FOR THE weekend repair guy, what you know can be more frightening than what you don't. Take, for example, my recent encounters with the single-lever faucet in the kitchen sink. It dripped, repeatedly. I attempted to fix it, repeatedly.

I knew how the faucet was put together. I knew where the trove of replacement parts had been stashed in the basement. Yet as I began my journey through its innards, familiar feelings of dread, the "what-ifs," washed over me.

What if the new parts did not fit in the old fixture? What if the rotating ball in the faucet refused to rotate? What if not only the kitchen sink but the entire house plumbing system ended up being put out of commission until the faucet was fixed?

I knew about these worst-case scenarios because, at one time or another, they had happened to me. The kitchen faucet, like so many other components of an old house, had a history. It began on a Thanksgiving weekend many years ago. That was when I cajoled the plumber, who was there to install a new water heater, to also install this kitchen faucet. In the process he removed the shutoff valve under the kitchen sink.

Somehow I knew this shortcut was going to come back to haunt me. But at the time I was so grateful that the guy was on the premises, dealing with our plumbing emergency, that I didn't care. As plumbing emergencies go, it was a good one. On the Friday night after Thanksgiving, with my house crammed with visiting relatives, the water heater died. I hurried to the basement, spotted a puddle on the floor and for a brief moment entertained the hope that the puddle had been put there by my visiting, diaper-wearing nephew. Sadly, I surmised that the water had come not from the kid, but from the bottom of the water heater.

Nowadays, as a veteran home owner, I have a well-established relationship with a plumber. Not only do I see my plumber often, I know where he plays golf, where he goes fishing, where his wife works and what night his assistant sings karaoke. But back then, I was new in town and in a major panic. I phoned until I found a department store that promised to send out a water heater and a guy who had dealt with the store, a rent-a-plumber, who would install it the following day, a Saturday. While the rent-a-plumber was hooking up the new water heater, I asked if he could stop the kitchen faucet from dripping. He put a wrench to it, but announced that the old faucet needed to be replaced. Before he could put away his tools, I had hurried out to one of the few plumbing supply stores that was then open late on Saturday afternoon - the Schumacher & Seiler on Harford Road (now it closes at noon on Saturday). I fetched a replacement faucet and presented it to the rent-a-plumber.

Installing a faucet is a mean job. You have to position yourself underneath the sink and work upside down and backward and, in this case, navigate through a maze of pipes. To simplify the proceedings and get a straight shot at the underside of the faucet assembly, this guy sawed off the shutoff valve.

As the name implies, this device controls the supply of water to a sink, a toilet or any other fixture that draws water. I am very fond of shutoff valves, as are most weekend repair guys. The beauty of this device is that it lets you isolate your plumbing problems and put off fixing them. You simply cut off the water supply to the broken fixture and put your feet up until you are motivated to repair the trouble.

However, if you are faced with a broken plumbing fixture that doesn't have a shutoff valve, the only way you fix it is to turn off the main water supply. That means the water works of the household - showers, dishwashers, washing machines and toilets - remain dry until you are finished with your repair. It is like working without a safety net.

Dire thoughts rushed through my mind this week as I turned off the main water supply, then bled the cold water system, watching water flow out of the broken kitchen faucet, the low point in the household's piping, like soda from an overturned bottle.

I peeled off parts of the faucet until I got down to the two springs covered with rubber rings that sat at the bottom of a bowl-shaped assembly. These springs and rings, reacting to pressure from the lever handle, control the flow of hot and cold water. When they wear out, the faucet drips. First, I replaced just the rubber rings. The faucet still dripped. Next, I replaced the springs, using the tip of a pencil to maneuver the tiny parts into place. The drip stopped.

So as another Thanksgiving approached, the storied kitchen faucet is functioning again. The old water heater is also working, even though it occasionally makes strange noises. If you live in a house long enough, you begin to calculate the age of your appliances and fixtures by matching them with ages of your kids and kinfolk.

For instance, when that water heater and faucet arrived in our house, my diaper-clad nephew was about 2 years old. Now he is about to enter high school. I figure the water heater and that recently repaired kitchen faucet should last until the nephew is ready to go to college.