Divide the strawberries, water, maple syrup and lemon juice into two 32oz glass mason jars (or one large jar). Stir well to dissolve the maple syrup.
Cover the jars with a clean breathable cloth secured with a rubber band (this keeps dust out but allows natural yeasts to enter).
Leave at room temperature for 2–3 days, stirring once daily. You should start to see bubbles forming and notice a light, fruity fermentation smell.
Once it's bubbly and lightly tangy, strain out the strawberry solids and transfer the liquid into clean flip-top bottles, leaving about 1–2 inches of headspace at the top.
Seal the bottles and leave them at room temperature for 1–3 days to build carbonation. Burp the bottles once a day by quickly opening and resealing them to prevent too much pressure buildup.
Once carbonated to your liking, transfer the bottles to the fridge. Serve cold over ice.
