Ideally, septic tanks should be installed somewhere with level ground. Additionally, the tank should be located on high ground to prevent flooding whenever possible. Finally, you should keep an eye out for steep slopes or dense tree roots that could damage your septic system.

The best place for a septic tank as per Vastu is in the north-west or south-east direction of the house, away from the main entrance and living spaces. As staircases are mostly found outside the houses, you can place a septic tank under the staircase as per Vastu Shastra guidelines.