How to Use a Drain-Cleaning Bladder

Drain cleaning bladder

When you are dealing with a difficult drain stoppage that is due to sludge, build-up, or grease, if a plunger or drain snake doesn't work, you might try a specialty tool known as a drain cleaning bladder. Some old-time plumbers know this little device as a blow bag, and it acts as a heavy rubber expansion balloon with a pressure-sensitive valve release on it. An ordinary water hose is attached to one end, and the bladder is inserted into the clogged drain. The drain bladder fills up with water and closes off any access to it, like a filled water balloon inside of the drain. Once the bladder is full and reaches a certain point of pressure, the outlet opens, forcing a strong stream of water forward that may well clear out the stoppage through the sheer force of the water pressure.


Drain bladders can easily push water and debris into other drains or vents connected to the one you are trying to unclog: For that reason, drain bladders are more typically used outdoors, on drains that aren't vented. Our experts advise against using drain bladders indoors unless you have significant experience using them.

Uses for a Drain Bladder

When do you turn to the drain cleaning bladder for help? In some situations, a drain snake may push through the greasy buildup in the pipe without completely clearing the stoppage. A drain-cleaning bladder can be used on the same line to force the drain open. Once the line is open, you can work on the drain more easily by flushing it out or snaking it again.

Before You Choose

  • The drain cleaning bladder needs to be pushed into a portion of the drain where there is no other place for the water to go. For example, if the stoppage is in a pipe shared with another drain, then using a drain bladder will only force water into the other drain. Also, if there is a vent connecting into the drainpipe between the bladder and the clog, the water will be forced up and out of the vent line. The best place to use a drain cleaning bladder is a clean-out fitting where you can push the bladder into the main part of the drain before turning it on.
  • You do not want to stand behind the drain cleaning bladder. They have been known to pop, and it is possible to get hurt. 
  • If this does not clear the stoppage, it is possible that your drains can be damaged by the water pressure. In drain lines with weak joints, the water pressure can force them apart. It's also possible for backed-up water to come shooting back out of the cleanout where you are working. Again do not stand behind the drain cleaning bladder.
  • Check the specs of the drain bladder to see how much water pressure is recommended. If the water pressure at your home is too great, it may need to be regulated before you can use the bladder.


  1. Attach the drain bladder to a hose that is connected to a cold water hose bib.
  2. Push the bladder down into the drain. It should be inserted a minimum of 6 inches down the drain.
  3. While standing a safe distance away, turn the water on slowly until it is at full pressure. After it fills, the drain bladder will force water pressure into the line and the drain should clear.
  4. Leave the water on for a few minutes before turning it off. Once the water is off, the bladder will deflate. Check to see if there is still standing water in the drain. If there is no water, the stoppage is clear. If there is still water present, try using the bladder again.