While it is not normally recommended that you clean your UGG boots with water you will have an occasion or two where it’s absolutely necessary. If you care for your UGG boots carefully you won’t cause them any significant damage.
Start by wetting your boots with cold water. Run them quickly under the water but do not submerge them in an effort to soak them. Your boots came with an UGG Shampoo & Conditioner product. If you still have it, gently scrub the exterior of your boot with a soft brush (like a toothbrush).
When you are finished scrubbing, wet the boot again with cool water to rinse off the excess shampoo product.
Now for the complicated stuff. You really can’t put your UGGs in the washer or dryer but you’ve probably gotten a lot of water in them by this point. Place your boots in the washer on the spin cycle, only for a minute or two. This will help to draw some of the excess water out of the boots.
Take them out of the washer, stuff them with paper towels or newspaper to make sure they keep their shape, and place them in a warmm, dry place to finish drying. Do NOT put your boots near a window, heater, or near a lightsource as these will cause excessive shrinkage.
In the end, your boots will likely shrink slightly because of the washing process. Wearing them for an hour or two will stretch them back to their original size and – of course- the dirt and grime stains should be gone.