Which preposition is correct?

Drinking water is essential for/to/in avoiding dehydration.

Here’s another example, which is the one I’m actually translating:

An online monitoring system is essential for avoiding unscheduled machine downtime.

Ilka

I would write:

Drinking water is essential to avoid dehydration.

Your second sentence is OK as is, but it reads better as:

An online monitoring system is essential to avoid unscheduled machine downtime.

Prepositions seem to be among the trickiest parts of speech. Often, one of two or even three prepositions can be used correctly in the same phrase. At other times, the meaning is ever so slightly altered with a different preposition.

I’ve noticed that when a person acquires even a very strong command of a second language, the nuances of correct preposition use seem to come last if at all. Yet native speakers of a language, whatever their deficiencies in syntax, spelling, etc., almost always use the correct preposition. Not that I want to read a doctoral thesis on the subject . . .

Thanks for your help, Agoraphile.

I’ve noticed the same thing about prepositions. I’ve also noticed that now that I’ve been in Germany for over 10 years, my German starts getting "mixed up" with my English. A preposition that originally sounded wrong in English now might sound right if the same word (and many of them are the same) is used that way in German. (It seems that the synapses in my head are building up new paths!)

It’s very annoying, and I thank Google for giving me the opportunity to take the occasional survey. In this particular instance, however, to/for/in all got a substantial number of hits so I was at a loss. But I prefer your suggestion anyway.

Ilka

[quote author=Agoraphile link=board=grammar;num=1033896083;start=0#1 date=10/06/02 at 08:22:45]I would write:

Drinking water is essential to avoid dehydration.

Your second sentence is OK as is, but it reads better as:

An online monitoring system is essential to avoid unscheduled machine downtime.

Prepositions seem to be among the trickiest parts of speech. Often, one of two or even three prepositions can be used correctly in the same phrase. At other times, the meaning is ever so slightly altered with a different preposition.

I’ve noticed that when a person acquires even a very strong command of a second language, the nuances of correct preposition use seem to come last if at all. Yet native speakers of a language, whatever their deficiencies in syntax, spelling, etc., almost always use the correct preposition. Not that I want to read a doctoral thesis on the subject . . .

Except in this case the "to" is not a prepostion but part of the infinitive "to avoid."  

You could say "essential for avoiding" which uses the present participle (or is that a gerund?) "avoiding."