Since they did not have water toilets, it would not be viscous like sewage. It would have consistency similar to a barnyard manure pile. To fill a floor to a d

Since they did not have water toilets, it would not be viscous like sewage. It would have consistency similar to a barnyard manure pile. To fill a floor to a depth enough to "drown" would require several years of collecting, which means it would be well decayed and much closer to soil than sewage. But it sounds too improbable to have happened.