Finally they appeared above ground today, drawn less by the relative lack of shelling than by the first running water in two weeks.

The people of West Beirut--those who live crowded in its now virtually nonexistent "safe" center--seemed to come alive for the first time since last Sunday, when Israel unleashed its first widespread attacks on the inner city.

About 130,000 refugees live hidden in the lobbies, basements, underground garages, unfinished buildings and even public gardens.

The atmosphere changed abruptly today after the Israelis turned the water back on. Judging from the pattern the last time the Israelis briefly relented on their water cutoff, the action appeared to be at least in part the result of mounting U.S. pressure.

As water flowed down streets, pouring out of mains broken by the heavy bombardment, young children frolicked, men took impromptu showers and teen-agers filled buckets and plastic cans. In some neighborhoods, the water did not reach upper floors of buildings because of lack of electricity for pumps.

In once-fashionable Sanayeh, 28 families--each with at least six members--are crowded into the marble lobby of the National Union insurance building. Yesterday, the men, women and children in that lobby were subdued, their faces vacant. The childrens' clothes were dirty. So was the marble floor. Pools of urine went unnoticed. Garbage piled up in the street outside. Flies were everywhere, crawling over men, women and children.

Today, women and young girls were busy swabbing down the marble floors. The lobby sparkled. Gone was the fetid smell that had led one despairing old woman refugee to complain the day before, "Do we have to live like animals?"

The families in the lobby have endured the past eight weeks and three days sleeping on mats, or mattresses on the floor, cooking on kerosene stoves, resigned, waiting for an end to their travail. They know that their refugee camp homes in Sabra, Shatila, Burj al Barajinah, Tariq Jdeideh are probably destroyed or so badly damaged that they will have to start life anew once the fighting stops.

"Ask anybody here what they should put on their identity cards as a profession," said a statistician who keeps careful track of the refugee population for relief agencies, "and they'll answer: 'displaced person.' "

There are all kinds of displaced persons today in West Beirut, whose prewar population of 600,000 has shrunk over the weeks to no more than 350,000 or 400,000, according to the statistician. An enormous exodus has taken place as West Beirut residents have become convinced that the Israelis are determined to try to drive them out.

The upheavals in this tormented land have lasted so long that uncovering the various layers of refugees is a task for an archeologist.

Poor Lebanese and poor Palestinians have fled here from the south since the June 6 invasion, while many other longtime residents of southern Lebanon have returned home. Palestinian families have moved constantly over the years since leaving their original homes in 1948. They arrived in Lebanon in the 1960s and 1970s, in some cases after spending time in way stations on the West Bank and in Jordan or Syria.

Other residents of Beirut's shantytown southern suburbs have joined those who arrived in the early days of this war to escape the advancing Israeli Army in the south.

Established families have fled Beirut entirely, often leaving a male relative behind to prevent squatters from taking over their homes.

One young woman has changed homes four times in little over two months--and her case is by no means isolated.

Four days before the war started, Kurds believed to be in the pay of the Syrians burned down her family house--a lovely Ottoman mansion that once belonged to the Turkish ruler of Beirut. She moved a mile away to a friend's apartment, which a week ago became too dangerous as Israeli gunners zeroed in on her neighborhood.

She moved to her sister-in-law's apartment near her family's gutted home when her brother called from East Beirut, worried about squatters. She moved again, to a room on the campus of the American University of Beirut, when Israeli gunners shelled the neighborhood and she discovered that there was no underground shelter.

She considers herself one of the lucky few. Other refugees do not fare as well.

Next to the public gardens, rescue workers were still pulling out bodies from beneath the rubble of a six-story apartment building housing an underground Palestine Liberation Organization operations room. Bombed with pinpoint accuracy Friday, the building has yielded about 70 bodies so far, and rescue workers have yet to reach the underground shelter where more than 100 residents are believed trapped and perhaps buried.

A stone's throw farther south down on Hamra, once one of the most sophisticated streets in the Middle East, life returned to a modicum of normality amid a new mood that was almost palpable.

Street vendors hawked cheap wares in front of shuttered fancy shops, pedestrians and cars picked their way through the rubble and people sipped drinks at open air cafes.

Optimists argued that the return of the water supply meant that the siege was about to end. The less sanguine feared more punishment from Israel.