Builders sand is course in texture and may have some pebbles in it. Unlike beach sand, the grains are jagged rather than rounded. Sometimes called "sharp sand". Not aware that there would be anything nasty in it. You wouldn't want your house or walkways to be built out of nasty stuff. Play sand is more rounded, is not as permeable, and is thus not preferred for growing mixes. Do read the label and make sure it doesn't have any strange additives, though.

I gather you want to grow veggies in this rather than store veggies in it. A root cellar is for the latter.

No...I want to store veggies, as my post said. I grow organically, and don't want to put my veggies into something where they can become contaminated.

As you said..sidewalks...so no one would care if it came from a toxic waste site...just need to know how to get clean, pure sand.

Ah right. As a storage medium.

You don't care that your sidewalks that your kids play on might have come from a toxic waste site? I would.

I guess sand sounds pretty innocuous, as it's just ground up rock. But the rocks that are ground up can be toxic. Lots of poisonous minerals out there. Probably a mistake to assume that "clean sand" necessarily has to be completely non-toxic. That being said, builders sand is not much more than ground up rock. So if that suits you, then you're good to go.

I should say that beach sand is actually not very healthy. There are loads of biological pathogens in beach sand, and the EPA suggests washing your hands after you go to the beach. I believe that play sand is specifically treated to kill those pathogens, though sitting out in a playscape, it can get contaminated. Most play sand from the playscape is actually pretty filthy, and filled with stuff you wouldn't want your kids to consume.

I have used play sand for storing carrots a few times. It is screened, washed, and sanitized.