What is the minimum land area requirement for a public water supply with soil type 4?

The minimum land area requirement for a public water supply with soil type 4 is correctly identified as 18,000 square feet. This requirement is based on the necessary space to ensure the effective function of public water supply systems and to maintain adequate separation from potential sources of contamination in the environment, which are critical for protecting public health.

Soil type is an important factor as it influences water movement, filtration, and the overall ability of land to absorb and manage water, which is essential for ensuring the water supply remains clean and safe for consumption. In this context, having a larger area such as 18,000 square feet allows for maintaining proper buffers and management strategies around the water supply, reflecting the need for a more extensive area to mitigate risks associated with runoff and contamination, particularly in less permeable soils classified as type 4.

This requirement is often established based on regulatory guidelines that seek to prevent contamination risks while ensuring adequate water quality for the public. Other given options do not meet the established legal requirements for soil type 4, reinforcing the correctness of the choice for 18,000 square feet.