If your cesspool is backed up, there are several signs to look out for. First, check for an overflowing cesspool or septic tank. If you notice gurgling sounds coming from your toilet or drains, it could indicate a blockage. Slow drains and toilets that don't flush properly are also red flags. Another sign is a lush green lawn or pooling of water near the septic area. If you observe any of these signs, it's essential to address the issue promptly to prevent further damage and health hazards.