Depends on the ester. Obviously those that react are not stable, e.g. TMS esters. But I would say the esters are stable in water at neutral pH at 4°C indefinitely.
That is what I thought, depends on the ester, but I really had no idea. The question is fraught with ambiguity. For those of us in synthesis, stable forever works. For those looking at trace products, I can imagine an ester going away relatively quickly (by comparison). A two phase mixture of ethyl acetate and water will remain two phases forever. A drop of ethyl acetate in a liter of water may disappear relatively quickly.
"I'm more used to working with physiological environments where ester bonds are often an endangered species." This completes the ambiguity. Esters are an endangered species (whatever that means, see above). What are physiological environments? In vivo, in vitro, enzymes, buffers, 37°C, etc?
As pointed out, carbon dioxide will lower the pH. Also, any amount of hydrolysis will increase the acidity and the hydrolysis can become autocatalytic, though with only a weak acid.