What type of flood hazard is acceptable for a drainfield?

A drainfield must be located in an area that is not subject to flooding to function effectively and protect public health and the environment. When a drainfield is flooded, it can lead to the saturation of the soil, resulting in ineffective sewage treatment. Flooding can cause sewage to back up into homes or surface waters, creating a serious health hazard and environmental contamination.

Therefore, the only acceptable flood hazard level for a drainfield is "None." This means that it should be installed in a location that is not inundated during any weather condition, ensuring that the system operates properly year-round. This standard helps to prevent not only the direct complications associated with flooding but also long-term degradation of the site’s soil and increased risks to public health.

In essence, for the proper functioning and safety of on-site sewage facilities, no flood hazard is permissible where drainfields are concerned.