Frequently Asked Questions

Most questions received at Simple Flask are listed and answered below. For any more questions, please send an email to will reply our email within hours.

Products and Material

All our water bottles and containers are 100% free of BPA, BPS and BPF. Our products undergo rigorous third-party testing to ensure that harmful chemicals do not penetrate food or beverages. Independent researchers also performed extraction tests to ensure that our bottles and containers meet the stringent food safety standards set by the FDA, European Community, Japan’s Ministry of Health and Welfare, California Proposition 65. BPA, BPs, and BPF are not used in raw materials or manufacturing processes for making our water bottles or containers.
For decades, scientists have conducted extensive research on BPA, and the results have shown that the chemical plays a role in early pregnancy abortion, placental disease, and various adverse health consequences after birth. These adverse health effects are becoming more widely known.

Almost everything (milk, juice, tea, coffee, sports drinks) can be used as long as the water bottles are cleaned after each use. We do not recommend placing carbonated drinks in stainless steel water bottles with a straw cap, as pressure can cause liquid to spray out of the straw.
We do not recommend keeping hot milk in vacuum flask for long periods of time, as harmful bacteria can grow.

Of course you can! If you are using a Simple Flask water bottle with a straw cap, be aware that changes in pressure will force liquid into the straw, which may cause the beverage to suddenly spit out of the sip part the first time you use it. After taking off, carefully open the water bottle. You can release the pressure by unscrewing the lid a quarter of a turn before you open the straw lid.

We do not recommend freezing stainless steel thermos or glass bottles in the refrigerator. If you like extra cold water, you can fill water bottle with ice cubes.

Yes, hot beverages are fine – in fact, many consumers like to put hot tea or boiling water in a thermal insulated stainless steel bottle before going for outdoor sports in the cold season. Some consumers buy vacuum cups because they use hot cups to store hot coffee.

When we design children’s water bottles and food containers, we put safety first, which includes rigorous third-party testing of BPA, lead, and other harmful substances. We have also independently tested the bottles to ensure there is no risk of suffocation or broken parts associated with children.
We strictly monitor the production process of manufacturers to ensure that harmful substances do not contaminate our products during the production process.
Congress and the Consumer Product Safety Commission (CPSC) have recently strengthened safety standards in response to public concerns about product safety. We actively support these improvements and ensure that all of our products fully comply with new rules and reporting requirements.

No. Simple Flask kids drinking cups are fully compliant with US and EU child safety laws, including consumer product safety committee standards that regulate lead in inks.

No. Metal water bottles cannot be heated in a microwave oven.

Our food grade stainless steel (18/8 stainless steel) for vacuum insulated double wall stainless steel water bottles has anti-fouling, anti-scratch and anti-corrosion effects, and naturally has no taste or odor.
Aluminum bottles are lighter but must be made with a lining or coating that usually contains chemicals and undisclosed ingredients. These linings and coatings are harmful to the human body and are not environmentally friendly. The research results of our &D personnel show that hard and pure slightly heavier stainless steel bottles are more in line with consumer needs and more environmentally friendly. This is what we make.

Most of our stainless steel containers can be customized.

We use laser marking technology to mark the surface of stainless steel containers. If your purchase amount is large, we may arrange silk screen. Of course, we use laser marking by default.

Our production schedule changes daily, depending on the overall order volume. We will process all orders on a first come, first served basis and guarantee that we will make every effort to transfer your order to you as soon as possible.

Care and Use

The Simple Flask stainless steel container can be easily cleaned with a bottle brush using warm water, vinegar, soda or neutral soap. Before first use, wash the stainless steel water bottle with hot soapy water by hand. Rinse the bottle.

The lid can be washed in the top bracket of the dishwasher, or it can be washed with warm soapy water.

Manual cleaning method: For deeper cleaning, add a drop of mild soap to a clean glass bottle filled with water. Place the pipette and cap into the solution, then tighten the cap. Shake the mixture for 30 seconds, then soak the parts for about 15 minutes. Rinse and shake.

  1. Wash the water bottle with a bottle brush, and use as many bottle brushes, straws, and lid cleaning kits as possible.
  2. Wash with a neutral detergent.
  3. Use baking soda for cleaning: For stubborn spots in Simple Flask, mix 2-3 tablespoons of baking soda with a small amount of warm water to form a scrub. Dip the bristles of the bottle brush into the paste, then dip the paste into the affected area inside the flask. Repeat as needed until the stain disappears.
  4. Wash bottle caps in the dishwasher: In order to clean the lid, the safest is the dishwasher rack. It can be used longer if the lid is washed by hand, but a dishwasher can be used if deep cleaning is required.
  1. Pass the Simple Flaks through the dishwasher or immerse the outside in hot water. Repeated exposure to high temperatures can cause discoloration of powder coatings.
  2. Put Simple Flask in the refrigerator: Due to the double-layer vacuum insulation, the water in the refrigerator can be protected from low temperature and it will not freeze. If you want cold water, put some ice cubes in the flask.
  3. Place the flask on the stove: Because the flask has a double-layer vacuum insulation, the external temperature will not change the internal beverage temperature. If the flask is placed on any type of stove or heat source, heat can damage the outside of the flask.
  4. Use bleach or chlorine to clean our products: these chemicals can damage stainless steel and rust. Therefore, they should not be used on our products.
  5. Put too much hot water, it will leak.