Wild peafowl live in areas that have big monsoons or rainy seasons but this does not mean that they enjoy a good water bath like we humans do. Peafowl like to forgo the water and instead take a dust bath.
Just like bathing is important for us humans to stay clean and healthy, dust bathing is an important activity for peafowl to keep them healthy. Dust baths can help keep off or get rid of mites and lice. The act of dust bathing can help align feathers.
If you find a depression in your aviary or your yard this is likely a dust bath area. Peafowl will scratch out their own dust bathing bowl. Usually if there is already a sandy or dusty area in their environment they will avoid scratching up the grass and just scratch where they can already see dirt. My peafowl mainly dust bathe in 2 locations in the aviary. One location is a sunny spot and the other is a shaded spot. Since the peafowl can make their own dust bath location you really don't have to make one for them, but if you are worried about them making one where you don't want them to, you can make an area for them and hopefully they will use it.
You can add sevin dust in the dust bath area as an added way to help prevent bugs on your birds and evidently taking wood ash from a fire and putting it down where your peafowl take dust baths is a very good bug deterrent. Recently I added some wood ashes to the dust bathing area and at first the birds were unsure about walking on the wood ash, but the other day I saw my white peahen Snow White dust bathing in the ash. Now, this worried me that it would turn her grey, but it has not.
Finally there is knowing what a dust bathing peafowl looks like. Often people have gotten worried seeing their peafowl sprawled out on the ground sun bathing, so to prevent any heart attacks a dust bathing peafowl will be lying in the dirt scratching the ground with their feet and their beak making sure they tuck dirt/sand/dust around their body. Once they feel like they have broken up the ground enough around them they will flap their wings and dirt will go flying. They will also rub their neck on the ground to be sure that their neck feathers do not get missed as well.
Below shows photos of Ice taking a dust bath.