Is it permissible to perform tayammum for janabah when there is no pure place for ghusl, due to the presence of impurity in the bathing area that would necessitate re-washing and prolong the process? What is the ruling on splashed water that is less than two qullas? And should past prayers performed with tayammum in this situation be repeated?

It is disliked to perform ablution (wudu') or ritual bathing (ghusl) in impure places to avoid misgivings (waswasah) and the defilement of the one purifying himself. It is obligatory to purify oneself with water to perform prayer for someone who is in a state of ritual impurity (janabah), and dry ablution (tayammum) is not permissible except in the presence of a legal excuse, such as illness. Impurity can be removed from toilets, floors, or walls with water and cleaning tools, and it is not a condition to pour a large amount of water to remove the impurity. If any impurity touches the one purifying himself, he should wash the affected area after completing the ghusl. It is obligatory to make up the prayers that were performed with tayammum when water was available for use, because purity is a condition for the validity of prayer.