Yes, bathing the dog in dish soap does kill the fleas.  However, I have personally

witnessed a flea that appeared to be dead in the bottom of the tub slowly

revive itself.  Whether it would have totally revived I do not know

because I chased it down the drain with very hot water. 

Some say citrus oils help control fleas.  Slice and score the

outside peel, cover with water in a pan and boil it for several minutes to

pull the oils out of the citrus.  Let cool and place liquid into a spray bottle

and apply to your pets coat a couple times a week.

There is also rumors sprinkling garlic powder and brewers yeast over

your pets food will help control fleas.  It is said the flea fines

the taste undesirable.

Your best defense is still your spot on products or flea pills.

If your looking for a minimal chemical way to treat for fleas equal parts of

Baking Soda and Table Salt can be sprinkled over the carpet and over the

pet beds let it set a few hours or over night then vacuum or shake it out.

This will kill the fleas and eggs.  It causes the eggs to dry out and the fleas

to dehydrate.  It is recommended to try a smaller test area on the

carpet first to see how it works for you.

OR

Consult your vet for what products on the market they

feel are safest for your pets.