Strong chemical herbicides, pesticides, and fungicides can end up polluting our drinking water, our groundwater, and surface water, so it’s important to consider the longer term effects of using them, and to instead make the choice to use a gentler herbicide, which won’t contribute to the larger issue of water contamination.

Here are some non toxic ways of killing weeds :

• Boiling Water – Simply pour directly over weed plants to kill them. Pro Tip : Repurpose boiling water after suing to boil pasta/potatoes.
• Salt – Sprinkle pinch of salt at base of offending plant to kill it.
• Newspaper – Smother low growing weeds with several sheets of newspaper. Lack of sunlight will exterminate them.
• Vinegar Douse – Spray directly with white vinegar or apple cider vinegar, but be sure not to spray on other plants, works best on sound weed plants.
• Cornmeal – Scatter in area to keep any seed from growing into a plant. Idea for areas you plan on planting grown plants in.
• Borax – Sprinkle in cracks/crevices where you have seen weeds grow. Keep away from beneficial plants.
• Mulch – Cover soil with mulch to prevent weeds from growing in the area.
• Baking Soda – Pour on top of weeds growing in cracks on prive ways and side walk, sweep excess into cracks.
• Vodka and Dish Soap – Mix 1oz vodka, few drops of liquid dish soap and 2 cups water in spray bottle. Apply to broad leaf weeds that grow in direct sunlight.

Reference : https://img.wonderhowto.com/img/12/17/63535214221184/0/9-non-toxic-diy-techniques-for-killing-weeds-your-garden.w1456.jpg