I would have said the same as zand.
So really all i can suggest is drinking even more water for a few days, just to eliminate it as a possibility.
The various websites i have checked on how-much-water-to-drink seem to suggest 1 litre of water for every 5 stone of bodyweight, not counting coffee (because of its diuretic effects). You may already be drinking more than that, but i have found that i feel significantly better on a day when i exceed that quantity.
Having said that, my understanding is that ketones only become harmful when high blood glucose is present at the same time. Im unsure what level actually constitutes 'high' (maybe a T1 can explain) but a BG of 7-8 definitely isnt!