I say 10 to 1

See here; http://www.thegardenersalmanac.co.uk/Data/Comfrey/Comfrey.htm

I have also heard some people say that it should be the same colour as weak tea!

It would depend on how strong the infusion was in the first place, ie how much water to a heap of leaves. Perhaps the weak tea is a better guideline. Better too weak than too strong.

TeeGee I see the site you quote says it is high in potassium. As sulphate of potash is so expensive this year I wondered if the dried leaves would still be useful if kept until next spring as I like to put it on my gooseberries but this year baulked at the price asked.(Sorry to muscle in on your question John)

Not sure about that, why not bottle some undiluted fluid then dilute it when you require it!

I don't see a problem with using last years comfrey tea, added to water. i have had some goo's left over from previous years that I water the veg container with, before and just after planting the veg. I always use the ratio of about 100ml to a 10 litre watering can. Towards the end of the season when I no longer need to make more teas, on the last but one harvest of the comfrey leaves, I mulch my best plants with the fresh leaves under leaf mould. The last lot goes on the compost heap.

Wouldn't have thought of saving the tea. If it doesn't go off I'll give it a try.