Why Water Bottles Start Leaking

You would never leave your house without the essentials: phone, wallet, keys. What about your water bottle? Making a habit out of carrying a water bottle is good for the environment and reminds you to stay hydrated. But when there is a leakage, it becomes an inconvenience.

Reusable drinking bottles leak due to a number of factors, depending on the bottle’s type, material and lid design. Some models tend to crack while others fail to seal properly. In many cases, a simple clean-out may stop it from dripping.

In this post we explain the causes and solutions to those leaks so that your water bottle does not become disposable. We will also cover how different bottle materials may be more prone to leaks and why. Plus, we will explain the different ways you can check for leaks, as well as how to clear blockages.

Types of water bottles

As consumers become more conscious of the environmental impact of disposable plastic, the demand for water bottles increases. Initiatives to enhance portability, durability and insulation translate to innovations in materials and features.

Choosing the right drinking bottle depends on its expected purpose, size, look and your preferred material. The most common materials are: 

  • Plastic
  • Glass
  • Stainless steel
  • Aluminum
  • Copper

Each material offers specific qualities to suit your requirements and preferences.

For example, glass is heavy and provides poor insulation, but the taste and quality of the water is ideal. As glass breaks easily, you may have to deal with leakages coming from a crack in the body of your bottle.

While plastic is versatile and affordable, it ages quickly and produces odors. Leakages in plastic bottles generally emanate from the mouth or the bottom.

Stainless steel is usually the most portable and durable option, although it is prone to dents from which water can drip. 

Types of lids

Many leaks develop around the lid. The quality of the bottle cap will influence the chances of leakages. Some of the lids available in the market are: 

  • Screw-top lids
  • Sports caps with nozzle
  • Sports caps with spout

Screw-top lids are often linked to wide-mouth bottles, usually made of stainless steel or glass. Nozzles are generally made of plastic and some have an automatic closing valve that prevents spills. Spouts tend to be made of rubber with a splash-safe flipping mechanism. The most common lid material is plastic, although there are some stainless steel options available. 

Reasons why your water bottle is leaking

If you notice water dripping from your bottle, the first thing to do is to locate the leak. You can empty the bottle and place it in a container filled with water. Hold it under the surface and look for bubbles to identify any punctures.

When your bottle empties rapidly, the leakage is probably caused by a crack.

If the loss of water is slow, which you can measure by marking the water level and observing its decrease, there is probably a small hole.

If you see or feel with your hands that the water is coming from the mouth, there are a number of possibilities as to what causes the spillage. 

When your water bottle is quite new, the manufacturer might be able to replace the damaged parts or the entirety of the product. If the malfunction is due to the natural wear and tear from aging, there is still a chance that you can replace the worn elements to restore your bottle.

Here are the main reasons why your water bottle is leaking and the ways in which you can fix them: 

1. Loose/tight cap

Screw-top lids have a specific torque range to ensure proper sealing. Too little torque means that the cap is not tight enough, causing the seal to fail. When the lid is made of soft plastic, too much torque can loosen the closure by stripping the threads or wrinkling the liner within the cap. In both cases, the solution is to test your bottle and discover what is the right amount of force you need to apply to seal correctly. 

In copper bottles, an obstruction or roughness on the thread of the lid may be preventing it from sealing. Fix it by twisting and untwisting it a few times until the threads are polished by friction. 

2. Cracks or holes in the body

Dents, punctures and cracks in your bottle will definitely produce leaks. You can place waterproof tape over the crack as a temporary fix until you get food-grade silicone sealant to repair your bottle. 

3. Issues with the rubber gasket within the lid

Some screw-top lids have gaskets lining the inside to make them fluid-tight. A regular problem with rubber gaskets is that they hold moisture and collect mold over time. Not only can this create leaks but also presents a health hazard. Removing the gasket, washing it separately and letting it dry before putting it back inside the lid is a good way to prevent this issue. 

The natural aging of a rubber gasket makes it break down slowly. This is accelerated when you use your water bottle for hot beverages. The sealing capacity of your lid is diminished when the gasket is worn down and can only be restored by replacing it with a new one. Contact your bottle’s manufacturer to get a replacement.

Gaskets are supposed to fit tightly into the lid to ensure optimal sealing. Over time, it is likely for them to stretch, move around and even fall. Again, the only solution is to contact the manufacturer to request a replacement, which might be covered under the product’s warranty. 

4. Clogs/blockages in spout or spigot

If your rubber straw is leaking, you might have debris built up in the vent valve. Turn the cap over and locate any trapped object. In most cases, you will be able to easily remove it with a toothpick, taking care not to damage the material. If this does not work, gently peel back the rubber seal and clean the area.

As a last resource, try dismantling the mechanism making sure that you do not lose any of its parts. Clean any accumulated dirt and cautiously reassemble the elements. 

5. Other reasons

Old bottle mouths might have worn or rusty threads that make it difficult to twist the lid into its position. A misplaced lid will surely lead to leakages. You might need to clean the threads, replace the lid or even purchase a new bottle. If your bottle is too full, the weight of the water can create enough pressure to overflow. Shake the bottle after closing it to check whether there is any water coming out.

Crafty people might be able to fix cracks in a bottle’s cap, and resourceful individuals might find clever replacements for broken lids with some DIY inventions. 

Water bottle sweating

Condensation takes place when the content of your bottle is colder than the ambient air. 

The surface of the bottle comes in contact with the moisture in the air, which turns from gas into liquid and sits on the walls of the bottle. 

This can make any stainless steel, glass or plastic water bottle drip, making everything around it wet. High quality insulation with double walls prevents condensation. Consider investing in superior technology when you enjoy drinking cold liquids.

A home remedy is to dress your bottle with fabric or foam, or even slip it into a sock to absorb the moisture.

Water bottle went yellow

Red, orange or yellow colorization may be caused by small amounts of rust in your water system. But when you notice yellow slime building up on the inner part of your water bottle or inside the lid, you are probably dealing with bacteria. 

Sediments of rust or biofilm created by bacteria should be washed off the bottle immediately, after which you should sanitize the bottle and its lid. Stainless steel and glass water bottles are easier to clean, thus harder for bacteria to thrive in.

Water bottle went green

When your water bottle is exposed to sunlight, warmth or moisture, it creates a perfect environment for green algae to grow. This is the reason why you see green slime expanding inside your bottle.

Although it is not necessarily harmful, it is not ideal in the long term. Fill your bottle with a solution of one teaspoon of bleach to one cup of water, cover and shake to coat the whole interior. Add hot water and soak for half an hour. Empty the bottle, scrub any remaining green stains and rinse well. Repeat if necessary.  


The inefficient use of water bottles defeats their purpose of reducing plastic waste to protect the environment. We recommend that you do not take the decision of purchasing a reusable bottle lightly. If you choose the model and material that suits your needs, you will minimize the risk of leaks and other problems. Keep your bottle clean to ensure the quality of your drinking water remains safe, and try our solutions mentioned above to extend its lifespan.

Russell Singleton

Russell has a Bachelor of Science (Environmental and Marine Geoscience) with Class I Honors. He is currently completing his doctorate in science and is passionate about all earth processes, especially isotope geochemistry and paleohydrology.

Recent Posts