A cruel tease, the commercial for HTH swimming-pool cleaner, fueling rage in steamy living rooms as the temp climbs into the upper 90s. It's an aggravating 30 seconds, with the fun-loving guy getting up from his pool-side lawn chair and jumping into the water yelling, "Canopener!"

Canopener? Are there enough people in town with dirty pools to merit this special TV campaign?

In fact, filthy pool tile is on the rise. "The metro area is adding pools at a rate of 2,000 a year," according to the National Spa & Pool Institute's Merle Dowd. Not most of us, sweating under a blanket of humidity, of course, but somebody out here has swimming-pool bacteria to consider.

Those lacking season passes to sidestroke with generous neighbors can pool their resources and sign up with a swim club or pay by the day at community pools.

For the in-town country-club feel, there are hotel memberships. Pool talk at the Washington Hilton is New Conservative/Old Money: "We have a lot of prominent members: Senator Proxmire's wife, Chuck Percy, doctors and lawyers from the community," says pool manager Colleen Corrigan. "And a lot of new members have joined the club with this administration." For $425 a year, they get pool, Jacuzzi, sauna and exercise room. The heated outdoor pool stays open until November 1, 7 a.m. to 11 p.m. daily. No splashing around just for the day, unless you check in as a hotel guest.

At the Shoreham, you'll need a cover-up to pad inside from the pool. None of that sopping wet flesh in the restaurant, thank you. Singles swin for $425, couples for $700, families for $750, pro-rated now through September 13. Quotas haven't been filled yet: There's still room to tan your body there above Rock Creek Park. Closer to downtown, the Gramercy Inn on Rhode Island Avenue offers pro-rated memberships at $75 for singles, $175 for families. "We provide towels, lockers and outlets for hair-dryers." Several local Holiday Inns offer season memberships. At the Connecticut Avenue branch (opposite the Washington Hilton) it's $190 per person, with no single-day admittance. The Key Bridge Marriott offers a combination pool-and-health spa membership of $40 per month as a special summer deal, or $450 for the year-round family rate.

Community pools are not as chic, or pricey: Fairfax residents can join the Waynewood pool in Alexandria for $350 for the family. The Bethesda-Chevy Chase Y operates the Pooks Hill Road pool at $200 for families, through Labor Day. There's a 10 percent discount for previous members. National Cathedral's Beauvoir School at 3500 Woodley Road NW is accepting members for its small outdoor pool. Fees are $290 for families, $200 for individuals.

Bannockburn Swim Club in Bethesda is not even taking names for a waiting list, but Merrimack, two blocks away, offers memberships for $180 for two heads-of-household, $120 for one, $35 for family members under 21, $55 for those 21-plus. Besides a swim team and group lessons, Merrimack offers its members an exchange with Bannockburn's bigger pool.

Last weekend at the year-old Bethesda community pool off Little Falls Parkway, a pair of extra-thin Bethesda-Chevy Chase high-school girls camped out on beach towels directly below the lifeguard they'd found cutest. Never flirting overtly, they subtly make impressions in their tiny purple and black suits. Teenage guys focused on their radios and babies took to the water in their own mini-pool with all manner of inflatables. (Early risers swim free there, 9 to 10 a.m. on weekdays). Assistant manager Tim Coleman said a good thousand people show up there on a crowded Saturday. Alice Koegel, a 19-year-old lifeguard, said, "When it's really hot it gets so packed you can't even walk on the deck."

Meanwhile, down at 21st and P, singles greased up and stretched out thigh to thigh, most never dipping in the efficiency-size rooftop pool. Gridlock occured at 1:15 Saturday when neighbors had to turn their chairs simultaneously to catch the rays. The guard's radio blared Barry Manilow while sun-worshipers read Clavell and drank Lite beer. As long as they could monitor their tans' progress toward greasy tones of perfection, the water was merely more background music for a slow burn.