Most people don’t pay attention to the small circular dent on the side of a plastic milk jug, but it actually serves several important functions.

This dent isn’t there for decoration or by mistake — it’s an intentional design feature that helps the jug manage pressure, stay strong during transport, reduce plastic usage, and make recycling easier.

When the jug is filled, the liquid inside creates pressure. The dent works like a flex point that can expand or contract slightly to prevent the jug from cracking or becoming misshapen, especially during stacking or when temperatures change.

It also allows the jug to absorb some impact if dropped, which helps prevent spills or breakage. From a manufacturing perspective, the dent strengthens the jug’s structure without needing extra plastic, which cuts down on material costs and waste. This makes it both economical and more environmentally friendly.

Additionally, the design makes the jug easier to crush for recycling, saving space and making the recycling process more efficient. Some brands even use the dent for visual appeal or branding by adding logos to the indented area. While many people mistakenly think the dent is a flaw, it’s actually a smart solution that makes milk jugs safer, cheaper to produce, and more sustainable. This tiny detail shows how thoughtful design can have a big impact on everyday products.