Slow, gurgling sink and tub drains in an older house

Quick answer

Slow drains are usually hair or grease at the stopper and trap. Gurgling points to a partial clog or vent problem. Skip chemical cleaners on older pipes; several backed-up fixtures means a main line issue.

A sink that takes a minute to empty, a tub that gurgles after the shower turns off, a bathroom that smells slightly of sewer when the weather warms up. These are some of the most common calls we get from San Gabriel homeowners, especially in houses built in the first half of the twentieth century.

Older homes have drain systems that have been modified, extended and repaired over many decades, and small problems in them tend to look alike.

This guide explains what slow and gurgling drains usually mean, what you can clear safely, and what we do on a visit.

How a household drain works

Under every sink and tub there is a trap, a U-shaped bend of pipe that holds a little water. That water blocks sewer gas from coming into the room. From the trap, the drain runs to larger pipes that carry waste out to the sewer, and a system of vent pipes lets air into the drains so water flows freely without sucking traps dry.

When any part of that system is partly blocked or poorly vented, you notice it at the fixture.

What slow drains usually mean

Hair and soap scum are the usual culprits in bathroom sinks and tubs. They build up on the stopper linkage and in the trap.

Grease and food collect in kitchen drains, especially beyond the trap where the pipe runs horizontally.

Old pipe materials. Many older homes still have galvanized steel or cast iron drain lines in places. Galvanized drain pipe narrows on the inside as it corrodes, catching debris, and cast iron can develop rough interior surfaces over the decades.

Old pop-up stoppers. In a lot of older bathroom sinks, the stopper and its pivot rod are corroded and catch hair.

What gurgling usually means

Gurgling happens when air is pulled through a trap because the drain cannot get air from its vent. It can come from a partial clog farther down the line, a blocked roof vent, or a fixture added during a remodel without adequate venting. Gurgling in one fixture when another drains, for example a tub gurgling when the toilet flushes, points to a shared line that is restricted.

A sewer smell in a room is often a trap that has dried out, especially in a guest bath that is rarely used. Run water in it for a minute and see if the smell goes away.

What you can safely do

• Pull the sink stopper and clean off hair and gunk. Many lift straight out or come out after loosening a nut on the pivot rod under the sink.
• Use a plastic drain cleaning strip, the kind with barbs, to pull hair from sink and tub drains.
• Use a cup plunger on sinks and tubs, covering the overflow hole with a wet cloth so the plunger has suction.
• Run hot water after using the kitchen sink and keep grease out of the drain.
• Run water in seldom-used fixtures every couple of weeks to keep traps full.

When to call us

• A drain that is still slow after cleaning the stopper and plunging
• A trap or drain connection under the sink that leaks
• Corroded traps or tailpieces, or a pop-up assembly that is falling apart
• Gurgling at one fixture, or a smell that does not go away
• A disposal that hums or drains poorly

If several fixtures back up at once, or water comes up in the tub when you run the washing machine or flush, that is a main line problem, and a plumber with a camera and a sewer machine is the right call.

What our drain visit involves

At the sink, we remove and clean the trap and inspect the tailpiece, slip nuts and washers. Corroded or cracked parts are replaced, usually with new traps and tailpieces sized to your fixture. We clean or replace the pop-up stopper, and if the old one is beyond repair, we can install a new drain assembly.

For clogs past the trap, we use a hand auger to clear the branch line toward the wall. In tubs, we pull the overflow plate and clean the stopper mechanism, then clear the line.

We reassemble everything, run water at full flow, and check every joint for leaks. We will also point out anything we see that suggests the drain system needs more attention down the line, such as heavy corrosion on the pipe coming out of the wall.

Our minor plumbing repairs page lists what we handle.

The sink cabinet

Slow leaks at a trap often go unnoticed until the cabinet floor swells or the cabinet smells musty. After we fix the drain, we can repair or replace a water-damaged cabinet floor; see door and cabinet repair.

Tubs with old drain hardware

Many older San Gabriel bathrooms still have their original cast iron tubs, and those tubs often have drain and overflow fittings that have been painted, plated and patched over the years. The trip lever on the overflow plate may be seized, the stopper linkage behind it may be corroded, and the drain shoe under the tub may be weeping at its gasket.

We can usually replace the visible stopper, trip lever and overflow plate from inside the tub. Work on the drain shoe underneath depends on access, which in older houses is sometimes through a small panel in a closet or hallway behind the tub.

Text a short video of the drain and a photo under the sink to (626) 684-3505, and we will tell you what we think is going on.

If a drain call on the west side of town runs past noon, Newport Seafood is our usual stop on any day except Tuesday.

Want us to handle it?

Call or text (626) 684-3505, Mon–Sat 8:30 AM–7 PM. Send a photo and we will give you an upfront quote.

Call or text (626) 684-3505