This is exactly the kind of small, everyday decision where "just grab a bottle" quietly costs you money all year. Mio doesn't care about vibes — here's the math.
Short version: yes, per Japan's waterworks standards. Tap water in Japan is treated and tested against a legally-regulated set of drinking-water quality standards, and it is safe to drink in almost all of the country. What does vary is taste and hardness by region — most of Japan is soft water, and some areas taste better than others. If you dislike the taste, that's a flavour problem, not a safety problem — and it's the exact problem a filter jug solves cheaply.
Tap costs a few tenths of a yen per litre — effectively free at the point of drinking. A filter jug (Brita-style) adds a small amount per litre for replacement cartridges, mainly to improve taste. Bottled water from a supermarket or convenience store is the expensive option — you're paying for packaging, transport, and the store margin, not for safer water.
| Option | Cost per litre | Annual cost (~2 L/day) |
|---|---|---|
| Tap water | ≈ ¥0.2–0.5 | ≈ ¥150–370 |
| Filter jug (taste) | ≈ ¥3–8 | ≈ ¥2,200–5,800 |
| Bottled water | ≈ ¥50–100+ | ≈ ¥36,000–73,000+ |
So a bottled-water habit can cost tens of thousands of yen a year versus a few hundred for tap. Even the filter jug — the "nice taste" option — is roughly ¥30,000+ per year cheaper than bottled, while still delivering almost all of the price advantage of tap.
Many people buy bottled water assuming it's safer than the tap. In Japan that assumption usually doesn't hold — the tap already meets the drinking-water standard. So the bottle mostly buys you convenience and taste, at 100–500× the price. If taste is the real issue, a filter jug or a filtered pitcher gives you most of the taste benefit for a tiny fraction of the bottled cost.
Smart middle path: drink tap for cooking and most glasses; keep a filter jug in the fridge for cold, better-tasting drinking water; buy the occasional bottle only when you're out and about — not as your default supply.
Drink the tap — it's safe per Japan's waterworks standards and costs almost nothing. Add a filter jug if you care about taste. Reserve bottled for convenience only. The "right" answer isn't about what feels cleaner — it's about not paying 100–500× per litre for water you already have at the sink.