PLUMBING : A Clear Route to Clog-Free Drains : Underneath it all, pipes aren’t so tricky. When trouble comes, take the plunge.

It’s the forgotten area of your home’s plumbing system. Forgotten, that is, until it fails; then it becomes the cause of many headaches, until the problem is fixed and you can go on forgetting it again.

The drain system is the result of thousands of years of experimentation in removing waste water from a home.

Ancient Roman noblemen had the most efficient and trouble-free drains ever devised, but they weren’t what we’d call “environmentally friendly.” Homes were built next to brooks, and waste water was channeled downstream into the water that lesser citizens drank.

Over the centuries, there were many inventions to get rid of waste water, including pipes that took it from the house to a common sewer. But the same putrid problem usually occurred--gas created by the decomposing waste in the sewer would flow freely from the drain into the house.

Around 1850, an ingenious London plumber devised the S-trap, which meant bending the drain from the sink into an “S.” When water ran down the sink, it flowed through to the sewer drain. When the faucet was turned off, enough water remained at the bottom of the S to block sewer gas from backing up through the sink.

However, sometimes water flowing through the drain completely siphoned out, leaving the S empty and requiring a maid (because this was state-of-the-art plumbing, it was the wealthy who first had it installed) to pour a little water down the sinks after they were used to make sure the traps were filled.

Finally, near the end of the 19th Century, plumbers figured out that a venting pipe running from the drain to the roof equalized air pressure throughout the system and prevented siphoning from occurring.

The more efficient P-trap took shape in the early 1900s, and your drain hasn’t changed much since.

Waste water flows freely to the sewer; water in the P seals off sewer gas, and the same sludge and muck in your grandparents’ drains is clogging up yours today.

“Debris accumulates on the inner walls of the drain pipe, especially in older homes that have cast-iron drains,” says Ted Blanke of Central Plumbing & Heating Supply in La Mirada.

“Drains from the laundry are filled with the crusty residue of detergents, and from the kitchen you get grease and food debris. Where these two meet on their way to the sewer, you can have clogging.”

Homes that have been vacant for extended periods often have drain problems. “The debris on the inside of the drain dries out; then, when someone comes in and pours water down the sink, it causes the debris to flake off,” Blanke says.

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Most homes built since the ‘70s have drain systems made of plastic or PVC. Although there’s never a problem with rust buildup in these systems, they’re still vulnerable to sludge buildup that slowly closes the diameter of the pipe. Until one morning you take a shower and find you’ve got a bath.

The first course of action when you’ve got a plugged up drain? Pull out the handy old plunger.

“If the clog is close to the trap, plunging it out can be effective,” says Bill Greenwall of Greenwall Plumbing in San Clemente.

Fill the basin with a little water; seal off the overflow holes near the top of the sink with your hand or a wet washcloth, and pump away. After a minute or two, stop pumping and check to see if the drain is flowing. If not, go another minute.

“You’re not doing any damage by using a plunger, so you could keep going until you get tired or the sink is unclogged,” says plumber Randy Wilson of Santa Ana. “But if it’s just not working, you may have to move on to other methods.”

Drain cleaners can be hit-or-miss. “You might find they work one day and not the next. It depends on the clog and the condition of the drain,” Wilson says. “They’re worth a try if plunging doesn’t do the trick, but if the drain is still plugged up, it’s time to try something else.”

Lots of people are afraid of snakes, but the plumber’s variety is probably the most effective way to break through a clog. Hand snakes, available at hardware stores for $5 to $10, are made of coiled metal, are 10 to 15 feet long and are designed to clear clogs that have occurred beyond the trap.

To use it, push the end of the snake down the sink or toilet or down the clean-out, which is a plug that screws into the drain under the sink or on the other side of the wall. By turning the adjustable handle, you can get around bends in the drain system and eventually hit and break through the problem.

A relatively new alternative to the hand snake is the balloon valve. It is attached to the garden hose; push the hose down the clean-out and turn the water on. A constrictor at the end of the valve forces water out at a high pressure and also makes the rubber body of the valve balloon up and seal off the drain. The water pressure eventually becomes so great that the clog is forced through.

However, there is a danger in working with these devices.

“The problem with putting this or even just your garden hose without an attachment down your drain is that it can get stuck,” Blanke says. “If you’re going to put a hose down a clean-out, I’d suggest cutting off the head, which would help keep it from getting stuck in a bend of a pipe. I’ve seen drains that had to be dug up in order to remove items that had been inserted to clear them.”

There are occasions when the hand snake or balloon valve can’t reach or punch through a blockage. Electric snakes that range from 30 to 50 feet long are available at most rental yards for $5 to $10 per hour or $30 per day. An electric motor keeps the coil moving and makes it surge toward the clog.

If you’ve tried all of these methods and the drain still isn’t running freely, it might be time to call in the artillery. Plumbers have longer, more powerful snakes that can break through most anything in their path.

Unusual or repeated clogging may require a plumber to use a technique more common as a hospital procedure. “There is video equipment available that is sent down the drain and which sends back a picture of the problem,” Blanke says.

When drains throughout the house are slow, and the front yard has a large tree or two, the suspicion is often root damage to the waste line.

“Many homes have a waste line going to the sewer that’s made of clay,” Blanke says. “Once the cement that’s used to connect the line dries out, tiny roots can break the seals, grow and create an obstruction in the line.”

In that circumstance, a special snake with a cutting edge is sent down to clear away root growth. Many homeowners find it necessary to have their waste line treated this way regularly. Once they notice the drains slowing up, a plumber is called to cut away the roots.

“It’s fine to have this done occasionally, but if you have to have it done every three months, it’s probably cheaper in the long run to go in and fix the pipe,” Wilson says.

Using electronic homing gear, plumbers can zero in on root growth so they don’t have to dig up half the front yard. Once digging starts to fix a drain problem, it gets to be expensive. A simple replacement of part of a waste line can cost $1,500, not including the new landscaping that will be needed.

“A lot of people think that if the obstruction is beyond the curb, past their property line, it’s the city’s responsibility,” Blanke says. “However, the homeowner is responsible for the waste line all the way to the sewer, which is under the street. If there’s an obstruction near the sewer line, you have to add the expense of digging through the asphalt and restoring it.”

While your drainage system is nearly maintenance-free, there are a few things you can do to help keep it operating efficiently:

* If one drain tends to clog more easily than others, consider a screen. “This would be a good idea if a bathroom sink or tub tends to get a lot of hair,” Wilson says. “Shampoo and toothpaste tube caps that fall down an open drain can also cause problems.”

* Periodically run water down all drains. “A lot of wet-bar sinks don’t get used very often, and people suddenly find there’s a horrible smell coming from that unused sink. The water in the trap has evaporated, and the seal is broken,” Wilson says.

* Be especially careful about the sinks and basins where most of the clogging materials are generated. Laundry tubs are notorious for the amount of lint that go down their drains. Kitchen sinks need special care because of the grease they have to channel.

“After you use your disposal, let some hot water run through the drain,” Greenwall says.