Bought this old house, had the septic tank pumped out, drain pipes to drain field still block up. Put a garden hose in the drain pipes, out comes this white sludge. Turns out the previous owner constantly flushed kitty litter down the toilet, and when that stuff gets wet, it turns into a sludge. What to do? Rip out the pipes and start over? Or is there any way to clean the pipes out?