The correct answer is based on the established guideline for Total Organic Nitrogen (TON) levels in drinking water. TON is an important parameter because elevated levels can indicate potential water quality issues, including the presence of organic pollutants that can affect human health and the safety of the water supply.
The recommended threshold of 3 or less for TON is significant as it helps ensure that drinking water remains safe for consumption and meets regulatory standards. Maintaining TON at levels at or below this threshold can help reduce the risk of harmful substances coming from organic nitrogen sources, such as fertilizers or decaying organic matter, which can lead to problems like eutrophication in water bodies and can negatively impact water treatment processes.
In contrast, thresholds that are higher, such as 5 or 10, may indicate a lapse in water quality management, which could necessitate further treatment or mitigation strategies to ensure consumer safety. Therefore, the selection of 3 or less reflects best practice in safeguarding public health regarding drinking water quality.