You've just ordered a watch from Time2Seiko, or you're seriously considering it. And the question always comes up at the same moment: is it water resistant? In the shower in the morning? At the pool this summer? That's a fair question for a watch costing 200-400 euros. Here's an honest answer, with no overselling.
Straight answer: a water-resistant Seiko mod assembled by Time2Seiko copes very well with everyday water: rain, hand washing, splashes. And since 2026, on our SEIKOJUST, SEIKOMARINER and SEIKO GMT families, an enhanced 10 ATM (100 metres) water resistance option lets you go as far as swimming. One condition, always the same: the crown must be screwed down.
A Seiko mod isn't a modified Seiko: understanding what we deliver
This is the point most people miss, and it changes everything about perceived quality. At Time2Seiko we don't take an existing Seiko watch apart and touch it up. We assemble each watch part by part, to order, around an authentic movement (NH35 or NH36 calibre depending on the model), with components chosen by the customer: case, dial, hands, sapphire crystal, bracelet.
It's closer to artisan watchmaking than to tuning. Every part is selected, adjusted and fitted by hand in our workshop in France. Nothing is salvaged from a used watch. Nothing is rushed.
Why does that matter for water resistance? Because when you assemble a watch from scratch, you control every step:
- O-ring gaskets are brand new, never compressed or reused
- The crystal gasket (between the sapphire crystal and the case) is greased with the exact amount of waterproof silicone grease before fitting
- The crown gasket is selected at the right diameter for the chosen case
- The case back is closed to the correct torque
Across more than 500 watches delivered to date, we have had no returns and no complaints related to water resistance. Not one. That's the result of careful assembly, not a marketing promise — and it's reflected in our 50 published customer reviews, averaging 5 stars out of 5.
What determines water resistance: ATM ratings explained clearly
ATM stands for atmosphere, the pressure unit used to measure a watch's water resistance. One ATM equals the pressure of a 10-metre column of water under static laboratory conditions. In practice, moving your arm through water generates far higher dynamic pressure. ATM figures should therefore not be taken literally.
| Rating | Permitted use | Real-world examples |
|---|---|---|
| 3 ATM / 30 m | Light splashes | Rain, hand washing, splashes |
| 5 ATM / 50 m | Contact with water | Gentle swimming, shower (crown screwed down) |
| 10 ATM / 100 m | Active swimming, snorkelling | Pool, sea, water sports |
| 20 ATM / 200 m | Scuba diving | Technical diving |
Three levels to choose from, depending on your watch and your habits
As standard, our watches handle rain, hand washing and splashes without difficulty. That's enough for normal everyday use, and it's what most customers receive when they don't plan prolonged contact with water.
At checkout, you can choose enhanced water resistance:
- On SEIKOJUST, SEIKOMARINER and SEIKO GMT, two levels are offered: 5 ATM (50 m) — €14.99 for showering and prolonged contact with water, or 10 ATM (100 m) — €19.99 to swim, go to the pool, to the sea and snorkel.
- On the other families (SEIKODATE, SEIKOAK, SEIKOLUS, SEIKONA, SEIKODWELLER, SEIKONAUT, SEIKOCUB…), the 5 ATM (50 m) — €14.99 option is available: shower and prolonged contact with water without worry.
This difference isn't commercial, it's technical: the case construction and crown type of those three families make 100 metres achievable, which integrated-bracelet cases, day-date dials and chronographs with pushers do not allow.
In every case, one condition never changes: the crown must be fully screwed down before any contact with water.
The crown: the only real point of attention
The crown is the small button on the side of the case used to set the time. It's also the main point where water can enter any watch, Seiko mod or not. When it's properly screwed against the case, the gasket it compresses ensures water resistance. When it's pulled out to set the time and you forget to push it back and screw it down, that protection disappears.
That's why our 2-year warranty doesn't cover water resistance. Not because our watches are fragile around water, but because it would mean making you a promise we cannot keep on your behalf. If the crown isn't screwed down and water gets in, that isn't an assembly fault: it's a forgotten step.
Our 2-year warranty covers any fault the watch might develop: movement, finishing, components. Everything leaving our workshop is checked before shipping.
What you can do with your Seiko mod, level by level
| Use | Standard | 5 ATM option | 10 ATM option |
|---|---|---|---|
| Rain, hand washing, splashes | Yes | Yes | Yes |
| Washing up, cooking | Yes | Yes | Yes |
| Daily shower | We recommend removing it | Yes, crown screwed down | Yes, crown screwed down |
| Swimming, pool, sea | No | Not advised | Yes, crown screwed down |
| Snorkelling | No | No | Yes |
| Scuba diving | No | No | No |
Three habits that extend the life of your gaskets, whichever level you choose:
- Check the crown before any contact with water: two seconds, one habit
- Rinse with fresh water after the sea or a chlorinated pool: salt and chlorine attack gaskets over time
- Have the gaskets checked every 2 to 3 years: silicone ages, even without incident
To explore all our models assembled in France, browse every watch with its 2-year warranty.
Frequently asked questions about Seiko mod water resistance
Is a Seiko mod water resistant?
Yes, provided the crown is properly screwed down. Our watches are assembled part by part with new gaskets greased with waterproof silicone. Across more than 500 watches delivered and 50 published customer reviews (5/5 average), we have had no returns related to water resistance.
Can you swim with a Seiko mod?
Yes, with the 10 ATM (100 m) option, available on the SEIKOJUST, SEIKOMARINER and SEIKO GMT families for €19.99 at checkout. Pool, sea, snorkelling: no problem, with the crown screwed down. Without that option, we recommend removing the watch before swimming.
What's the difference between the 5 ATM and 10 ATM options?
5 ATM (50 m) covers showering and prolonged contact with water. 10 ATM (100 m) adds active swimming and snorkelling. On SEIKOJUST, SEIKOMARINER and SEIKO GMT both options are offered side by side, so you pick the level that matches how you'll wear it. On the other families only 5 ATM is technically possible, as the case construction cannot reach 100 metres.
Can you wear a Seiko mod in the shower?
With the enhanced option (5 or 10 ATM) and the crown screwed down, yes. On the standard version, we still recommend taking the watch off: forgetting the crown happens quickly, and the combination of heat, steam and cosmetics wears gaskets faster. Hand washing, rain and splashes are never an issue, whichever version you have.
How do you check a Seiko mod's water resistance?
The basic step: make sure the crown is screwed down before any contact with water. If you have doubts about the gaskets (condensation under the crystal, a feeling of moisture), take the watch to a watchmaker for a check. Gaskets should be inspected every 2 to 3 years, even without incident.
Is the enhanced water resistance option available on every watch?
Not at the same level. The 5 ATM (50 m) option is available across our whole range. The 10 ATM (100 m) option is reserved for SEIKOJUST, SEIKOMARINER and SEIKO GMT: on those three families both levels are offered and you choose the one that matches your use. You choose the option directly on the product page, before adding to cart.
In closing
A Time2Seiko watch means more than 500 watches assembled part by part in France, new gaskets greased at every build, 50 customer reviews averaging 5 stars out of 5, and zero returns related to water resistance since launch.
If you want to be able to swim with your watch, choose the 10 ATM option on a SEIKOJUST, SEIKOMARINER or SEIKO GMT. And keep the one habit that really matters: check that the crown is screwed down before going near water.
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