What are realistic goals for 4-5 hours of training a week?

What goals do you have in mind?

Finishing an oly - likely no problem on that amount of time

Competing - well... not impossible but unlikely.

I did my first season of oly's with one bike, one swim, one run and one bike/run brick per week.  Each session was 45-60 minutes except for the brick which was 90 minutes.  I did pretty well considering it was my first season.  That being said, I did better later when my training volume was closer to 7-8 hours per week.  

Here's how I would split up a 5 hour/week volume:

45 swim

60 min ride/45 min swim

45 min run

75 min ride/30 min run brick

You could do it for sure.  You may not be as fast as you would be with several more hours per week, but if you have pretty moderate goals then 5 hours will get you there for sure.  Or you could be one of those people who can excel and be competitive even with less volume of training than his/her competitors 

I agree, especially if you're already a strong swimmer.

Similar boat as you.   I am ramping up, currently  around ~4 hours a week.   I've been loosely trying to keep 2 swims (45-50 min each) plus 3 runs (30/30/60min, gradually increasing) per week.  Have put the bike mostly on hold for now -- when I start biking again, total time will increase a bit, but unlikely to exceed 5-6 hours a week.

Currently training for 1-2 Olys in 2013 -- not competitive, just aiming to complete and hopefully not DFL.

I asked a similar question here a few months ago. I'd say my PEAK hours per week are maybe 6-7. That maybe happens 2 weeks out of the year, the rest is 2-5 hrs. if I'm lucky.

My longest distance race was an Oly and I did it in 3:05 (thank you, cramps!). Previous year was 3:18. My BEST sprint time was this past July at 1:25.

Well then you should be able to see some improvement in your fitness then.  Make those 4-5 hours count.  If you felt "okay" after your sprints, than an Oly shouldn't be out of the question as far as completion. 

It depends in part on how many years you've been training, age, gender, how efficiently you use those hours, how stressful the rest of your life is, how much time you can commit to recovery, etc.

I've been at this 5 years, and was pretty fit from strength training and other recreational sports before that.  I'm 42 years old.  In the first 6 months of this year, I averaged only 4:15 of total training per week with peak hours in the 6-7 hour range.  Being a coach, I know how to squeeze a lot out of those hours.

In my case, that was enough to finish a very hilly oly in 2:38 and a HIM in 5:40.

Thank you for the responses!  I will definitely get that book!

Last season was my first year biking really other than just for fun.  I also have done some 5ks before and a few 10ks, but never been a serious runner.  So I really think I can build up more this season after what I learned last year.  Last season was after a 3 year break when I had a baby.  I've always been pretty active though.  I did swim D1 in college too, so I am pretty good at knowing how to push myself (although there I days I could use someone throwing a kick board at my head to motivate me )