The answer of course is that the crawl space should be waterproofed as water can find its way into these areas and allow bacteria, mold, and other harmful contaminants to start taking over your home. The question is where you should waterproof on the inside or outside of your home.
The problem here is that if you are not a professional, you may not know the best solution. Many factors come into play when it comes to keeping the crawl space dry. You may have sump pump, but it could be having issues that need resolved such as dirt and debris removed. On the other hand, if you are desire exterior solution, there may be reasons that this solution will not work at all especially if there are items in the way that can stop the excavation process such as driveways or porches.
The truth of the matter is that you should call more than one expert, as you will of course receive conflicting solutions. It would be in your best interest to speak with three different professionals, this way you will have a better idea of exterior or interior waterproofing is for your crawl space.
You should also ask for references and contact the references. Receive a quote and ask how much more the project may increase to in the case of various situations. There are many things and factors involved in waterproofing crawl spaces in your home; however, these areas should not be neglected either or you may have bacteria and even black mold begin to grow in the walls of your home.
All types of bacteria and fungi love damp environment, so give just one of these things the opportunity to enter your home and before you know it your entire crawl space and possibly lower levels of your home as if the basement has the most unwanted guests, mold.
Once you talk with a professional, the expert will be able to provide you with suggestions and what in their own professional opinion will work the best for your solution. The company should be able to provide you with an estimate, as well as experience, licensing, and references.
You do not want to leave the water pool in these areas for long periods of times as the longer the water is there the more problems you can actually get into without even having an idea it could happen. From experience, I know of a home that had a crawl space under the home. The home was not far from a creek and would you believe after the water was left standing for several months, the water became home to snakes. Now, not only do you have problems with mold but also snakes that can enter your home.