All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
First of all, we advise you not to open the door of whispering as this is a widespread evil; for more benefit on how to deal with whispers, please refer to Fataawa 92050 and 92641.
As regards your question about whether or not you are obligated to wear absorbents, then the answer is that according to the view of many jurists avoiding impurities is an obligation in itself even if the person is not preparing himself for the prayer. Based on this opinion, you must avoid impurities whether by wearing an absorbent or by putting a pad or by any way that prevents the impurity from reaching your body or clothes, and you are obligated to take off the pad [absorbent] when you wish to perform the prayer and then you must wash and clean yourself before performing ablution because cleansing oneself from impurities is a condition for the validity of the prayer. This is of course if you are sure that you had some impure discharges, and the matter is not just a doubt or a whisper.
Indeed, the jurists all agree that one is obligated to perform the prayer in pure clothes and if his clothes become impure and he wants to pray in those clothes, then he must wash the impurity.
As regards the drop of urine being mixed with the water of the bucket, then if this is known with certainty and the water is not a big quantity (i.e. it is less than 192 liters of water as estimated by some scholars), then the water becomes impure according to the majority of the scholars; however, if the water is more than this amount, then it does not become impure unless its smell, color or taste changes with those drops of urine; this is of course if you are sure about the impurity and it is not a mere whisper or doubt.
Moreover, the doubt about the lower part of the leg being impure should not be taken into account as, in principle, things are pure and not impure, and you are not obligated to wash any of your clothes unless you are sure that they are stained with impurity as we mentioned, in which case, you must wash only the part that is stained with impurity.
Furthermore, many jurists are of the view that a small amount of impurity is absolutely excused, and this is the view chosen by Ibn Taymiyyah and it is permissible for a person who has whispers to act according to this opinion.
Allaah Knows best.