Up until around 1950, almost every bathtub had something called a drum trap installed beneath it. A drum trap is different than the typical P-trap that is seen under most fixtures today. The modern P-trap is named that because if you turn it on its side, it is shaped like the letter “P”. Drum traps are shaped like a drum and are about the size and shape of a two-pound coffee can.

Drum traps, like any other trap, are designed to hold water in them. The water in the trap makes a seal and the seal prevents sewer gases from escaping into the house. In the early days, people were worried about the water evaporating out of the trap so the larger drum-shaped traps were installed. They held more water and had a larger water surface area so the water would be less likely to evaporate.

Antiquated drum traps are commonly the reasons for plugged tub drains that need to be unplugged. If a power snake is used to unplug it, a problem arises when the snake hits the area where the drum trap is located and the pipes do not match up on both ends of the drum. The snake has nowhere to go. Also, if it is a lead drum trap, there is a chance of the power snake piercing the side of the lead drum trap.

Drum traps also tend to be difficult to take apart to clean out. Some of them come with a removable cover on either bottom or the top. Over time that cover gets corroded shut and welded into place. Often, in the process of trying to get that cover off it takes so much force that it twists the whole lead drum trap into a mess. St Paul Pipeworks plumbers recommend replacing existing drum traps with a more modern P-trap. The P-traps are designed to be easily taken apart so if it ever does plug up, access isn’t hard to clean it out.

St Paul Pipeworks plumbers replace drum traps so often, they always have the right materials stocked on their trucks. They have learned the common layouts that work to allow them to take out the old drum trap and get the new P-trap installed. It can be a bit tricky because there are often floor joists and other structural lumber in the way.

St Paul Pipeworks plumbers are used to working around existing structures when taking the whole lead assembly out. They go all the way back to the cast iron or galvanized steel pipe that the lead trap fastens to and make a cut where the lead ends. Then the plumber makes a transition to the new, heavy plastic ABS pipe and runs that pipe over to the bathtub installing the new P-trap in place.

Along the way in the section between the old pipe to the bathtub waste, typically there is also a vent pipe for the sewer gases to escape. It also needs to be joined to provide air to the whole system. Upon completion, the plumber will thoroughly test the trap to ensure all clogs are resolved and the new P-trap will drain much better than before.

If you are having trouble with a plugged-up bathtub drain or are just looking for a quality plumber in the St. Paul and Minneapolis metro area, give St Paul Pipeworks a call today.

Yours Truly,

Matthew Dettwiler

Social Media Manager


What’s the difference between a Drum Trap and a P-Trap? Ask A Plumber