Is Stainless Steel Safe? BPA, 18/8 Steel and What's Actually in Your Cup
Stainless steel cups and bottles are everywhere these days – and with them comes a question we genuinely like being asked: is this material actually safe to drink from, every single day?
The short answer: yes. Food-grade 18/8 stainless steel is non-reactive, contains no BPA by design and has been the standard material for cutlery and cookware for decades. It is widely considered one of the safest materials you can drink from.
In this guide we unpack what 18/8 actually means, what "BPA-free" really tells you, whether steel changes the taste of your coffee – and how to keep your cup food-safe for years. No scare stories, just clear answers.
Table of Content
The Short Answer
Drinking from food-grade stainless steel is considered safe – full stop. The alloy used in quality drinkware, known as 18/8 or type 304, belongs to the same family of steel your forks, cooking pots and professional kitchen equipment have been made from for decades.
All HEY SAHNI cups and bottles are made from food-grade 18/8 stainless steel and are 100% BPA-free. The material does not react with your drink, does not leach plasticisers and does not hold on to flavours when cleaned properly.
The slightly longer answer is still worth two minutes of your time – because understanding the material is the best protection against marketing fog and internet scare stories alike.
What 18/8 Stainless Steel Actually Means
18/8 describes the recipe of the alloy: roughly 18% chromium and 8% nickel, embedded in iron. That composition is technically known as type 304 stainless steel – the most widely used food-grade steel in the world.
Each ingredient has a job. The chromium reacts with oxygen to form an ultra-thin, invisible "passive layer" on the surface. This layer protects the steel from rust and corrosion – and it repairs itself within moments if the surface gets scratched. The nickel makes the alloy more stable and gives it that clean, slightly warm shine.
Here is how 18/8 steel compares with other popular cup materials:
| Material | Food-safety profile |
|---|---|
| 18/8 stainless steel | Non-reactive, contains no BPA by design, extremely durable |
| Polycarbonate plastic | May contain BPA; scratches easily and can hold on to residues |
| Bamboo-melamine blends | Often bonded with melamine resin, which is typically not recommended for hot drinks |
| Glass and ceramic | Taste-neutral, but fragile and without insulation |
If you want the full picture including paper cups, we compared the most common options here: Reusable vs Disposable Cups.
BPA-Free: What That Really Means
BPA – short for bisphenol A – is a chemical building block used in some plastics, most notably polycarbonate, and in some can linings. The health debate around BPA concerns plastic products, where the substance can migrate into food or drinks under certain conditions, especially with heat.
Stainless steel is a metal alloy, not a plastic. It cannot contain BPA in the first place – there is simply no BPA in the recipe. When we say all HEY SAHNI products are 100% BPA-free, that covers every component, including the lids.
One honest note: on some plastic bottles, "BPA-free" simply means a chemically similar substitute was used instead. With a steel cup, the question never even comes up for the part that holds your drink – and that is exactly the point.
Does Stainless Steel Change the Taste?
No – food-grade 18/8 stainless steel is taste-neutral. The passive chromium layer keeps the metal from reacting with your drink, which is why coffee from a quality steel cup tastes like coffee, not like metal.
If you ever do notice a metallic or stale note, it usually has one of three harmless causes: a brand-new cup that hasn't had its first proper wash yet, leftover residues from a previous drink, or coffee oils that have built up over time. All three disappear with a thorough clean.
This neutrality is also why steel works so well for switching between drinks – espresso in the morning, peppermint tea in the afternoon, sparkling water in between. Nothing carries over.
Keeping Your Cup Food-Safe for Years
A stainless steel cup does not age the way plastic does. There is no material fatigue that releases anything into your drink – with a little care, it stays food-safe for many, many years. Four habits are enough:
- Rinse soon after use, especially after milk-based drinks, so residues never get the chance to settle in.
- Hand-wash the cup body. We recommend this mainly to protect the print – the lid is dishwasher-safe.
- Skip aggressive helpers. Steel wool and chlorine-based cleaners can damage the surface; a soft sponge and washing-up liquid do the job.
- Deep-clean occasionally. A paste of baking soda and water removes built-up coffee oils gently.
We put together the full routine – including how to get stubborn coffee smell out of the lid – in this guide: How to Clean Your Stainless Steel Cup.
FAQ
Can the cup go in the dishwasher?
The lid: yes. For the cup body we recommend washing by hand – mainly to keep the print looking good for years. A quick rinse with warm water and washing-up liquid takes less than a minute.
Are fine scratches on the inside a safety problem?
No. The chromium passive layer that protects the steel repairs itself within moments, even where the surface has been scratched. Fine marks from spoons or ice cubes are purely cosmetic. Just avoid steel wool, which causes unnecessarily deep scratches.
Are acidic drinks like lemon water okay in stainless steel?
Yes. Type 304 steel handles everyday drinks – coffee, tea, juice, lemon water – without any problem. As with any container, don't store strongly acidic drinks in it for days on end; rinse the cup when you're done and everything is fine.
What about a nickel allergy?
18/8 steel contains nickel, but the release from intact type 304 stainless steel is very low – drinking from it is different from wearing nickel jewellery on your skin. If you have a strongly pronounced nickel allergy, play it safe and check with your doctor first.
The Author: Svenja Müller
Svenja is the Social Media Manager at HEY SAHNI and helps share the brand's story, community and coffee culture online. Living on Mallorca and working closely with the brand, she has developed a deep appreciation for great coffee, meaningful rituals and the culture behind every cup.