You can unclog a drain filled with cat litter without damaging the plumbing or the sink. Cat litter often clumps and expands when exposed to moisture. This design feature can work against it when going down a drain. Cat litter clogs can completely cut off the flow of water through a drain pipe. Water pressure on the clog can be taken advantage of to push the cat litter clump on down the drain pipe.
Lift out and set aside the drain basket, plug or stopper. Turn the water on until the drain pipe overflows and begins filling the sink. Cover the drain opening with the plunger and allow the water to continue to run until the rubber plunger head is mostly submersed.
Press straight down firmly on the plunger handle until the rubber head collapses into the drain opening. Pull straight up on the plunger handle until the rubber head regains its convex shape. Thrust straight up and down vigorously with the plunger until the water in the sink begins to drain.
Scoop the water out of the sink with a cup, if the drain is still clogged. Dump the scooped water into a working drain or outside.
Press the end of a water hose to the opening of the clogged drain. Turn the hose on and off in one second intervals to send powerful pulses of water down to the clog. Scoop the accumulated water from the sink, if the drain remains clogged.
Extend the drain auger into the drain opening until you feel resistance from the clog. Turn or twist the auger into the cat litter clog. Test the drain by running water into it.
Place a bucket below the bent drain pipe under the sink if the drain is still clogged. Disconnect both ends of the bent pipe, also called the trap, with a pipe wrench. Push out the clog with a long screwdriver.
Reinstall the cleared pipe. Place the drain stopper, plug or basket back into the drain opening.