedia way, all sorts of interesting things about water: that even though the planet is more than two-thirds wet, there’s barely enough drinkable stuff to make a Slurpee; and that 11.7 gallons of water are typing these very words. Not quite as compelling as the interactive water exhibit now spewing from Washington-area taps, but still worth a visit. Mondays through Saturdays from 9 a.m.-5 p.m., Sundays from 10 a.m.-5 p.m. at the National Geographic Explorers’ Hall, 17th & M Sts. NW. FREE. (202) 857-7000. (Bill Gifford)