A family can save over 50,000 gallons of water per year by recycling graywater." The most reliable source of this information is a plumber salesman scientific website journalist

i would say plumber. i'm sorry if its wrong

scientific website

Explanation:

Gray water can be defined as the household wastewater which comes out from bath water or showers, laundry water, lavatory (basin) water, and untreated kitchen and washroom water.

But by treating these gray water we can save a lot of water and the water can be made to use for other purposes such as for gardening or other things which do not require clean water. But cleaning or treatment methods of such water is very expensive.

So this information can be a useful source for a scientific website where such different treatment methods of gray water may be published.