What to Know About Drain Bladders

Updated: Jan. 30, 2024

Learn how a drain bladder can easily and inexpensively blast away the toughest clogs.

The drain bladder is one of the greatest unsung heroes of every plumber’s arsenal. They’re capable of clearing the most stubborn drain clogs, even after all other methods have failed. Along with being highly effective, they’re also inexpensive and easy to use plumbing products. Read on to discover why you should consider a drain bladder for your next clog before resorting to more difficult methods — or calling a plumber.

What Is a Drain Bladder?

Drain bladders are heavy-duty rubber expansion balloons that inject pressurized water into clogged plumbing drains. One end is connected to a standard garden or water hose, and the other end is inserted into the clogged drain.

Once the water is turned on, the bladder builds up water pressure as it expands like a water balloon inside the drain. After the bladder has fully expanded to encompass the entire diameter of the drain, it shoots the pressurized water down the drain until the clog has cleared.

Drain bladders are so effective and easy to operate that they can be used on everything from clogged kitchen sinks (without the elbow-grease other methods require) to heavy clogs from grease or compacted toilet paper that chemicals, drain snakes and plungers can’t bust through. Drain bladders are also less messy than other drain cleaning methods (especially drain snakes). Although some residual drain waste material may cling to the drain bladder after use, it’s often minimal because you don’t have to insert the bladder as deeply into the drain.

While a drain bladder can be safely and effectively used in any type of drain pipe (including PVC, steel and cast-iron), it’s possible the pressurized water emitted from the drain bladder can break fragile pipes. Cast-iron and PVC pipes that are old, brittle or have existing cracks are prone to rupturing under high water pressure, especially when attempting to clear a heavy clog. It’s not recommended to use drain bladders on old drains of questionable quality.

It’s also recommended that you avoid placing the drain bladder directly into a sink drain because the water pressure may damage the P-trap, and the force from the expanding bladder may damage the fixture. However, many professionals successfully use drain bladders to clear clogged P-traps, and some manufacturers advertise their bladder’s safe use directly in the sink basin’s drain. If you decide to use a drain bladder for this purpose, ensure that the bladder is completely inserted into the drain opening, and closely monitor the P-trap for signs of damage while the bladder is in use.

Finally, drain bladders work best when there are no tees, elbows or other ways for the water to be diverted between the clog and the drain bladder.

Because water takes the path of least resistance, the water from the drain bladder may travel away from a heavy clog if there’s anywhere else for it to go. For example, since a bathroom sink drain splits off in two directions when it enters the wall (one down to the main waste line and the other up to the roof vent), using a drain bladder on a heavily clogged bathroom sink drain may result in the water backflowing up towards the roof. This can be avoided, however, if the drain bladder is inserted past the tee in the wall where the drain splits off.

Buying a Drain Bladder

Drain bladders are available in small, medium and large sizes to fit inside any household drain pipe. Small drain bladders can be used on one- to two-inch-diameter drain pipes, medium drain bladders are made for 1-1/2- to three-inch pipes and large drain bladders are designed for three- to six-inch drains.

Because 1-1/2- and two-inch sink and shower drains are the most likely to clog, a small or medium-sized drain bladder is a good general-purpose option that should handle the majority of your clogs. A large drain bladder can be used if your clog is in the three- to four-inch main sewer or septic lines.

You can purchase drain bladders individually when the need arises, or you grab a combo pack with all the sizes you could need to be ready for whatever comes up (or won’t go down!). Each size will cost between $10 to $20 apiece. Or you can buy a drain bladder kit with different sizes and accessories.

Tips for Using a Drain Bladder

Drain bladders are incredibly easy to use. Once you’ve acquired the properly sized drain bladder for your clogged pipe, take the following steps to blast away the clog:

  1. Connect your drain bladder to a water hose, and connect that hose to a water faucet.

  2. Insert the drain bladder at least six inches into the clogged pipe.

  3. Slowly turn on the water and allow the bladder to expand as the water pressure builds.

  4. Keep the water running for a minute or two, or until you see the drain is cleared.

  5. Inspect the drain to ensure the clog has cleared. If not, repeat the first four steps until you are successful.

  6. Shut the water off and wait for the bladder to deflate. Remove the bladder from the drain and disconnect the drain bladder from the water hose.

If the drain fails to clear after several attempts, try another drain clearing tool or consider contacting a professional plumber.