I'd never make porridge with water at home - but in winter in the office I used to cover a 1/3 bowl of oats with boiling water and then microwave for just 30 seconds.

Once the oirriois cooked (it really should be already) add a teaspoon or two of salted butter to the middle and stir, then sugar to taste.

Suprisingly delicious, quick and repeatable.

I won a few people over who couldn't believe that porridge made with water would be any good, but it was a great winter staple, especially after cycling in, in the cold.