My very old home has a stacked stone cesspool. The cesspool used to leach fairly well for years, but grease and sludge have built up over time, and the leaching started to fail. We pumped the cesspool and re-filled with water. My plumber added caustic soda to clean a significant amount of grease and sludge build-up. It's been 48 hours, and the water level in my cesspool hasn't gone down yet ... it is still pretty high ... and we haven't added much water to the system. My question is how long will caustic soda chemically react to dissolve grease and sludge? When will the grey water become inert, such that it would be safe to pump it if it gets too high? It is winter, so outside temps fluctuate between just below or above freezing.