Is the kitchen floor considered ritually impure after sewage water has flowed over it, and how can it be purified in the absence of a drain for running water?

It is sufficient for purifying land from sewage impurity to pour water over it and make it abundant until it covers the entire surface. The separation of the water used for purification from the land is not a condition, because land and similar things are purified by abundance, even if the water used for washing does not separate from it. One should be warned against opening the door to obsessive doubts (waswasah).