The counter itself should have caulk between it and the wall, before the backsplash is installed. The only way to remedy that if it didn't happen is to remove the backsplash. Or, the last row of the backsplash. Then the small gap between the backsplash and counter should be filled with caulk. If the backsplash is tile, then the sanded caulk that matches the grout should be used. So, it sounds as though the right material was ordered and used. How big is the gap between the countertop and backsplash? If the gap is bigger than 1/8", you need some backer to stuff down in there before you caulk over the top to keep the water out. The caulk itself could be old, and have lost it's adhesion. I'd buy a new tube. And make sure that the caulk wasn't applied over grout. The other thing to check is are you sure that the liquid isn't coming from a faucet hole missing a gasket? Or from the rim of the sink itself? Some towels, and some colored water, together with another adult to selectively drip that colored water can help you to see exactly where that water is coming from.

Thanks everyone. You all have good ideas here. I suggested to my husband that we call the manufacturer, but he doesn't want ANYTHING to do with them anymore. He is afraid that they'll send some unqualified person out to do the job, they'll mess up the counter, and our kitchen won't be finished for another 6 weeks while we wait for the new counter to come and be installed... we've done this whole kitchen ourselves and it's taken 10 months because my husband is very anal and very thorough... I think with your suggestions, we can hopefully get this sink out ourselves without damaging the counter. But I might call and try to talk to Whirlpool or Menards anyhow... the easiest thing would be for us to get this out ourselves and return it to Menards... but maybe not the smartest thing. We'll have to think this over. I'm 5 months pregnant and we need to get this kitchen DONE so we can redo the laundry room before baby comes. I will also put tape all over the outside of the enamel so as it continues to pop off, hopefully the tape will prevent it from flying and injuring someone. I didn't consider further breakage of the enamel - that was a good point. And leather gloves for all. I do know one thing for sure: the replacement sink will be Kohler. *sigh* I'll keep you all posted. I appreciate all your insights and tips.

I replaced our vanity top last year with absolutely zero issues either. If the vanity is in rough shape, certainly there’s always a chance it could damage the vanity if removing the top, but i would think it would really have to be in bad shape, or poorly constructed to just fall apart. I agree with others that this guy just wants to either upsell you, or they’re lazy. Either case, keep looking until you find someone that warns you of potential problems and ideally looks at your vanity and can provide specific evidence if he believes it will come apart. Even if it comes apart partially, if you see nothing wrong with it, I dont see why it couldnt be reapired and re-used. If you really like the vanity and see no structural issues, then there’s no reason to buy a new one.

Unintended minor damage occurs during stone installation all the time. That is to be expected when handling large bulky objects in a confined space. There are waivers written into every stone contract that cover incidental damage. Now, if they accidentally drop the stone, that is why they have insurance. It’s for accidents. Incidental damage is not an accident. It is part of the standard risk of the job. Final paint and cabinet touch up always need to happen right at the end of any remodeling job. It is the same for doing any controlled demo in a structure where portions are attempting to be kept. As in if you want a new shower, but want to keep your existing floors. That intersection of old and new on the floor can not be guaranteed not to sustain some damage from the demolition of the shower. That is a risk that the homeowner must assume when trying to blend old and new together without doing a complete gut. Now, if the contractor damages a pipe, and it floods the house, that’s covered by his insurance. The damage to the floor tile that is touching the shower curb will not be covered by anyone. The contractor may offer to install some of the shower tile at the shower entry, but he isn’t going to rip out the entire bath floor and put in new tile. Not without getting paid to do so.