The easiest way to purify

Nature is perfect, and cleans waters with its "bio-stuffs", by means of the so-called biodegradation. Nonetheless, the overwhelming introduction of synthetic compounds saturates the power of these bio-stuffs.
Then, the easiest way to purify water is ...not to pollute it! We cannot refrain to clean ourselves, or to cook foods, but we can avoid generating excess of waste. To collect litter and properly dispose it even easier. Plastic bags, for example, constitute a prominent source of pollution, but they are into waters or on the wayside just because someone of us left them there.
Who think it is boring to avoid leaving litters outside?