Good suggestions above! I’d also add that if you do want to occasionally use a pesticide/herbicide, you should plant out your garden more densely first. That way, the amount of runoff that occurs after rain will be minimized. Also, if you try and conserve water whenever possible, this actually contributes towards preventing water pollution. This is because the more fresh water we have in reserve, the less contaminated water we need to treat and use. And last (but certainly not least), make sure you don’t litter. If you’re down the beach and your chip packet blows away, chase after it, don’t just let it blow away.