Question

treated sewage water is a possible alternative source of drinking water, especially in very dry regions. how can treated sewage water possibly be used as drinking water? the treated sewage water is returned to the drinking water treatment plant and carefully cleaned. the treated sewage is pumped directly back into the drinking water pipes for homes and businesses. the treated sewage is secretly mixed nightly with a citys drinking water and no one knows about it.

Explanation:

Treated sewage water needs to go through proper treatment processes. Pumping it directly into pipes (second option) is unsafe as it may not be fully purified. Secretly mixing it (third option) is unethical and not a proper procedure. Returning it to the drinking - water treatment plant (first option) allows for additional cleaning and purification steps to make it safe for drinking.

Answer:

The treated sewage water is returned to the drinking water treatment plant and carefully cleaned.