What minimum distance should be maintained between an Earth Privy and a well with watertight casing to a depth of 4 meters?

• A. 10 m
• B. 20 m
• C. 30 m
• D. 50 m

Answer: (C)

The important idea is protecting drinking water from contamination by waste seeping through the ground. An earth privy (pit latrine) releases liquids and pathogens that can travel through soil with percolation. Even if a well has a watertight casing to a depth of 4 meters, that casing isn’t a guaranteed shield against all migration of contaminants. The distance between the privy and the well determines how much time and space the leachate must travel before it could reach the water source, allowing dilution and attenuation.

Thirty meters is the standard minimum distance recommended in many practice guidelines for a pit latrine near a well with a deeper, protected casing. This distance reduces the chance that waste water pathogens or nitrates reach the well, given typical soil conditions and groundwater flow.

Shorter distances (like ten or twenty meters) provide less separation and higher risk of contamination, while a much larger distance (fifty meters) is more conservative than necessary under common guidelines for a well with proper casing.