Tank Diary

A household collecting rainwater into a storage tank usually manages it by
feel - a glance at the water line, a guess at how many days are left, a
rough impression of how much the last good rain actually gave. None of
that is written down, so the same guess gets made again next month,
sometimes wrong in the direction that matters.

Tank Diary replaces the guess with a record. Check the tank and log what
it holds right now - that's the only thing you ever have to do. The app
works out for itself whether the level went up since last time (a rain
filled it) or down (it's been drawn on), and turns that history into a
real days-remaining figure: not a guess, but a projection worked out from
how the level has genuinely been dropping recently. Below a certain amount
of real evidence, it says plainly that there isn't enough of a pattern
yet, rather than a confident-sounding number built on a single reading.

A separate view, Harvest, totals up every rain the tank has actually
caught - how much came in this month, this year, ever - so a household can
judge for itself whether their own roof and catchment genuinely provide
enough, based on their own record rather than an impression.

The days-remaining figure is a projection from this tank's own recent
record, never a guarantee about how long any real supply will last - the
app gives no engineering or plumbing advice of any kind. It also holds no
money anywhere in it: no tanker prices, no bills, nothing to pay for.

Everything stays on the phone it's used on. There is no account, no
sign-in, and no data of any kind sent anywhere.